		      A Hacker's Guide to GNUPG
		   ================================
		   (Some notes on GNUPG internals.)


		   ===> Under construction <=======


CVS Access
==========

NOTE: CVS access has been disabled while we are migrating to Subversion.
Watch www.gnupg.org for instarctions on how to use the Subversion repository.

Anonymous read-only CVS access is available:

  cvs -z3 -d :pserver:anoncvs@cvs.gnupg.org:/cvs/gnupg login

use the password "anoncvs".  To check out the the complete
archive use:

  cvs -z3 -d :pserver:anoncvs@cvs.gnupg.org:/cvs/gnupg \
        checkout -R STABLE-BRANCH-1-0 gnupg

This service is provided to help you in hunting bugs and not to deliver
stable snapshots; it may happen that it even does not compile, so please
don't complain. CVS may put a high load on a server, so please don't poll
poll for new updates but wait for an announcement; to receive this you may
want to subscribe to:

    gnupg-commit-watchers@gnupg.org

by sending a mail with subject "subscribe" to

    gnupg-commit-watchers-request@gnupg.org


You must run scripts/autogen.sh before doing the ./configure,
as this creates some needed while which are not in the CVS.
autogen.sh should checks that you have all required tools
installed.


RSYNC access
============
The FTP archive is also available by anonymous rsync.  A daily snapshot
of the CVS head revision is also available.  See rsync(1) and try
"rsync ftp.gnupg.org::" to see available resources.



Special Tools
=============
Documentation is based on the docbook DTD.  Actually we have only the
man page for now.  To build a man page you need the docbook-to-man
tool and all the other thinks needed for SGML processing.  Debian
comes with the docbook tools and you only need this docbook-to-man
script which is comes with gtk-doc or download it from
ftp.openit.de:/pub/devel/sgml.	If you don't have it everything
should still work fine but you will have only a dummy man page.


RFCs
====

1423  Privacy Enhancement for Internet Electronic Mail:
      Part III: Algorithms, Modes, and Identifiers.

1489  Registration of a Cyrillic Character Set.

1750  Randomness Recommendations for Security.

1991  PGP Message Exchange Formats.

2015  MIME Security with Pretty Good Privacy (PGP).

2144  The CAST-128 Encryption Algorithm.

2279  UTF-8, a transformation format of ISO 10646.

2440  OpenPGP.



Debug Flags
-----------
Use the option "--debug n" to output debug information. This option
can be used multiple times, all values are ORed; n maybe prefixed with
0x to use hex-values.

     value  used for
     -----  ----------------------------------------------
      1     packet reading/writing
      2     MPI details
      4     ciphers and primes (may reveal sensitive data)
      8     iobuf filter functions
      16    iobuf stuff
      32    memory allocation stuff
      64    caching
      128   show memory statistics at exit
      256   trust verification stuff




Directory Layout
----------------
  ./		Readme, configure
  ./scripts	Scripts needed by configure and others
  ./doc 	Documentation
  ./util	General purpose utility function
  ./mpi 	Multi precision integer library
  ./cipher	Cryptographic functions
  ./g10 	GnuPG application
  ./tools	Some helper and demo programs
  ./keybox	The keybox library (under construction)
  ./gcrypt	Stuff needed to build libgcrypt (under construction)


Detailed Roadmap
----------------
g10/g10.c	Main module with option parsing and all the stuff you have
		to do on startup.  Also has the exout handler and some
		helper functions.
g10/sign.c      Create signature and optionally encrypt

g10/parse-packet.c
g10/build-packet.c
g10/free-packet.c
		Parsing and creating of OpenPGP message packets.

g10/getkey.c    Key selection code
g10/pkclist.c   Build a list of public keys
g10/skclist.c   Build a list of secret keys
g10/ringedit.c  Keyring I/O
g10/keydb.h

g10/keyid.c	Helper functions to get the keyid, fingerprint etc.


g10/trustdb.c    
g10/trustdb.h
g10/tdbdump.c
               Management of the trustdb.gpg

g10/compress.c Filter to handle compression
g10/filter.h   Declarations for all filter functions
g10/delkey.c   Delete a key
g10/kbnode.c   Helper for the KBNODE linked list
g10/main.h     Prototypes and some constants
g10/mainproc.c Message processing
g10/armor.c    Ascii armor filter 
g10/mdfilter.c Filter to calculate hashs
g10/textfilter.c Filter to handle CR/LF and trailing white space
g10/cipher.c   En-/Decryption filter
g10/misc.c     Utlity functions
g10/options.h  Structure with all the command line options
               and related constants
g10/openfile.c Create/Open Files
g10/tdbio.c    I/O handling for the trustdb.gpg
g10/tdbio.h
g10/hkp.h      Keyserver access
g10/hkp.c
g10/packet.h   Defintion of OpenPGP structures.
g10/passphrase.c  Passphrase handling code
g10/pubkey-enc.c  
g10/seckey-cert.c
g10/seskey.c
g10/import.c
g10/export.c
g10/comment.c
g10/status.c
g10/status.h
g10/sign.c
g10/plaintext.c
g10/encr-data.c
g10/encode.c
g10/revoke.c
g10/keylist.c
g10/sig-check.c
g10/signal.c
g10/helptext.c
g10/verify.c
g10/decrypt.c
g10/keyedit.c
g10/dearmor.c
g10/keygen.c



Memory allocation
-----------------
Use only the functions:

    m_alloc()
    m_alloc_clear()
    m_strdup()
    m_free()

If you want to store a passphrase or some other sensitive data you may
want to use m_alloc_secure() instead of m_alloc(), as this puts the data
into a memory region which is protected from swapping (on some platforms).
m_free() works for both.  This functions will not return if there is not
enough memory available.



Logging
-------






Option parsing
---------------
GNUPG does not use getopt or GNU getopt but functions of it's own.  See
util/argparse.c for details.  The advantage of these functions is that
it is more easy to display and maintain the help texts for the options.
The same option table is also used to parse resource files.



What is an IOBUF
----------------
This is the data structure used for most I/O of gnupg.	It is similar
to System V Streams but much simpler.  Because OpenPGP messages are nested
in different ways; the use of such a system has big advantages.  Here is
an example, how it works:  If the parser sees a packet header with a partial
length, it pushes the block_filter onto the IOBUF to handle these partial
length packets: from now on you don't have to worry about this.  When it sees
a compressed packet it pushes the uncompress filter and the next read byte
is one which has already been uncompressed by this filter. Same goes for
enciphered packet, plaintext packets and so on.  The file g10/encode.c
might be a good staring point to see how it is used  - actually this is
the other way: constructing messages using pushed filters but it may be
easier to understand.


How to use the message digest functions
---------------------------------------
cipher/md.c implements an interface to hash (message digest functions).

a) If you have a common part of data and some variable parts
   and you need to hash of the concatenated parts, you can use this:
	md = md_open(...)
	md_write( md,  common_part )
	md1 = md_copy( md )
	md_write(md1, part1)
	md_final(md1);
	digest1 = md_read(md1)
	md2 = md_copy( md )
	md_write(md2, part2)
	md_final(md2);
	digest2 = md_read(md2)

   An example are key signatures; the key packet is the common part
   and the user-id packets are the variable parts.

b) If you need a running digest you should use this:
	md = md_open(...)
	md_write( md, part1 )
	digest_of_part1 = md_digest( md );
	md_write( md, part2 )
	digest_of_part1_cat_part2 = md_digest( md );
	....

Both methods may be combined. [Please see the source for the real syntax]




How to use the cipher functions
-------------------------------
cipher/cipher.c implements the interface to symmetric encryption functions.
As usual you have a function to open a cipher (which returns a handle to be used
with all other functions), some functions to set the key and other stuff and
a encrypt and decrypt function which does the real work.  You probably know
how to work with files - so it should really be easy to work with these
functions.  Here is an example:

    CIPHER_HANDLE hd;

    hd = cipher_open( CIPHER_ALGO_TWOFISH, CIPHER_MODE_CFB, 0 );
    if( !hd )
	oops( use other function to check for the real error );
    rc = cipher_setkey( hd, key256bit, 32 ) )
    if( rc )
	oops( weak key or something like this );
    cipher_setiv( hd, some_IV_or_NULL_for_all_zeroes );
    cipher_encrypt( hd, plain, cipher, size );
    cipher_close( hd );



How to use the public key functions
-----------------------------------
cipher/pubkey.c implements the interface to asymmetric encryption and
signature functions. This is basically the same as with the symmetric
counterparts, but due to their nature it is a little bit more complicated.

   [Give an example]


                                                              -*- text -*-

NOTE: The definitive reference is the file from the SVN trunk.

Format of colon listings
========================
First an example:

$ gpg --fixed-list-mode --with-colons --list-keys \
   --with-fingerprint --with-fingerprint wk@gnupg.org

pub:f:1024:17:6C7EE1B8621CC013:899817715:1055898235::m:::scESC:
fpr:::::::::ECAF7590EB3443B5C7CF3ACB6C7EE1B8621CC013:
uid:f::::::::Werner Koch <wk@g10code.com>:
uid:f::::::::Werner Koch <wk@gnupg.org>:
sub:f:1536:16:06AD222CADF6A6E1:919537416:1036177416:::::e:
fpr:::::::::CF8BCC4B18DE08FCD8A1615906AD222CADF6A6E1:
sub:r:1536:20:5CE086B5B5A18FF4:899817788:1025961788:::::esc:
fpr:::::::::AB059359A3B81F410FCFF97F5CE086B5B5A18FF4:

The double --with-fingerprint prints the fingerprint for the subkeys
too, --fixed-list-mode is themodern listing way printing dates in
seconds since Epoch and does not merge the first userID with the pub
record.


 1. Field:  Type of record
	    pub = public key
            crt = X.509 certificate
            crs = X.509 certificate and private key available
	    sub = subkey (secondary key)
	    sec = secret key
	    ssb = secret subkey (secondary key)
	    uid = user id (only field 10 is used).
	    uat = user attribute (same as user id except for field 10).
            sig = signature
            rev = revocation signature
	    fpr = fingerprint: (fingerprint is in field 10)
	    pkd = public key data (special field format, see below)
            grp = reserved for gpgsm
            rvk = revocation key
            tru = trust database information
            spk = signature subpacket

 2. Field:  A letter describing the calculated trust. This is a single
	    letter, but be prepared that additional information may follow
	    in some future versions. (not used for secret keys)
		o = Unknown (this key is new to the system)
                i = The key is invalid (e.g. due to a missing self-signature)
		d = The key has been disabled
		    (deprecated - use the 'D' in field 12 instead)
		r = The key has been revoked
		e = The key has expired
		- = Unknown trust (i.e. no value assigned)
		q = Undefined trust
	            '-' and 'q' may safely be treated as the same
		    value for most purposes
		n = Don't trust this key at all
		m = There is marginal trust in this key
		f = The key is fully trusted
		u = The key is ultimately trusted.  This often means
		    that the secret key is available, but any key may
		    be marked as ultimately trusted.
 3. Field:  length of key in bits.
 4. Field:  Algorithm:	1 = RSA
		       16 = Elgamal (encrypt only)
		       17 = DSA (sometimes called DH, sign only)
		       20 = Elgamal (sign and encrypt - don't use them!)
	    (for other id's see include/cipher.h)
 5. Field:  KeyID
 6. Field:  Creation Date (in UTC).  For UID and UAT records, this is the
            self-signature date.  Note that the dae is usally printed
            in seconds since epoch, however, we are migrating to an ISO
            8601 format (e.g. "19660205T091500").  This is currently
            only relevant for X.509, A simple way to detect the format
            is be scannning for the 'T'.
 7. Field:  Key or user ID/user attribute expiration date or empty if none.
 8. Field:  Used for serial number in crt records (used to be the Local-ID).
            For UID and UAT records, this is a hash of the user ID contents
            used to represent that exact user ID.  For trust signatures,
            this is the trust depth seperated by the trust value by a
            space.
 9. Field:  Ownertrust (primary public keys only)
	    This is a single letter, but be prepared that additional
	    information may follow in some future versions.  For trust
	    signatures with a regular expression, this is the regular
	    expression value, quoted as in field 10.
10. Field:  User-ID.  The value is quoted like a C string to avoid
	    control characters (the colon is quoted "\x3a").
            This is not used with --fixed-list-mode in gpg.
            A UAT record puts the attribute subpacket count here, a
	    space, and then the total attribute subpacket size.
            In gpgsm the issuer name comes here
            An FPR record stores the fingerprint here.
            The fingerprint of an revocation key is stored here.
11. Field:  Signature class.  This is a 2 digit hexnumber followed by
            either the letter 'x' for an exportable signature or the
            letter 'l' for a local-only signature.
            The class byte of an revocation key is also given here,
            'x' and 'l' ist used the same way.
12. Field:  Key capabilities:
                e = encrypt
                s = sign
                c = certify
                a = authentication
	    A key may have any combination of them in any order.  In
	    addition to these letters, the primary key has uppercase
	    versions of the letters to denote the _usable_
	    capabilities of the entire key, and a potential letter 'D'
	    to indicate a disabled key.
13. Field:  Used in FPR records for S/MIME keys to store the fingerprint of
            the issuer certificate.  This is useful to build the
            certificate path based on certificates stored in the local
            keyDB; it is only filled if the issue certificate is
            available. The advantage of using this value is that it is
            guaranteed to have been been build by the same lookup
            algorithm as gpgsm uses.
            For "uid" recods this lists the preferences n the sameway the 
            -edit menu does.
	    For "sig" records, this is the fingerprint of the key that
	    issued the signature.  Note that this is only filled in if
	    the signature verified correctly.  Note also that for
	    various technical reasons, this fingerprint is only
	    available if --no-sig-cache is used.

14. Field   Flag field used in the --edit menu output:

15. Field   Used in sec/sbb to print the serial number of a token
            (internal protect mode 1002) or a '#' if that key is a
            simple stub (internal protect mode 1001)

All dates are displayed in the format yyyy-mm-dd unless you use the
option --fixed-list-mode in which case they are displayed as seconds
since Epoch.  More fields may be added later, so parsers should be
prepared for this. When parsing a number the parser should stop at the
first non-number character so that additional information can later be
added.

If field 1 has the tag "pkd", a listing looks like this:
pkd:0:1024:B665B1435F4C2 .... FF26ABB:
    !  !   !-- the value
    !  !------ for information number of bits in the value
    !--------- index (eg. DSA goes from 0 to 3: p,q,g,y)


The "tru" trust database records have the fields:

 2: Reason for staleness of trust.  If this field is empty, then the
    trustdb is not stale.  This field may have multiple flags in it:

    o: Trustdb is old
    t: Trustdb was built with a different trust model than the one we
       are using now.

 3: Trust model:
    0: Classic trust model, as used in PGP 2.x.
    1: PGP trust model, as used in PGP 6 and later.  This is the same
       as the classic trust model, except for the addition of trust
       signatures.

    GnuPG before version 1.4 used the classic trust model by default.
    GnuPG 1.4 and later uses the PGP trust model by default.

 4: Date trustdb was created in seconds since 1/1/1970.
 5: Date trustdb will expire in seconds since 1/1/1970.

The "spk" signature subpacket records have the fields:

 2: Subpacket number as per RFC-2440 and later.
 3: Flags in hex.  Currently the only two bits assigned are 1, to
    indicate that the subpacket came from the hashed part of the
    signature, and 2, to indicate the subpacket was marked critical.
 4: Length of the subpacket.  Note that this is the length of the
    subpacket, and not the length of field 5 below.  Due to the need
    for %-encoding, the length of field 5 may be up to 3x this value.
 5: The subpacket data.  Printable ASCII is shown as ASCII, but other
    values are rendered as %XX where XX is the hex value for the byte.


Format of the "--status-fd" output
==================================
Every line is prefixed with "[GNUPG:] ", followed by a keyword with
the type of the status line and a some arguments depending on the
type (maybe none); an application should always be prepared to see
more arguments in future versions.


    NEWSIG
        May be issued right before a signature verification starts.  This
        is useful to define a context for parsing ERROR status
        messages.  No arguments are currently defined.

    GOODSIG	<long keyid>  <username>
	The signature with the keyid is good.  For each signature only
        one of the three codes GOODSIG, BADSIG or ERRSIG will be
        emitted and they may be used as a marker for a new signature.
        The username is the primary one encoded in UTF-8 and %XX
        escaped.

    EXPSIG	<long keyid>  <username>
	The signature with the keyid is good, but the signature is
	expired. The username is the primary one encoded in UTF-8 and
	%XX escaped.

    EXPKEYSIG	<long keyid>  <username>
	The signature with the keyid is good, but the signature was
	made by an expired key. The username is the primary one
	encoded in UTF-8 and %XX escaped.

    REVKEYSIG	<long keyid>  <username>
	The signature with the keyid is good, but the signature was
	made by a revoked key. The username is the primary one
	encoded in UTF-8 and %XX escaped.

    BADSIG	<long keyid>  <username>
	The signature with the keyid has not been verified okay.
        The username is the primary one encoded in UTF-8 and %XX
        escaped.

    ERRSIG  <long keyid>  <pubkey_algo> <hash_algo> \
	    <sig_class> <timestamp> <rc>
	It was not possible to check the signature.  This may be
	caused by a missing public key or an unsupported algorithm.
	A RC of 4 indicates unknown algorithm, a 9 indicates a missing
	public key. The other fields give more information about
	this signature.  sig_class is a 2 byte hex-value.

        Note, that TIMESTAMP may either be a number with seconds since
        epoch or an ISO 8601 string which can be detected by the
        presence of the letter 'T' inside.

    VALIDSIG	<fingerprint in hex> <sig_creation_date> <sig-timestamp>
		<expire-timestamp> <sig-version> <reserved> <pubkey-algo>
		<hash-algo> <sig-class> <primary-key-fpr>

	The signature with the keyid is good. This is the same as
	GOODSIG but has the fingerprint as the argument. Both status
	lines are emitted for a good signature.  All arguments here
	are on one long line.  sig-timestamp is the signature creation
	time in seconds after the epoch. expire-timestamp is the
	signature expiration time in seconds after the epoch (zero
	means "does not expire"). sig-version, pubkey-algo, hash-algo,
	and sig-class (a 2-byte hex value) are all straight from the
	signature packet.  PRIMARY-KEY-FPR is the fingerprint of the
	primary key or identical to the first argument.  This is
	useful to get back to the primary key without running gpg
	again for this purpose.

        Note, that *-TIMESTAMP may either be a number with seconds
        since epoch or an ISO 8601 string which can be detected by the
        presence of the letter 'T' inside.

    SIG_ID  <radix64_string>  <sig_creation_date>  <sig-timestamp>
	This is emitted only for signatures of class 0 or 1 which
	have been verified okay.  The string is a signature id
	and may be used in applications to detect replay attacks
	of signed messages.  Note that only DLP algorithms give
	unique ids - others may yield duplicated ones when they
	have been created in the same second.

        Note, that SIG-TIMESTAMP may either be a number with seconds
        since epoch or an ISO 8601 string which can be detected by the
        presence of the letter 'T' inside.


    ENC_TO  <long keyid>  <keytype>  <keylength>
	The message is encrypted to this keyid.
	keytype is the numerical value of the public key algorithm,
	keylength is the length of the key or 0 if it is not known
	(which is currently always the case).

    NODATA  <what>
	No data has been found. Codes for what are:
	    1 - No armored data.
	    2 - Expected a packet but did not found one.
	    3 - Invalid packet found, this may indicate a non OpenPGP
                message.
            4 - signature expected but not found
	You may see more than one of these status lines.

    UNEXPECTED <what>
        Unexpected data has been encountered
            0 - not further specified               1       
  

    TRUST_UNDEFINED <error token>
    TRUST_NEVER  <error token>
    TRUST_MARGINAL
    TRUST_FULLY
    TRUST_ULTIMATE
	For good signatures one of these status lines are emitted
	to indicate how trustworthy the signature is.  The error token
        values are currently only emiited by gpgsm.

    PKA_TRUST_GOOD <mailbox>
    PKA_TRUST_BAD  <mailbox>
        Depending on the outcome of the PKA check one of the above
        status codes is emitted in addition to a TRUST_* status.
        Without PKA info available or 

    SIGEXPIRED
	This is deprecated in favor of KEYEXPIRED.

    KEYEXPIRED <expire-timestamp>
	The key has expired.  expire-timestamp is the expiration time
	in seconds after the epoch.

        Note, that TIMESTAMP may either be a number with seconds since
        epoch or an ISO 8601 string which can be detected by the
        presence of the letter 'T' inside.

    KEYREVOKED
	The used key has been revoked by its owner.  No arguments yet.

    BADARMOR
	The ASCII armor is corrupted.  No arguments yet.

    RSA_OR_IDEA
	The IDEA algorithms has been used in the data.  A
	program might want to fallback to another program to handle
	the data if GnuPG failed.  This status message used to be emitted
        also for RSA but this has been dropped after the RSA patent expired.
        However we can't change the name of the message.

    SHM_INFO
    SHM_GET
    SHM_GET_BOOL
    SHM_GET_HIDDEN

    GET_BOOL
    GET_LINE
    GET_HIDDEN
    GOT_IT

    NEED_PASSPHRASE <long main keyid> <long keyid> <keytype> <keylength>
	Issued whenever a passphrase is needed.
	keytype is the numerical value of the public key algorithm
	or 0 if this is not applicable, keylength is the length
	of the key or 0 if it is not known (this is currently always the case).

    NEED_PASSPHRASE_SYM <cipher_algo> <s2k_mode> <s2k_hash>
	Issued whenever a passphrase for symmetric encryption is needed.

    NEED_PASSPHRASE_PIN <card_type> <chvno> [<serialno>]
        Issued whenever a PIN is requested to unlock a card.

    MISSING_PASSPHRASE
	No passphrase was supplied.  An application which encounters this
	message may want to stop parsing immediately because the next message
	will probably be a BAD_PASSPHRASE.  However, if the application
	is a wrapper around the key edit menu functionality it might not
	make sense to stop parsing but simply ignoring the following
	BAD_PASSPHRASE.

    BAD_PASSPHRASE <long keyid>
	The supplied passphrase was wrong or not given.  In the latter case
	you may have seen a MISSING_PASSPHRASE.

    GOOD_PASSPHRASE
	The supplied passphrase was good and the secret key material
	is therefore usable.

    DECRYPTION_FAILED
	The symmetric decryption failed - one reason could be a wrong
	passphrase for a symmetrical encrypted message.

    DECRYPTION_OKAY
	The decryption process succeeded.  This means, that either the
	correct secret key has been used or the correct passphrase
	for a conventional encrypted message was given.  The program
	itself may return an errorcode because it may not be possible to
	verify a signature for some reasons.

    NO_PUBKEY  <long keyid>
    NO_SECKEY  <long keyid>
	The key is not available

    IMPORT_CHECK <long keyid> <fingerprint> <user ID>
        This status is emitted in interactive mode right before
        the "import.okay" prompt.

    IMPORTED   <long keyid>  <username>
	The keyid and name of the signature just imported

    IMPORT_OK  <reason> [<fingerprint>]
        The key with the primary key's FINGERPRINT has been imported.
        Reason flags:
          0 := Not actually changed
          1 := Entirely new key.
          2 := New user IDs
          4 := New signatures
          8 := New subkeys 
         16 := Contains private key.
        The flags may be ORed.

    IMPORT_PROBLEM <reason> [<fingerprint>]
        Issued for each import failure.  Reason codes are:
          0 := "No specific reason given".
          1 := "Invalid Certificate".
          2 := "Issuer Certificate missing".
          3 := "Certificate Chain too long".
          4 := "Error storing certificate".

    IMPORT_RES <count> <no_user_id> <imported> <imported_rsa> <unchanged>
	<n_uids> <n_subk> <n_sigs> <n_revoc> <sec_read> <sec_imported> <sec_dups> <not_imported>
	Final statistics on import process (this is one long line)

    FILE_START <what> <filename>
	Start processing a file <filename>.  <what> indicates the performed
	operation:
	    1 - verify
            2 - encrypt
            3 - decrypt        

    FILE_DONE
	Marks the end of a file processing which has been started
	by FILE_START.

    BEGIN_DECRYPTION
    END_DECRYPTION
	Mark the start and end of the actual decryption process.  These
	are also emitted when in --list-only mode.

    BEGIN_ENCRYPTION  <mdc_method> <sym_algo>
    END_ENCRYPTION
	Mark the start and end of the actual encryption process.

    BEGIN_SIGNING
       Mark the start of the actual signing process. This may be used
       as an indication that all requested secret keys are ready for
       use.

    DELETE_PROBLEM reason_code
	Deleting a key failed.	Reason codes are:
	    1 - No such key
	    2 - Must delete secret key first
            3 - Ambigious specification

    PROGRESS what char cur total
	Used by the primegen and Public key functions to indicate progress.
	"char" is the character displayed with no --status-fd enabled, with
	the linefeed replaced by an 'X'.  "cur" is the current amount
	done and "total" is amount to be done; a "total" of 0 indicates that
	the total amount is not known.	100/100 may be used to detect the
	end of operation.
        Well known values for WHAT:
             "pk_dsa"   - DSA key generation
             "pk_elg"   - Elgamal key generation
             "primegen" - Prime generation
             "need_entropy" - Waiting for new entropy in the RNG
             "file:XXX" - processing file XXX
                          (note that current gpg versions leave out the
                           "file:" prefix).
             "tick"     - generic tick without any special meaning - useful
                          for letting clients know that the server is
                          still working.
             "starting_agent" - A gpg-agent was started because it is not
                          running as a daemon.

        
    SIG_CREATED <type> <pubkey algo> <hash algo> <class> <timestamp> <key fpr>
	A signature has been created using these parameters.
	    type:  'D' = detached
		   'C' = cleartext
		   'S' = standard
		   (only the first character should be checked)
	    class: 2 hex digits with the signature class

        Note, that TIMESTAMP may either be a number with seconds since
        epoch or an ISO 8601 string which can be detected by the
        presence of the letter 'T' inside.
        
    KEY_CREATED <type> <fingerprint> [<handle>]
        A key has been created
            type: 'B' = primary and subkey
                  'P' = primary
                  'S' = subkey
        The fingerprint is one of the primary key for type B and P and
        the one of the subkey for S.  Handle is an arbitrary
        non-whitespace string used to match key parameters from batch
        key creation run.

    KEY_NOT_CREATED [<handle>]
        The key from batch run has not been created due to errors.


    SESSION_KEY  <algo>:<hexdigits>
	The session key used to decrypt the message.  This message will
	only be emitted when the special option --show-session-key
	is used.  The format is suitable to be passed to the option
	--override-session-key

    NOTATION_NAME <name> 
    NOTATION_DATA <string>
        name and string are %XX escaped; the data may be splitted
        among several notation_data lines.

    USERID_HINT <long main keyid> <string>
        Give a hint about the user ID for a certain keyID. 

    POLICY_URL <string>
        string is %XX escaped

    BEGIN_STREAM
    END_STREAM
        Issued by pipemode.

    INV_RECP <reason> <requested_recipient>
        Issued for each unusable recipient. The reasons codes
        currently in use are:
          0 := "No specific reason given".
          1 := "Not Found"
          2 := "Ambigious specification"
          3 := "Wrong key usage"
          4 := "Key revoked"
          5 := "Key expired"
          6 := "No CRL known"
          7 := "CRL too old"
          8 := "Policy mismatch"
          9 := "Not a secret key"
	 10 := "Key not trusted"

        Note that this status is also used for gpgsm's SIGNER command
        where it relates to signer's of course.

    NO_RECP <reserved>
        Issued when no recipients are usable.

    ALREADY_SIGNED <long-keyid>
        Warning: This is experimental and might be removed at any time.

    TRUNCATED <maxno>
        The output was truncated to MAXNO items.  This status code is issued
        for certain external requests

    ERROR <error location> <error code> 

        This is a generic error status message, it might be followed
        by error location specific data. <error token> and
        <error_location> should not contain a space.  The error code
        is a either a string commencing with a letter or such string
        prefix with a numerical error code and an underscore; e.g.:
        "151011327_EOF"

    ATTRIBUTE <fpr> <octets> <type> <index> <count>
	      <timestamp> <expiredate> <flags>
	This is one long line issued for each attribute subpacket when
	an attribute packet is seen during key listing.  <fpr> is the
	fingerprint of the key. <octets> is the length of the
	attribute subpacket. <type> is the attribute type
	(1==image). <index>/<count> indicates that this is the Nth
	indexed subpacket of count total subpackets in this attribute
	packet.  <timestamp> and <expiredate> are from the
	self-signature on the attribute packet.  If the attribute
	packet does not have a valid self-signature, then the
	timestamp is 0.  <flags> are a bitwise OR of:
		0x01 = this attribute packet is a primary uid
		0x02 = this attribute packet is revoked
		0x04 = this attribute packet is expired

    CARDCTRL <what> [<serialno>]
        This is used to control smartcard operations.
        Defined values for WHAT are:
           1 = Request insertion of a card.  Serialnumber may be given
               to request a specific card.
           2 = Request removal of a card.
           3 = Card with serialnumber detected
           4 = No card available.
           5 = No card reader available


    PLAINTEXT <format> <timestamp> <filename>
        This indicates the format of the plaintext that is about to be
        written.  The format is a 1 byte hex code that shows the
        format of the plaintext: 62 ('b') is binary data, 74 ('t') is
        text data with no character set specified, and 75 ('u') is
        text data encoded in the UTF-8 character set.  The timestamp
        is in seconds since the epoch.  If a filename is available it
        gets printed as the third argument, percent-escaped as usual.

    PLAINTEXT_LENGTH <length>
        This indicates the length of the plaintext that is about to be
        written.  Note that if the plaintext packet has partial length
        encoding it is not possible to know the length ahead of time.
        In that case, this status tag does not appear.

    SIG_SUBPACKET <type> <flags> <len> <data>
        This indicates that a signature subpacket was seen.  The
        format is the same as the "spk" record above.

    SC_OP_FAILURE [<code>]
        An operation on a smartcard definitely failed.  Currently
        there is no indication of the actual error code, but
        application should be prepared to later accept more arguments.
        Defined values for CODE are:
           0 - unspecified error (identically to a missing CODE)
           1 - canceled
           2 - bad PIN

    SC_OP_SUCCESS
        A smart card operaion succeeded.  This status is only printed
        for certain operation and is mostly useful to check whether a
        PIN change really worked.

    BACKUP_KEY_CREATED fingerprint fname
        A backup key named FNAME has been created for the key with
        KEYID.


Format of the "--attribute-fd" output
=====================================

When --attribute-fd is set, during key listings (--list-keys,
--list-secret-keys) GnuPG dumps each attribute packet to the file
descriptor specified.  --attribute-fd is intended for use with
--status-fd as part of the required information is carried on the
ATTRIBUTE status tag (see above).

The contents of the attribute data is specified by 2440bis, but for
convenience, here is the Photo ID format, as it is currently the only
attribute defined:

   Byte 0-1:  The length of the image header.  Due to a historical
              accident (i.e. oops!) back in the NAI PGP days, this is
              a little-endian number.  Currently 16 (0x10 0x00).

   Byte 2:    The image header version.  Currently 0x01.

   Byte 3:    Encoding format.  0x01 == JPEG.

   Byte 4-15: Reserved, and currently unused.

   All other data after this header is raw image (JPEG) data.


Format of the "--list-config" output
====================================

--list-config outputs information about the GnuPG configuration for
the benefit of frontends or other programs that call GnuPG.  There are
several list-config items, all colon delimited like the rest of the
--with-colons output.  The first field is always "cfg" to indicate
configuration information.  The second field is one of (with
examples):

version: the third field contains the version of GnuPG.

   cfg:version:1.3.5

pubkey: the third field contains the public key algorithmdcaiphers
	this version of GnuPG supports, separated by semicolons.  The
	algorithm numbers are as specified in RFC-2440.

   cfg:pubkey:1;2;3;16;17

cipher: the third field contains the symmetric ciphers this version of
	GnuPG supports, separated by semicolons.  The cipher numbers
	are as specified in RFC-2440.

   cfg:cipher:2;3;4;7;8;9;10

digest: the third field contains the digest (hash) algorithms this
	version of GnuPG supports, separated by semicolons.  The
	digest numbers are as specified in RFC-2440.

   cfg:digest:1;2;3;8;9;10

compress: the third field contains the compression algorithms this
	  version of GnuPG supports, separated by semicolons.  The
	  algorithm numbers are as specified in RFC-2440.

   cfg:compress:0;1;2;3

group: the third field contains the name of the group, and the fourth
       field contains the values that the group expands to, separated
       by semicolons.

For example, a group of:
   group mynames = paige 0x12345678 joe patti

would result in:
   cfg:group:mynames:patti;joe;0x12345678;paige


Key generation
==============
    Key generation shows progress by printing different characters to
    stderr:
	     "."  Last 10 Miller-Rabin tests failed
	     "+"  Miller-Rabin test succeeded
	     "!"  Reloading the pool with fresh prime numbers
	     "^"  Checking a new value for the generator
	     "<"  Size of one factor decreased
	     ">"  Size of one factor increased

    The prime number for Elgamal is generated this way:

    1) Make a prime number q of 160, 200, 240 bits (depending on the keysize)
    2) Select the length of the other prime factors to be at least the size
       of q and calculate the number of prime factors needed
    3) Make a pool of prime numbers, each of the length determined in step 2
    4) Get a new permutation out of the pool or continue with step 3
       if we have tested all permutations.
    5) Calculate a candidate prime p = 2 * q * p[1] * ... * p[n] + 1
    6) Check that this prime has the correct length (this may change q if
       it seems not to be possible to make a prime of the desired length)
    7) Check whether this is a prime using trial divisions and the
       Miller-Rabin test.
    8) Continue with step 4 if we did not find a prime in step 7.
    9) Find a generator for that prime.

    This algorithm is based on Lim and Lee's suggestion from the
    Crypto '97 proceedings p. 260.


Unattended key generation
=========================
This feature allows unattended generation of keys controlled by a
parameter file.  To use this feature, you use --gen-key together with
--batch and feed the parameters either from stdin or from a file given
on the commandline.

The format of this file is as follows:
  o Text only, line length is limited to about 1000 chars.
  o You must use UTF-8 encoding to specify non-ascii characters.
  o Empty lines are ignored.
  o Leading and trailing spaces are ignored.
  o A hash sign as the first non white space character indicates a comment line.
  o Control statements are indicated by a leading percent sign, the
    arguments are separated by white space from the keyword.
  o Parameters are specified by a keyword, followed by a colon.  Arguments
    are separated by white space.
  o The first parameter must be "Key-Type", control statements
    may be placed anywhere.
  o Key generation takes place when either the end of the parameter file
    is reached, the next "Key-Type" parameter is encountered or at the
    control statement "%commit"
  o Control statements:
    %echo <text>
	Print <text>.
    %dry-run
	Suppress actual key generation (useful for syntax checking).
    %commit
	Perform the key generation.  An implicit commit is done
	at the next "Key-Type" parameter.
    %pubring <filename>
    %secring <filename>
	Do not write the key to the default or commandline given
	keyring but to <filename>.  This must be given before the first
	commit to take place, duplicate specification of the same filename
	is ignored, the last filename before a commit is used.
	The filename is used until a new filename is used (at commit points)
	and all keys are written to that file.	If a new filename is given,
	this file is created (and overwrites an existing one).
	Both control statements must be given.
   o The order of the parameters does not matter except for "Key-Type"
     which must be the first parameter.  The parameters are only for the
     generated keyblock and parameters from previous key generations are not
     used. Some syntactically checks may be performed.
     The currently defined parameters are:
     Key-Type: <algo-number>|<algo-string>
	Starts a new parameter block by giving the type of the
	primary key. The algorithm must be capable of signing.
	This is a required parameter.
     Key-Length: <length-in-bits>
	Length of the key in bits.  Default is 1024.
     Key-Usage: <usage-list>
        Space or comma delimited list of key usage, allowed values are
        "encrypt", "sign", and "auth".  This is used to generate the
        key flags.  Please make sure that the algorithm is capable of
        this usage.  Note that OpenPGP requires that all primary keys
        are capable of certification, so no matter what usage is given
        here, the "cert" flag will be on.  If no Key-Usage is
        specified, all the allowed usages for that particular
        algorithm are used.
     Subkey-Type: <algo-number>|<algo-string>
	This generates a secondary key.  Currently only one subkey
	can be handled.
     Subkey-Length: <length-in-bits>
	Length of the subkey in bits.  Default is 1024.
     Subkey-Usage: <usage-list>
        Similar to Key-Usage.
     Passphrase: <string>
	If you want to specify a passphrase for the secret key,
	enter it here.	Default is not to use any passphrase.
     Name-Real: <string>
     Name-Comment: <string>
     Name-Email: <string>
	The 3 parts of a key. Remember to use UTF-8 here.
	If you don't give any of them, no user ID is created.
     Expire-Date: <iso-date>|(<number>[d|w|m|y])
	Set the expiration date for the key (and the subkey).  It
	may either be entered in ISO date format (2000-08-15) or as
	number of days, weeks, month or years. Without a letter days
	are assumed.
     Preferences: <string>
        Set the cipher, hash, and compression preference values for
	this key.  This expects the same type of string as "setpref"
	in the --edit menu.
     Revoker: <algo>:<fpr> [sensitive]
        Add a designated revoker to the generated key.  Algo is the
	public key algorithm of the designated revoker (i.e. RSA=1,
	DSA=17, etc.)  Fpr is the fingerprint of the designated
	revoker.  The optional "sensitive" flag marks the designated
	revoker as sensitive information.  Only v4 keys may be
	designated revokers.
     Handle: <string>
        This is an optional parameter only used with the status lines
        KEY_CREATED and KEY_NOT_CREATED.  STRING may be up to 100
        characters and should not contain spaces.  It is useful for
        batch key generation to associate a key parameter block with a
        status line.
     Keyserver: <string>
        This is an optional parameter that specifies the preferred
        keyserver URL for the key.


Here is an example:
$ cat >foo <<EOF
     %echo Generating a standard key
     Key-Type: DSA
     Key-Length: 1024
     Subkey-Type: ELG-E
     Subkey-Length: 1024
     Name-Real: Joe Tester
     Name-Comment: with stupid passphrase
     Name-Email: joe@foo.bar
     Expire-Date: 0
     Passphrase: abc
     %pubring foo.pub
     %secring foo.sec
     # Do a commit here, so that we can later print "done" :-)
     %commit
     %echo done
EOF
$ gpg --batch --gen-key foo
 [...]
$ gpg --no-default-keyring --secret-keyring ./foo.sec \
				  --keyring ./foo.pub --list-secret-keys
/home/wk/work/gnupg-stable/scratch/foo.sec
------------------------------------------
sec  1024D/915A878D 2000-03-09 Joe Tester (with stupid passphrase) <joe@foo.bar>
ssb  1024g/8F70E2C0 2000-03-09



Layout of the TrustDB
=====================
The TrustDB is built from fixed length records, where the first byte
describes the record type.  All numeric values are stored in network
byte order. The length of each record is 40 bytes. The first record of
the DB is always of type 1 and this is the only record of this type.

FIXME:  The layout changed, document it here.

  Record type 0:
  --------------
    Unused record, can be reused for any purpose.

  Record type 1:
  --------------
    Version information for this TrustDB.  This is always the first
    record of the DB and the only one with type 1.
     1 byte value 1
     3 bytes 'gpg'  magic value
     1 byte Version of the TrustDB (2)
     1 byte marginals needed
     1 byte completes needed
     1 byte max_cert_depth
	    The three items are used to check whether the cached
	    validity value from the dir record can be used.
     1 u32  locked flags [not used]
     1 u32  timestamp of trustdb creation
     1 u32  timestamp of last modification which may affect the validity
	    of keys in the trustdb.  This value is checked against the
	    validity timestamp in the dir records.
     1 u32  timestamp of last validation [currently not used]
	    (Used to keep track of the time, when this TrustDB was checked
	     against the pubring)
     1 u32  record number of keyhashtable [currently not used]
     1 u32  first free record
     1 u32  record number of shadow directory hash table [currently not used]
	    It does not make sense to combine this table with the key table
	    because the keyid is not in every case a part of the fingerprint.
     1 u32  record number of the trusthashtbale


  Record type 2: (directory record)
  --------------
    Informations about a public key certificate.
    These are static values which are never changed without user interaction.

     1 byte value 2
     1 byte  reserved
     1 u32   LID     .	(This is simply the record number of this record.)
     1 u32   List of key-records (the first one is the primary key)
     1 u32   List of uid-records
     1 u32   cache record
     1 byte  ownertrust
     1 byte  dirflag
     1 byte  maximum validity of all the user ids
     1 u32   time of last validity check.
     1 u32   Must check when this time has been reached.
	     (0 = no check required)


  Record type 3:  (key record)
  --------------
    Informations about a primary public key.
    (This is mainly used to lookup a trust record)

     1 byte value 3
     1 byte  reserved
     1 u32   LID
     1 u32   next   - next key record
     7 bytes reserved
     1 byte  keyflags
     1 byte  pubkey algorithm
     1 byte  length of the fingerprint (in bytes)
     20 bytes fingerprint of the public key
	      (This is the value we use to identify a key)

  Record type 4: (uid record)
  --------------
    Informations about a userid
    We do not store the userid but the hash value of the userid because that
    is sufficient.

     1 byte value 4
     1 byte reserved
     1 u32  LID  points to the directory record.
     1 u32  next   next userid
     1 u32  pointer to preference record
     1 u32  siglist  list of valid signatures
     1 byte uidflags
     1 byte validity of the key calculated over this user id
     20 bytes ripemd160 hash of the username.


  Record type 5: (pref record)
  --------------
    This record type is not anymore used.

     1 byte value 5
     1 byte   reserved
     1 u32  LID; points to the directory record (and not to the uid record!).
	    (or 0 for standard preference record)
     1 u32  next
     30 byte preference data

  Record type 6  (sigrec)
  -------------
    Used to keep track of key signatures. Self-signatures are not
    stored.  If a public key is not in the DB, the signature points to
    a shadow dir record, which in turn has a list of records which
    might be interested in this key (and the signature record here
    is one).

     1 byte   value 6
     1 byte   reserved
     1 u32    LID	    points back to the dir record
     1 u32    next   next sigrec of this uid or 0 to indicate the
		     last sigrec.
     6 times
	1 u32  Local_id of signatures dir or shadow dir record
	1 byte Flag: Bit 0 = checked: Bit 1 is valid (we have a real
			     directory record for this)
			 1 = valid is set (but may be revoked)



  Record type 8: (shadow directory record)
  --------------
    This record is used to reserve a LID for a public key.  We
    need this to create the sig records of other keys, even if we
    do not yet have the public key of the signature.
    This record (the record number to be more precise) will be reused
    as the dir record when we import the real public key.

     1 byte value 8
     1 byte  reserved
     1 u32   LID      (This is simply the record number of this record.)
     2 u32   keyid
     1 byte  pubkey algorithm
     3 byte reserved
     1 u32   hintlist	A list of records which have references to
			this key.  This is used for fast access to
			signature records which are not yet checked.
			Note, that this is only a hint and the actual records
			may not anymore hold signature records for that key
			but that the code cares about this.
    18 byte reserved



  Record Type 10 (hash table)
  --------------
    Due to the fact that we use fingerprints to lookup keys, we can
    implement quick access by some simple hash methods, and avoid
    the overhead of gdbm.  A property of fingerprints is that they can be
    used directly as hash values.  (They can be considered as strong
    random numbers.)
      What we use is a dynamic multilevel architecture, which combines
    hashtables, record lists, and linked lists.

    This record is a hashtable of 256 entries; a special property
    is that all these records are stored consecutively to make one
    big table. The hash value is simple the 1st, 2nd, ... byte of
    the fingerprint (depending on the indirection level).

    When used to hash shadow directory records, a different table is used
    and indexed by the keyid.

     1 byte value 10
     1 byte reserved
     n u32  recnum; n depends on the record length:
	    n = (reclen-2)/4  which yields 9 for the current record length
	    of 40 bytes.

    the total number of such record which makes up the table is:
	 m = (256+n-1) / n
    which is 29 for a record length of 40.

    To look up a key we use the first byte of the fingerprint to get
    the recnum from this hashtable and look up the addressed record:
       - If this record is another hashtable, we use 2nd byte
	 to index this hash table and so on.
       - if this record is a hashlist, we walk all entries
	 until we found one a matching one.
       - if this record is a key record, we compare the
	 fingerprint and to decide whether it is the requested key;


  Record type 11 (hash list)
  --------------
    see hash table for an explanation.
    This is also used for other purposes.

    1 byte value 11
    1 byte reserved
    1 u32  next 	 next hash list record
    n times		 n = (reclen-5)/5
	1 u32  recnum

    For the current record length of 40, n is 7



  Record type 254 (free record)
  ---------------
    All these records form a linked list of unused records.
     1 byte  value 254
     1 byte  reserved (0)
     1 u32   next_free



Packet Headers
===============

GNUPG uses PGP 2 packet headers and also understands OpenPGP packet header.
There is one enhancement used with the old style packet headers:

   CTB bits 10, the "packet-length length bits", have values listed in
   the following table:

      00 - 1-byte packet-length field
      01 - 2-byte packet-length field
      10 - 4-byte packet-length field
      11 - no packet length supplied, unknown packet length

   As indicated in this table, depending on the packet-length length
   bits, the remaining 1, 2, 4, or 0 bytes of the packet structure field
   are a "packet-length field".  The packet-length field is a whole
   number field.  The value of the packet-length field is defined to be
   the value of the whole number field.

   A value of 11 is currently used in one place: on compressed data.
   That is, a compressed data block currently looks like <A3 01 . .  .>,
   where <A3>, binary 10 1000 11, is an indefinite-length packet. The
   proper interpretation is "until the end of the enclosing structure",
   although it should never appear outermost (where the enclosing
   structure is a file).

+  This will be changed with another version, where the new meaning of
+  the value 11 (see below) will also take place.
+
+  A value of 11 for other packets enables a special length encoding,
+  which is used in case, where the length of the following packet can
+  not be determined prior to writing the packet; especially this will
+  be used if large amounts of data are processed in filter mode.
+
+  It works like this: After the CTB (with a length field of 11) a
+  marker field is used, which gives the length of the following datablock.
+  This is a simple 2 byte field (MSB first) containing the amount of data
+  following this field, not including this length field. After this datablock
+  another length field follows, which gives the size of the next datablock.
+  A value of 0 indicates the end of the packet. The maximum size of a
+  data block is limited to 65534, thereby reserving a value of 0xffff for
+  future extensions. These length markers must be inserted into the data
+  stream just before writing the data out.
+
+  This 2 byte field is large enough, because the application must buffer
+  this amount of data to prepend the length marker before writing it out.
+  Data block sizes larger than about 32k doesn't make any sense. Note
+  that this may also be used for compressed data streams, but we must use
+  another packet version to tell the application that it can not assume,
+  that this is the last packet.


GNU extensions to the S2K algorithm
===================================
S2K mode 101 is used to identify these extensions.
After the hash algorithm the 3 bytes "GNU" are used to make
clear that these are extensions for GNU, the next bytes gives the
GNU protection mode - 1000.  Defined modes are:
  1001 - do not store the secret part at all
  1002 - a stub to access smartcards (not used in 1.2.x)


Pipemode
========
NOTE:  This is deprecated and will be removed in future versions.

This mode can be used to perform multiple operations with one call to
gpg. It comes handy in cases where you have to verify a lot of
signatures. Currently we support only detached signatures.  This mode
is a kludge to avoid running gpg n daemon mode and using Unix Domain
Sockets to pass the data to it.  There is no easy portable way to do
this under Windows, so we use plain old pipes which do work well under
Windows.  Because there is no way to signal multiple EOFs in a pipe we
have to embed control commands in the data stream: We distinguish
between a data state and a control state.  Initially the system is in
data state but it won't accept any data.  Instead it waits for
transition to control state which is done by sending a single '@'
character.  While in control state the control command os expected and
this command is just a single byte after which the system falls back
to data state (but does not necesary accept data now).  The simplest
control command is a '@' which just inserts this character into the
data stream.

Here is the format we use for detached signatures:
"@<"  - Begin of new stream
"@B"  - Detached signature follows.
        This emits a control packet (1,'B')
<detached_signature>
"@t"  - Signed text follows. 
        This emits the control packet (2, 'B')
<signed_text>
"@."  - End of operation. The final control packet forces signature
        verification
"@>"  - End of stream   






Other Notes
===========
    * For packet version 3 we calculate the keyids this way:
	RSA	:= low 64 bits of n
	ELGAMAL := build a v3 pubkey packet (with CTB 0x99) and calculate
		   a rmd160 hash value from it. This is used as the
		   fingerprint and the low 64 bits are the keyid.

    * Revocation certificates consist only of the signature packet;
      "import" knows how to handle this.  The rationale behind it is
      to keep them small.







Keyserver Message Format
=========================

The keyserver may be contacted by a Unix Domain socket or via TCP.

The format of a request is:

====
command-tag
"Content-length:" digits
CRLF
=======

Where command-tag is

NOOP
GET <user-name>
PUT
DELETE <user-name>


The format of a response is:

======
"GNUPG/1.0" status-code status-text
"Content-length:" digits
CRLF
============
followed by <digits> bytes of data


Status codes are:

     o	1xx: Informational - Request received, continuing process

     o	2xx: Success - The action was successfully received, understood,
	and accepted

     o	4xx: Client Error - The request contains bad syntax or cannot be
	fulfilled

     o	5xx: Server Error - The server failed to fulfill an apparently
	valid request



Documentation on HKP (the http keyserver protocol):

A minimalistic HTTP server on port 11371 recognizes a GET for /pks/lookup.
The standard http URL encoded query parameters are this (always key=value):

- op=index (like pgp -kv), op=vindex (like pgp -kvv) and op=get (like
  pgp -kxa)

- search=<stringlist>. This is a list of words that must occur in the key.
  The words are delimited with space, points, @ and so on. The delimiters
  are not searched for and the order of the words doesn't matter (but see
  next option).

- exact=on. This switch tells the hkp server to only report exact matching
  keys back. In this case the order and the "delimiters" are important.

- fingerprint=on. Also reports the fingerprints when used with 'index' or
  'vindex'

The keyserver also recognizes http-POSTs to /pks/add. Use this to upload
keys.


A better way to do this would be a request like:

   /pks/lookup/<gnupg_formatierte_user_id>?op=<operation>

This can be implemented using Hurd's translator mechanism.
However, I think the whole key server stuff has to be re-thought;
I have some ideas and probably create a white paper.


GnuPG Frequently Asked Questions


Version: 1.6.3
Last-Modified: Jul 30, 2003
Maintained-by: David D. Scribner, <faq 'at' gnupg.org>


This is the GnuPG FAQ. The latest HTML version is available
here. <http://www.gnupg.org/documentation/faqs.html>

The index is generated automatically, so there may be errors. Not all
questions may be in the section they belong to. Suggestions about how
to improve the structure of this FAQ are welcome.

Please send additions and corrections to the maintainer. It would be
most convenient if you could provide the answer to be included here
as well. Your help is very much appreciated!

Please, don't send message like "This should be a FAQ - what's the
answer?". If it hasn't been asked before, it isn't a FAQ. In that case
you could search in the mailing list archive.


 1. GENERAL
   1.1) What is GnuPG?
   1.2) Is GnuPG compatible with PGP?
   1.3) Is GnuPG free to use for personal or commercial use?
   1.4) What conventions are used in this FAQ?

 2. SOURCES of INFORMATION
   2.1) Where can I find more information on GnuPG?
   2.2) Where do I get GnuPG?

 3. INSTALLATION 
   3.1) Which OSes does GnuPG run on?
   3.2) Which random data gatherer should I use?
   3.3) How do I include support for RSA and IDEA?

 4. USAGE
   4.1) What is the recommended key size?
   4.2) Why does it sometimes take so long to create keys?
   4.3) And it really takes long when I work on a remote system. Why?
   4.4) What is the difference between options and commands?
   4.5) I can't delete a user ID on my secret keyring because it has
	already been deleted on my public keyring. What can I do?
   4.6) I can't delete my secret key because the public key disappeared.
	What can I do?
   4.7) What are trust, validity and ownertrust?
   4.8) How do I sign a patch file?
   4.9) Where is the "encrypt-to-self" option?
   4.10) How can I get rid of the Version and Comment headers in armored
	messages?
   4.11) What does the "You are using the xxxx character set." mean?
   4.12) How can I get list of key IDs used to encrypt a message?
   4.13) Why can't I decrypt files encrypted as symmetrical-only (-c) with
	a version of GnuPG prior to 1.0.1.
   4.14) How can I use GnuPG in an automated environment?
   4.15) Which email-client can I use with GnuPG?
   4.16) Can't we have a gpg library?
   4.17) I have successfully generated a revocation certificate, but I don't
	understand how to send it to the key servers.
   4.18) How do I put my keyring in a different directory?
   4.19) How do I verify signed packages?
   4.20) How do I export a keyring with only selected signatures (keys)?
   4.21) I still have my secret key, but lost my public key. What can I do?
   4.22) Clearsigned messages sent from my web-mail account have an invalid
	signature. Why?

 5. COMPATIBILITY ISSUES
   5.1) How can I encrypt a message with GnuPG so that PGP is able to decrypt it?
   5.2) How do I migrate from PGP 2.x to GnuPG?
   5.3) (removed)
   5.4) Why is PGP 5.x not able to encrypt messages with some keys?
   5.5) Why is PGP 5.x not able to verify my messages?
   5.6) How do I transfer owner trust values from PGP to GnuPG?
   5.7) PGP does not like my secret key.
   5.8) GnuPG no longer installs a ~/.gnupg/options file. Is it missing?
   5.9) How do you export GnuPG keys for use with PGP?

 6. PROBLEMS and ERROR MESSAGES
   6.1) Why do I get "gpg: Warning: using insecure memory!"
   6.2) Large File Support doesn't work ...
   6.3) In the edit menu the trust values are not displayed correctly after
	signing uids. Why?
   6.4) What does "skipping pubkey 1: already loaded" mean?
   6.5) GnuPG 1.0.4 doesn't create ~/.gnupg ...
   6.6) An Elgamal signature does not verify anymore since version 1.0.2 ...
   6.7) Old versions of GnuPG can't verify Elgamal signatures
   6.8) When I use --clearsign, the plain text has sometimes extra dashes
	in it - why?
   6.9) What is the thing with "can't handle multiple signatures"?
   6.10) If I submit a key to a keyserver, nothing happens ...
   6.11) I get "gpg: waiting for lock ..."
   6.12) Older gpg binaries (e.g., 1.0) have problems with keys from newer
	gpg binaries ...
   6.13) With 1.0.4, I get "this cipher algorithm is deprecated ..."
   6.14) Some dates are displayed as ????-??-??. Why?
   6.15) I still have a problem. How do I report a bug?
   6.16) Why doesn't GnuPG support X.509 certificates?
   6.17) Why do national characters in my user ID look funny?
   6.18) I get 'sed' errors when running ./configure on Mac OS X ...
   6.19) Why does GnuPG 1.0.6 bail out on keyrings used with 1.0.7?
   6.20) I upgraded to GnuPG version 1.0.7 and now it takes longer to load my
	keyrings. What can I do?
   6.21) Doesn't a fully trusted user ID on a key prevent warning messages
	when encrypting to other IDs on the key?
   6.22) I just compiled GnuPG from source on my GNU/Linux RPM-based system
	and it's not working. Why?

 7. ADVANCED TOPICS
   7.1) How does this whole thing work?
   7.2) Why are some signatures with an ELG-E key valid?
   7.3) How does the whole trust thing work?
   7.4) What kind of output is this: "key C26EE891.298, uid 09FB: ...."?
   7.5) How do I interpret some of the informational outputs?
   7.6) Are the header lines of a cleartext signature part of the signed
	material?
   7.7) What is the list of preferred algorithms?
   7.8) How do I change the list of preferred algorithms?

 8. ACKNOWLEDGEMENTS


1. GENERAL

1.1) What is GnuPG?

    GnuPG stands for GNU Privacy Guard and <http://www.gnupg.org>
    is GNU's tool for secure communication and data storage. It can be
    used to encrypt data and to create digital signatures. It includes
    an advanced key management facility and is compliant with the
    proposed OpenPGP Internet standard as described in RFC 2440.
	    <http://www.rfc-editor.org/>
    As such, it is aimed to be compatible with PGP from PGP Corp. and
    other OpenPGP tools

1.2) Is GnuPG compatible with PGP?

    In general, yes. GnuPG and newer PGP releases should be implementing
    the OpenPGP standard. But there are some interoperability problems.
    See question 5.1 for details.

1.3) Is GnuPG free to use for personal or commercial use?

    Yes. GnuPG is part of the GNU family of tools and applications built
    and provided in accordance with the Free Software Foundation (FSF)
    General Public License (GPL). Therefore the software is free to copy,
    use, modify and distribute in accordance with that license. Please
    read the file titled COPYING that accompanies the application for
    more information.

1.4) What conventions are used in this FAQ?

    Although GnuPG is being developed for several operating systems
    (often in parallel), the conventions used in this FAQ reflect a
    UNIX shell environment. For Win32 users, references to a shell
    prompt (`$') should be interpreted as a command prompt (`>'),
    directory names separated by a forward slash (`/') may need to be
    converted to a back slash (`\'), and a tilde (`~') represents a
    user's "home" directory (reference question 4.18 for an example).

    Some command-lines presented in this FAQ are too long to properly
    display in some browsers for the web page version of this file, and
    have been split into two or more lines. For these commands please
    remember to enter the entire command-string on one line or the
    command will error, or at minimum not give the desired results. 

    Please keep in mind that this FAQ contains information that may not
    apply to your particular version, as new features and bug fixes are
    added on a continuing basis (reference the NEWS file included with
    the source or package for noteworthy changes between versions). One
    item to note is that starting with GnuPG version 1.1.92 the file
    containing user options and settings has been renamed from "options"
    to "gpg.conf". Information in the FAQ that relates to the options
    file may be interchangable with the newer gpg.conf file in many
    instances. See question 5.8 for details.


2. SOURCES of INFORMATION

2.1) Where can I find more information on GnuPG?

    On-line resources:

    The documentation page is located at <http://www.gnupg.org/documentation/>.
    Also, have a look at the HOWTOs and the GNU Privacy Handbook (GPH,
    available in English, Spanish and Russian). The latter provides a
    detailed user's guide to GnuPG. You'll also find a document about how
    to convert from PGP 2.x to GnuPG.

    At <http://www.gnupg.org/documentation/mailing-lists.html> you'll find
    an online archive of the GnuPG mailing lists. Most interesting should
    be gnupg-users for all user-related issues and gnupg-devel if you want
    to get in touch with the developers.

    In addition, searchable archives can be found on MARC, e.g.: 
    gnupg-users: <http://marc.theaimsgroup.com/?l=gnupg-users&r=1&w=2>
    gnupg-devel: <http://marc.theaimsgroup.com/?l=gnupg-devel&r=1&w=2>

    PLEASE:
    Before posting to a list, read this FAQ and the available documentation.
    In addition, search the list archive - maybe your question has already
    been discussed. This way you help people focus on topics that have not
    yet been resolved.

    The GnuPG source distribution contains a subdirectory:

       ./doc

    where some additional documentation is located (mainly interesting
    for hackers, not the casual user).

2.2) Where do I get GnuPG?

    You can download the GNU Privacy Guard from its primary FTP server
    <ftp://ftp.gnupg.org/gcrypt/> or from one of the mirrors:

       <http://www.gnupg.org/download/mirrors.html>

    The current stable version is 1.2.2. Please upgrade to this version as
    it includes additional features, functions and security fixes that may
    not have existed in prior versions.


3. INSTALLATION 

3.1) Which OSes does GnuPG run on?

    It should run on most Unices as well as Windows versions (including
    Windows NT/2000) and Macintosh OS/X. A list of OSes reported to be OK
    is presented at:

       <http://www.gnupg.org/download/supported_systems.html>

3.2) Which random data gatherer should I use?

    "Good" random numbers are crucial for the security of your encryption.
    Different operating systems provide a variety of more or less quality
    random data. Linux and *BSD provide kernel generated random data
    through /dev/random - this should be the preferred choice on these
    systems. Also Solaris users with the SUNWski package installed have
    a /dev/random. In these cases, use the configure option:

       --enable-static-rnd=linux

    In addition, there's also the kernel random device by Andi Maier
    <http://www.cosy.sbg.ac.at/~andi/SUNrand/>, but it's still beta. Use at your
    own risk!

    On other systems, the Entropy Gathering Daemon (EGD) is a good choice.
    It is a perl-daemon that monitors system activity and hashes it into
    random data. See the download page <http://www.gnupg.org/download/>
    to obtain EGD. Use:

       --enable-static-rnd=egd

    here.

    If the above options do not work, you can use the random number
    generator "unix". This is *very* slow and should be avoided. The
    random quality isn't very good so don't use it on sensitive data.

3.3) How do I include support for RSA and IDEA?

    RSA is included as of GnuPG version 1.0.3.

    The official GnuPG distribution does not contain IDEA due to a patent
    restriction. The patent does not expire before 2007 so don't expect
    official support before then.

    However, there is an unofficial module to include it even in earlier
    versions of GnuPG. It's available from
    <ftp://ftp.gnupg.dk/pub/contrib-dk/>. Look for:

       idea.c.gz        (c module)
       idea.c.gz.sig    (signature file)

       ideadll.zip      (c module and win32 dll)
       ideadll.zip.sig  (signature file)

    Compilation directives are in the headers of these files. You will
    then need to add the following line to your ~/.gnupg/gpg.conf or
    ~/.gnupg/options file:

       load-extension idea


4. USAGE

4.1) What is the recommended key size?

    1024 bit for DSA signatures; even for plain Elgamal signatures.
    This is sufficient as the size of the hash is probably the weakest
    link if the key size is larger than 1024 bits. Encryption keys may
    have greater sizes, but you should then check the fingerprint of
    this key:

       $ gpg --fingerprint <user ID>

    As for the key algorithms, you should stick with the default (i.e.,
    DSA signature and Elgamal encryption). An Elgamal signing key has
    the following disadvantages: the signature is larger, it is hard
    to create such a key useful for signatures which can withstand some
    real world attacks, you don't get any extra security compared to
    DSA, and there might be compatibility problems with certain PGP
    versions. It has only been introduced because at the time it was
    not clear whether there was a patent on DSA.

4.2) Why does it sometimes take so long to create keys?

    The problem here is that we need a lot of random bytes and for that
    we (on Linux the /dev/random device) must collect some random data.
    It is really not easy to fill the Linux internal entropy buffer; I
    talked to Ted Ts'o and he commented that the best way to fill the
    buffer is to play with your keyboard. Good security has its price.
    What I do is to hit several times on the shift, control, alternate,
    and caps lock keys, because these keys do not produce output to the
    screen. This way you get your keys really fast (it's the same thing
    PGP2 does).

    Another problem might be another program which eats up your random
    bytes (a program (look at your daemons) that reads from /dev/random).

4.3) And it really takes long when I work on a remote system. Why?

    Don't do this at all! You should never create keys or even use GnuPG
    on a remote system because you normally have no physical control
    over your secret key ring (which is in most cases vulnerable to
    advanced dictionary attacks) - I strongly encourage everyone to only
    create keys on a local computer (a disconnected laptop is probably
    the best choice) and if you need it on your connected box (I know,
    we all do this) be sure to have a strong password for both your
    account and for your secret key, and that you can trust your system
    administrator.

    When I check GnuPG on a remote system via ssh (I have no Alpha here)
    ;-) I have the same problem. It takes a *very* long time to create
    the keys, so I use a special option, --quick-random, to generate
    insecure keys which are only good for some tests.

4.4) What is the difference between options and commands?

    If you do a 'gpg --help', you will get two separate lists. The first
    is a list of commands. The second is a list of options. Whenever you
    run GPG, you must pick exactly one command (with one exception,
    see below). You may pick one or more options. The command should,
    just by convention, come at the end of the argument list, after all
    the options. If the command takes a file (all the basic ones do),
    the filename comes at the very end. So the basic way to run gpg is:

       $ gpg [--option something] [--option2] [--option3 something] --command file

    Some options take arguments. For example, the --output option (which
    can be abbreviated as -o) is an option that takes a filename. The
    option's argument must follow immediately after the option itself,
    otherwise gpg doesn't know which option the argument is supposed to
    paired with. As an option, --output and its filename must come before
    the command. The --recipient (-r) option takes a name or keyID to
    encrypt the message to, which must come right after the -r option.
    The --encrypt (or -e) command comes after all the options and is
    followed by the file you wish to encrypt. Therefore in this example
    the command-line issued would be:

       $ gpg -r alice -o secret.txt -e test.txt

    If you write the options out in full, it is easier to read:

       $ gpg --recipient alice --output secret.txt --encrypt test.txt

    If you're encrypting to a file with the extension ".txt", then you'd
    probably expect to see ASCII-armored text in the file (not binary),
    so you need to add the --armor (-a) option, which doesn't take any
    arguments:

       $ gpg --armor --recipient alice --output secret.txt --encrypt test.txt

    If you imagine square brackets around the optional parts, it becomes
    a bit clearer:

       $ gpg [--armor] [--recipient alice] [--output secret.txt] --encrypt test.txt

    The optional parts can be rearranged any way you want:

       $ gpg --output secret.txt --recipient alice --armor --encrypt test.txt

    If your filename begins with a hyphen (e.g. "-a.txt"), GnuPG assumes
    this is an option and may complain. To avoid this you have to either
    use "./-a.txt", or stop the option and command processing with two
    hyphens: "-- -a.txt".

    *The exception to using only one command:* signing and encrypting
    at the same time. For this you can combine both commands, such as in:

       $ gpg [--options] --sign --encrypt foo.txt

4.5) I can't delete a user ID on my secret keyring because it has
    already been deleted on my public keyring. What can I do?

    Because you can only select from the public key ring, there is no
    direct way to do this. However it is not very complicated to do
    anyway. Create a new user ID with exactly the same name and you
    will see that there are now two identical user IDs on the secret
    ring. Now select this user ID and delete it. Both user IDs will be
    removed from the secret ring.

4.6) I can't delete my secret key because the public key disappeared.
    What can I do?

    To select a key a search is always done on the public keyring,
    therefore it is not possible to select a secret key without
    having the public key. Normally it should never happen that the
    public key got lost but the secret key is still available. The
    reality is different, so GnuPG implements a special way to deal
    with it: Simply use the long keyID to specify the key to delete,
    which can be obtained by using the --with-colons options (it is
    the fifth field in the lines beginning with "sec").

    If you've lost your public key and need to recreate it instead
    for continued use with your secret key, you may be able to use
    gpgsplit as detailed in question 4.21.

4.7) What are trust, validity and ownertrust?

    With GnuPG, the term "ownertrust" is used instead of "trust" to
    help clarify that this is the value you have assigned to a key
    to express how much you trust the owner of this key to correctly
    sign (and thereby introduce) other keys. The "validity", or
    calculated trust, is a value which indicates how much GnuPG
    considers a key as being valid (that it really belongs to the
    one who claims to be the owner of the key). For more information
    on trust values see the chapter "The Web of Trust" in The GNU
    Privacy Handbook.

4.8) How do I sign a patch file?

    Use "gpg --clearsign --not-dash-escaped ...". The problem with
    --clearsign is that all lines starting with a dash are quoted with
    "- "; obviously diff produces many lines starting with a dash and
    these are then quoted and that is not good for a patch ;-). To use
    a patch file without removing the cleartext signature, the special
    option --not-dash-escaped may be used to suppress generation of
    these escape sequences. You should not mail such a patch because
    spaces and line endings are also subject to the signature and a
    mailer may not preserve these. If you want to mail a file you can
    simply sign it using your MUA (Mail User Agent).

4.9) Where is the "encrypt-to-self" option?

    Use "--encrypt-to your_keyID". You can use more than one of these
    options. To temporarily override the use of this additional key,
    you can use the option "--no-encrypt-to".

4.10) How can I get rid of the Version and Comment headers in armored
    messages?

    Use "--no-version --comment ''". Note that the left over blank line
    is required by the protocol.

4.11) What does the "You are using the xxxx character set." mean?

    This note is printed when UTF-8 mapping has to be done. Make sure
    that the displayed character set is the one you have activated on
    your system. Since "iso-8859-1" is the character set most used,
    this is the default. You can change the charset with the option
    "--charset". It is important that your active character set matches
    the one displayed - if not, restrict yourself to plain 7 bit ASCII
    and no mapping has to be done.

4.12) How can I get list of key IDs used to encrypt a message?

       $ gpg --batch --decrypt --list-only --status-fd 1 2>/dev/null |
         awk '/^\[GNUPG:\] ENC_TO / { print $3 }'

4.13) Why can't I decrypt files encrypted as symmetrical-only (-c) with
    a version of GnuPG prior to 1.0.1.

    There was a bug in GnuPG versions prior to 1.0.1 which affected files
    only if 3DES or Twofish was used for symmetric-only encryption (this has
    never been the default). The bug has been fixed, but to enable decryption
    of old files you should run gpg with the option "--emulate-3des-s2k-bug",
    decrypt the file and encrypt it again without this option.

    NOTE: This option was removed in GnuPG development version 1.1.0 and later
    updates, so you will need to use a version between 1.0.1 and 1.0.7 to
    re-encrypt any affected files.

4.14) How can I use GnuPG in an automated environment?

    You should use the option --batch and don't use passphrases as
    there is usually no way to store it more securely than on the
    secret keyring itself. The suggested way to create keys for an
    automated environment is:

    On a secure machine:
     If you want to do automatic signing, create a signing subkey
           for your key (use the interactive key editing menu by issueing
           the command 'gpg --edit-key keyID', enter "addkey" and select
           the DSA key type).
     Make sure that you use a passphrase (needed by the current
           implementation).
     gpg --export-secret-subkeys --no-comment foo >secring.auto
     Copy secring.auto and the public keyring to a test directory.
     Change to this directory.
     gpg --homedir . --edit foo and use "passwd" to remove the
           passphrase from the subkeys. You may also want to remove all
           unused subkeys.
     Copy secring.auto to a floppy and carry it to the target box.

    On the target machine:
     Install secring.auto as the secret keyring.
     Now you can start your new service. It's also a good idea to
           install an intrusion detection system so that you hopefully
           get a notice of an successful intrusion, so that you in turn
           can revoke all the subkeys installed on that machine and
           install new subkeys.

4.15) Which email-client can I use with GnuPG?

    Using GnuPG to encrypt email is one of the most popular uses.
    Several mail clients or mail user agents (MUAs) support GnuPG to
    varying degrees. Simplifying a bit, there are two ways mail can be
    encrypted with GnuPG: the "old style" ASCII armor (i.e. cleartext
    encryption), and RFC 2015 style (previously PGP/MIME, now OpenPGP).
    The latter has full MIME support. Some MUAs support only one of
    them, so whichever you actually use depends on your needs as well
    as the capabilities of your addressee. As well, support may be
    native to the MUA, or provided via "plug-ins" or external tools.

    The following list is not exhaustive:

       MUA            OpenPGP ASCII   How? (N,P,T)
       -------------------------------------------------------------
       Calypso           N      Y      P (Unixmail)
       Elm               N      Y      T (mailpgp,morepgp)
       Elm ME+           N      Y      N
       Emacs/Gnus        Y      Y      T (Mailcrypt,gpg.el)
       Emacs/Mew         Y      Y      N
       Emacs/VM          N      Y      T (Mailcrypt)
       Evolution         Y      Y      N
       Exmh              Y      Y      N
       GNUMail.app       Y      Y      P (PGPBundle)
       GPGMail           Y      Y      N
       KMail (<=1.4.x)   N      Y      N
       KMail (1.5.x)     Y(P)   Y(N)   P/N
       Mozilla           Y      Y      P (Enigmail)
       Mulberry          Y      Y      P
       Mutt              Y      Y      N
       Sylpheed          Y      Y      N
       Sylpheed-claws    Y      Y      N
       TkRat             Y      Y      N
       XEmacs/Gnus       Y      Y      T (Mailcrypt)
       XEmacs/Mew        Y      Y      N
       XEmacs/VM         N      Y      T (Mailcrypt)
       XFmail            Y      Y      N

       N - Native, P - Plug-in, T - External Tool

    The following table lists proprietary MUAs. The GNU Project
    suggests against the use of these programs, but they are listed
    for interoperability reasons for your convenience.

       MUA            OpenPGP ASCII   How? (N,P,T)
       -------------------------------------------------------------
       Apple Mail        Y      Y      P (GPGMail)
       Becky2            Y      Y      P (BkGnuPG)
       Eudora            Y      Y      P (EuroraGPG)
       Eudora Pro        Y      Y      P (EudoraGPG)
       Lotus Notes       N      Y      P
       Netscape 4.x      N      Y      P
       Netscape 7.x      Y      Y      P (Enigmail)
       Novell Groupwise  N      Y      P
       Outlook           N      Y      P (G-Data)
       Outlook Express   N      Y      P (GPGOE)
       Pegasus           N      Y      P (QDPGP,PM-PGP)
       Pine              N      Y      T (pgpenvelope,(gpg|pgp)4pine)
       Postme            N      Y      P (GPGPPL)
       The Bat!          N      Y      P (Ritlabs)

    Good overviews of OpenPGP-support can be found at:
    <http://www.openpgp.fr.st/courrier_en.html> and
    <http://www.bretschneidernet.de/tips/secmua.html>.

    Users of Win32 MUAs that lack OpenPGP support may look into
    using GPGrelay <http://gpgrelay.sourceforge.net>, a small
    email-relaying server that uses GnuPG to enable many email clients
    to send and receive emails that conform to PGP-MIME (RFC 2015).

4.16) Can't we have a gpg library?

    This has been frequently requested. However, the current viewpoint
    of the GnuPG maintainers is that this would lead to several security
    issues and will therefore not be implemented in the foreseeable
    future. However, for some areas of application gpgme could do the
    trick. You'll find it at <ftp://ftp.gnupg.org/gcrypt/alpha/gpgme>.

4.17) I have successfully generated a revocation certificate, but I don't
    understand how to send it to the key servers.

    Most keyservers don't accept a 'bare' revocation certificate. You
    have to import the certificate into gpg first:

       $ gpg --import my-revocation.asc

    then send the revoked key to the keyservers:

       $ gpg --keyserver certserver.pgp.com --send-keys mykeyid

    (or use a keyserver web interface for this).

4.18) How do I put my keyring in a different directory?

    GnuPG keeps several files in a special homedir directory. These
    include the options file, pubring.gpg, secring.gpg, trustdb.gpg,
    and others. GnuPG will always create and use these files. On unices,
    the homedir is usually ~/.gnupg; on Windows "C:\gnupg\".

    If you want to put your keyrings somewhere else, use the option:

       --homedir /my/path/

    to make GnuPG create all its files in that directory. Your keyring
    will be "/my/path/pubring.gpg". This way you can store your secrets
    on a floppy disk. Don't use "--keyring" as its purpose is to specify
    additional keyring files.

4.19) How do I verify signed packages?

    Before you can verify the signature that accompanies a package,
    you must first have the vendor, organisation, or issueing person's
    key imported into your public keyring. To prevent GnuPG warning
    messages the key should also be validated (or locally signed).

    You will also need to download the detached signature file along
    with the package. These files will usually have the same name as
    the package, with either a binary (.sig) or ASCII armor (.asc)
    extension.

    Once their key has been imported, and the package and accompanying
    signature files have been downloaded, use:

       $ gpg --verify sigfile signed-file

    If the signature file has the same base name as the package file,
    the package can also be verified by specifying just the signature
    file, as GnuPG will derive the package's file name from the name
    given (less the .sig or .asc extension). For example, to verify a
    package named foobar.tar.gz against its detached binary signature
    file, use:

       $ gpg --verify foobar.tar.gz.sig

4.20) How do I export a keyring with only selected signatures (keys)?

    If you're wanting to create a keyring with only a subset of keys
    selected from a master keyring (for a club, user group, or company
    department for example), simply specify the keys you want to export:

       $ gpg --armor --export key1 key2 key3 key4 > keys1-4.asc

4.21) I still have my secret key, but lost my public key. What can I do?

    All OpenPGP secret keys have a copy of the public key inside them,
    and in a worst-case scenario, you can create yourself a new public
    key using the secret key.

    A tool to convert a secret key into a public one has been included
    (it's actually a new option for gpgsplit) and is available with GnuPG
    versions 1.2.1 or later (or can be found in CVS). It works like this:

       $ gpgsplit --no-split --secret-to-public secret.gpg >publickey.gpg

    One should first try to export the secret key and convert just this
    one. Using the entire secret keyring should work too. After this has
    been done, the publickey.gpg file can be imported into GnuPG as usual.

4.22) Clearsigned messages sent from my web-mail account have an invalid
    signature. Why?

    Check to make sure the settings for your web-based email account
    do not use HTML formatting for the pasted clearsigned message. This can
    alter the message with embedded HTML markup tags or spaces, resulting
    in an invalid signature. The recipient may be able to copy the signed
    message block to a text file for verification, or the web email
    service may allow you to attach the clearsigned message as a file
    if plaintext messages are not an option.


5. COMPATIBILITY ISSUES

5.1) How can I encrypt a message with GnuPG so that PGP is able to decrypt it?

    It depends on the PGP version.

    PGP 2.x
    You can't do that because PGP 2.x normally uses IDEA which is not
    supported by GnuPG as it is patented (see 3.3), but if you have a
    modified version of PGP you can try this:

       $ gpg --rfc1991 --cipher-algo 3des ...

    Please don't pipe the data to encrypt to gpg but provide it using a
    filename; otherwise, PGP 2 will not be able to handle it.

    As for conventional encryption, you can't do this for PGP 2.

    PGP 5.x and higher
    You need to provide two additional options:

       --compress-algo 1 --cipher-algo cast5

    You may also use "3des" instead of "cast5", and "blowfish" does not
    work with all versions of PGP 5. You may also want to put:

       compress-algo 1

    into your ~/.gnupg/options file - this does not affect normal GnuPG
    operation.

    This applies to conventional encryption as well.

5.2) How do I migrate from PGP 2.x to GnuPG?

    PGP 2 uses the RSA and IDEA encryption algorithms. Whereas the RSA
    patent has expired and RSA is included as of GnuPG 1.0.3, the IDEA
    algorithm is still patented until 2007. Under certain conditions you
    may use IDEA even today. In that case, you may refer to Question
    3.3 about how to add IDEA support to GnuPG and read
    <http://www.gnupg.org/gph/en/pgp2x.html> to perform the migration.

5.3) (removed)

    (empty)

5.4) Why is PGP 5.x not able to encrypt messages with some keys?

    PGP, Inc. refuses to accept Elgamal keys of type 20 even for
    encryption. They only support type 16 (which is identical at least
    for decryption). To be more inter-operable, GnuPG (starting with
    version 0.3.3) now also uses type 16 for the Elgamal subkey which is
    created if the default key algorithm is chosen. You may add a type
    16 Elgamal key to your public key, which is easy as your key
    signatures are still valid.

5.5) Why is PGP 5.x not able to verify my messages?

    PGP 5.x does not accept v4 signatures for data material but OpenPGP
    requests generation of v4 signatures for all kind of data, that's why
    GnuPG defaults to them. Use the option "--force-v3-sigs" to generate
    v3 signatures for data.

5.6) How do I transfer owner trust values from PGP to GnuPG?

    There is a script in the tools directory to help you. After you have
    imported the PGP keyring you can give this command:

       $ lspgpot pgpkeyring | gpg --import-ownertrust

    where pgpkeyring is the original keyring and not the GnuPG keyring
    you might have created in the first step.

5.7) PGP does not like my secret key.

    Older PGPs probably bail out on some private comment packets used by
    GnuPG. These packets are fully in compliance with OpenPGP; however
    PGP is not really OpenPGP aware. A workaround is to export the
    secret keys with this command:

       $ gpg --export-secret-keys --no-comment -a your-KeyID

    Another possibility is this: by default, GnuPG encrypts your secret
    key using the Blowfish symmetric algorithm. Older PGPs will only
    understand 3DES, CAST5, or IDEA symmetric algorithms. Using the
    following method you can re-encrypt your secret gpg key with a
    different algo:

       $ gpg --s2k-cipher-algo=CAST5 --s2k-digest-algo=SHA1
         --compress-algo=1  --edit-key <username>

    Then use passwd to change the password (just change it to the same
    thing, but it will encrypt the key with CAST5 this time).

    Now you can export it and PGP should be able to handle it.

    For PGP 6.x the following options work to export a key:

       $ gpg --s2k-cipher-algo 3des --compress-algo 1 --rfc1991
         --export-secret-keys <KeyID>

5.8) GnuPG no longer installs a ~/.gnupg/options file. Is it missing?

    No. The ~/.gnupg/options file has been renamed to ~/.gnupg/gpg.conf for
    new installs as of version 1.1.92. If an existing ~/.gnupg/options file
    is found during an upgrade it will still be used, but this change was
    required to have a more consistent naming scheme with forthcoming tools.
    An existing options file can be renamed to gpg.conf for users upgrading,
    or receiving the message that the "old default options file" is ignored
    (occurs if both a gpg.conf and an options file are found).

5.9) How do you export GnuPG keys for use with PGP?

    This has come up fairly often, so here's the HOWTO:

    PGP can (for most key types) use secret keys generated by GnuPG. The
    problems that come up occasionally are generally because GnuPG
    supports a few more features from the OpenPGP standard than PGP does.
    If your secret key has any of those features in use, then PGP will
    reject the key or you will have problems communicating later. Note
    that PGP doesn't do Elgamal signing keys at all, so they are not
    usable with any version.

    These instructions should work for GnuPG 1.0.7 and later, and PGP
    7.0.3 and later.

    Start by editing the key. Most of this line is not really necessary
    as the default values are correct, but it does not hurt to repeat the
    values, as this will override them in case you have something else set
    in your options file.

       $ gpg --s2k-cipher-algo cast5 --s2k-digest-algo sha1 --s2k-mode 3
         --simple-sk-checksum --edit KeyID

    Turn off some features. Set the list of preferred ciphers, hashes,
    and compression algorithms to things that PGP can handle. (Yes, I
    know this is an odd list of ciphers, but this is what PGP itself uses,
    minus IDEA).

       > setpref S9 S8 S7 S3 S2 S10 H2 H3 Z1 Z0

    Now put the list of preferences onto the key.

       > updpref

    Finally we must decrypt and re-encrypt the key, making sure that we
    encrypt with a cipher that PGP likes. We set this up in the --edit
    line above, so now we just need to change the passphrase to make it
    take effect. You can use the same passphrase if you like, or take
    this opportunity to actually change it.

       > passwd

    Save our work.

       > save

    Now we can do the usual export:

       $ gpg --export KeyID > mypublickey.pgp
       $ gpg --export-secret-key KeyID > mysecretkey.pgp

    Thanks to David Shaw for this information!


6. PROBLEMS and ERROR MESSAGES

6.1) Why do I get "gpg: Warning: using insecure memory!"

    On many systems this program should be installed as setuid(root).
    This is necessary to lock memory pages. Locking memory pages prevents
    the operating system from writing them to disk and thereby keeping your
    secret keys really secret. If you get no warning message about insecure
    memory your operating system supports locking without being root. The
    program drops root privileges as soon as locked memory is allocated.

    To setuid(root) permissions on the gpg binary you can either use:

       $ chmod u+s /path/to/gpg

    or

       $ chmod 4755 /path/to/gpg

    Some refrain from using setuid(root) unless absolutely required for
    security reasons. Please check with your system administrator if you
    are not able to make these determinations yourself. 

    On UnixWare 2.x and 7.x you should install GnuPG with the 'plock'
    privilege to get the same effect:

       $ filepriv -f plock /path/to/gpg

    If you can't or don't want to install GnuPG setuid(root), you can
    use the option "--no-secmem-warning" or put:

       no-secmem-warning

    in your ~/.gnupg/options or ~/.gnupg/gpg.conf file (this disables
    the warning).

    On some systems (e.g., Windows) GnuPG does not lock memory pages
    and older GnuPG versions (<=1.0.4) issue the warning:

       gpg: Please note that you don't have secure memory

    This warning can't be switched off by the above option because it
    was thought to be too serious an issue. However, it confused users
    too much, so the warning was eventually removed.

6.2) Large File Support doesn't work ...

    LFS works correctly in post-1.0.4 versions. If configure doesn't
    detect it, try a different (i.e., better) compiler. egcs 1.1.2 works
    fine, other gccs sometimes don't. BTW, several compilation problems
    of GnuPG 1.0.3 and 1.0.4 on HP-UX and Solaris were due to broken LFS
    support.

6.3) In the edit menu the trust values are not displayed correctly after
    signing uids. Why?

    This happens because some information is stored immediately in
    the trustdb, but the actual trust calculation can be done after the
    save command. This is a "not easy to fix" design bug which will be
    addressed in some future release.

6.4) What does "skipping pubkey 1: already loaded" mean?

    As of GnuPG 1.0.3, the RSA algorithm is included. If you still have
    a "load-extension rsa" in your options file, the above message
    occurs. Just remove the load command from the options file.

6.5) GnuPG 1.0.4 doesn't create ~/.gnupg ...

    That's a known bug, already fixed in newer versions.

6.6) An Elgamal signature does not verify anymore since version 1.0.2 ...

    Use the option --emulate-md-encode-bug.

6.7) Old versions of GnuPG can't verify Elgamal signatures

    Update to GnuPG 1.0.2 or newer.

6.8) When I use --clearsign, the plain text has sometimes extra dashes
    in it - why?

    This is called dash-escaped text and is required by OpenPGP.
    It always happens when a line starts with a dash ("-") and is
    needed to make the lines that structure signature and text
    (i.e., "-----BEGIN PGP SIGNATURE-----") to be the only lines
    that start with two dashes.

    If you use GnuPG to process those messages, the extra dashes
    are removed. Good mail clients remove those extra dashes when
    displaying such a message.      

6.9) What is the thing with "can't handle multiple signatures"?

    Due to different message formats GnuPG is not always able to split
    a file with multiple signatures unambiguously into its parts. This
    error message informs you that there is something wrong with the input.

    The only way to have multiple signatures in a file is by using the
    OpenPGP format with one-pass-signature packets (which is GnuPG's
    default) or the cleartext signed format.

6.10) If I submit a key to a keyserver, nothing happens ...

    You are most likely using GnuPG 1.0.2 or older on Windows. That's
    feature isn't yet implemented, but it's a bug not to say it. Newer
    versions issue a warning. Upgrade to 1.0.4 or newer.

6.11) I get "gpg: waiting for lock ..."

    A previous instance of gpg has most likely exited abnormally and left
    a lock file. Go to ~/.gnupg and look for .*.lock files and remove them.

6.12) Older gpg binaries (e.g., 1.0) have problems with keys from newer
    gpg binaries ...

    As of 1.0.3, keys generated with gpg are created with preferences to
    TWOFISH (and AES since 1.0.4) and that also means that they have the
    capability to use the new MDC encryption method. This will go into
    OpenPGP soon, and is also suppoted by PGP 7. This new method avoids
    a (not so new) attack on all email encryption systems.

    This in turn means that pre-1.0.3 gpg binaries have problems with
    newer keys. Because of security and bug fixes, you should keep your
    GnuPG installation in a recent state anyway. As a workaround, you can
    force gpg to use a previous default cipher algo by putting:

       cipher-algo cast5

    into your options file.

6.13) With 1.0.4, I get "this cipher algorithm is deprecated ..."

    If you just generated a new key and get this message while
    encrypting, you've witnessed a bug in 1.0.4. It uses the new AES
    cipher Rijndael that is incorrectly being referred as "deprecated".
    Ignore this warning, more recent versions of gpg are corrected.

6.14) Some dates are displayed as ????-??-??. Why?

    Due to constraints in most libc implementations, dates beyond
    2038-01-19 can't be displayed correctly. 64-bit OSes are not
    affected by this problem. To avoid printing wrong dates, GnuPG
    instead prints some question marks. To see the correct value, you
    can use the options --with-colons and --fixed-list-mode.

6.15) I still have a problem. How do I report a bug?

    Are you sure that it's not been mentioned somewhere on the mailing
    lists? Did you have a look at the bug list (you'll find a link to
    the list of reported bugs on the documentation page). If you're not
    sure about it being a bug, you can send mail to the gnupg-devel
    list. Otherwise, use the GUUG bug tracking system 
    <http://bugs.guug.de/Reporting.html>.

6.16) Why doesn't GnuPG support X.509 certificates?

    GnuPG, first and foremost, is an implementation of the OpenPGP
    standard (RFC 2440), which is a competing infrastructure, different
    from X.509.

    They are both public-key cryptosystems, but how the public keys are
    actually handled is different.

6.17) Why do national characters in my user ID look funny?

    According to OpenPGP, GnuPG encodes user ID strings (and other
    things) using UTF-8. In this encoding of Unicode, most national
    characters get encoded as two- or three-byte sequences. For
    example, &aring; (0xE5 in ISO-8859-1) becomes &Atilde;&yen; (0xC3,
    0xA5). This might also be the reason why keyservers can't find
    your key.

6.18) I get 'sed' errors when running ./configure on Mac OS X ...

    This will be fixed after GnuPG has been upgraded to autoconf-2.50.
    Until then, find the line setting CDPATH in the configure script
    and place an:

       unset CDPATH

    statement below it.

6.19) Why does GnuPG 1.0.6 bail out on keyrings used with 1.0.7?

    There is a small bug in 1.0.6 which didn't parse trust packets
    correctly. You may want to apply this patch if you can't upgrade:

    <http://www.gnupg.org/developer/gpg-woody-fix.txt>

6.20) I upgraded to GnuPG version 1.0.7 and now it takes longer to load my
    keyrings. What can I do?

    The way signature states are stored has changed so that v3 signatures
    can be supported. You can use the new --rebuild-keydb-caches migration
    command, which was built into this release and increases the speed of
    many operations for existing keyrings.

6.21) Doesn't a fully trusted user ID on a key prevent warning messages
    when encrypting to other IDs on the key?

    No. That was actually a key validity bug in GnuPG 1.2.1 and earlier
    versions. As part of the development of GnuPG 1.2.2, a bug was
    discovered in the key validation code.  This bug causes keys with
    more than one user ID to give all user IDs on the key the amount of
    validity given to the most-valid key. The bug has been fixed in GnuPG
    release 1.2.2, and upgrading is the recommended fix for this problem.
    More information and a patch for a some pre-1.2.2 versions of GnuPG
    can be found at:

    <http://lists.gnupg.org/pipermail/gnupg-announce/2003q2/000268.html>

6.22) I just compiled GnuPG from source on my GNU/Linux RPM-based system
    and it's not working. Why?

    Many GNU/Linux distributions that are RPM-based will install a
    version of GnuPG as part of its standard installation, placing the
    binaries in the /usr/bin directory. Later, compiling and installing
    GnuPG from source other than from a source RPM won't normally
    overwrite these files, as the default location for placement of
    GnuPG binaries is in /usr/local/bin unless the '--prefix' switch
    is used during compile to specify an alternate location. Since the
    /usr/bin directory more than likely appears in your path before
    /usr/local/bin, the older RPM-version binaries will continue to
    be used when called since they were not replaced.

    To resolve this, uninstall the RPM-based version with 'rpm -e gnupg'
    before installing the binaries compiled from source. If dependency
    errors are displayed when attempting to uninstall the RPM (such as
    when Red Hat's up2date is also installed, which uses GnuPG), uninstall
    the RPM with 'rpm -e gnupg --nodeps' to force the uninstall. Any
    dependent files should be automatically replaced during the install
    of the compiled version. If the default /usr/local/bin directory is
    used, some packages such as SuSE's Yast Online Update may need to be
    configured to look for GnuPG binaries in the /usr/local/bin directory,
    or symlinks can be created in /usr/bin that point to the binaries
    located in /usr/local/bin.


7. ADVANCED TOPICS

7.1) How does this whole thing work?

    To generate a secret/public keypair, run:

       $ gpg --gen-key

    and choose the default values.

    Data that is encrypted with a public key can only be decrypted by
    the matching secret key. The secret key is protected by a password,
    the public key is not.

    So to send your friend a message, you would encrypt your message
    with his public key, and he would only be able to decrypt it by
    having the secret key and putting in the password to use his secret
    key.

    GnuPG is also useful for signing things. Files that are encrypted
    with the secret key can be decrypted with the public key. To sign
    something, a hash is taken of the data, and then the hash is in some
    form encoded with the secret key. If someone has your public key, they
    can verify that it is from you and that it hasn't changed by checking
    the encoded form of the hash with the public key.

    A keyring is just a large file that stores keys. You have a public
    keyring where you store yours and your friend's public keys. You have
    a secret keyring that you keep your secret key on, and should be very
    careful with. Never ever give anyone else access to it and use a *good*
    passphrase to protect the data in it.

    You can 'conventionally' encrypt something by using the option 'gpg -c'.
    It is encrypted using a passphrase, and does not use public and secret
    keys. If the person you send the data to knows that passphrase, they
    can decrypt it. This is usually most useful for encrypting things to
    yourself, although you can encrypt things to your own public key in the
    same way. It should be used for communication with partners you know
    and where it is easy to exchange the passphrases (e.g. with your boy
    friend or your wife). The advantage is that you can change the
    passphrase from time to time and decrease the risk, that many old
    messages may be decrypted by people who accidently got your passphrase.

    You can add and copy keys to and from your keyring with the 'gpg
    --import' and 'gpg --export' command. 'gpg --export-secret-keys' will
    export secret keys. This is normally not useful, but you can generate
    the key on one machine then move it to another machine.

    Keys can be signed under the 'gpg --edit-key' option. When you sign a
    key, you are saying that you are certain that the key belongs to the
    person it says it comes from. You should be very sure that is really
    that person: You should verify the key fingerprint with:

       $ gpg --fingerprint KeyID

    over the phone (if you really know the voice of the other person), at
    a key signing party (which are often held at computer conferences),
    or at a meeting of your local GNU/Linux User Group.

    Hmm, what else. You may use the option '-o filename' to force output
    to this filename (use '-' to force output to stdout). '-r' just lets
    you specify the recipient (which public key you encrypt with) on the
    command line instead of typing it interactively.

    Oh yeah, this is important. By default all data is encrypted in some
    weird binary format. If you want to have things appear in ASCII text
    that is readable, just add the '-a' option. But the preferred method
    is to use a MIME aware mail reader (Mutt, Pine and many more).

    There is a small security glitch in the OpenPGP (and therefore GnuPG)
    system; to avoid this you should always sign and encrypt a message
    instead of only encrypting it.

7.2) Why are some signatures with an ELG-E key valid?

    These are Elgamal keys generated by GnuPG in v3 (RFC 1991) packets.
    The OpenPGP draft later changed the algorithm identifier for Elgamal
    keys which are usable for signatures and encryption from 16 to 20.
    GnuPG now uses 20 when it generates new Elgamal keys but still
    accepts 16 (which is according to OpenPGP "encryption only") if this
    key is in a v3 packet. GnuPG is the only program which had used
    these v3 Elgamal keys - so this assumption is quite safe.

7.3) How does the whole trust thing work?

    It works more or less like PGP. The difference is that the trust is
    computed at the time it is needed. This is one of the reasons for
    the trustdb which holds a list of valid key signatures. If you are
    not running in batch mode you will be asked to assign a trust
    parameter (ownertrust) to a key.

    You can see the validity (calculated trust value) using this
    command.

       $ gpg --list-keys --with-colons

    If the first field is "pub" or "uid", the second field shows you the
    trust:

       o = Unknown (this key is new to the system)
       e = The key has expired
       q = Undefined (no value assigned)
       n = Don't trust this key at all
       m = There is marginal trust in this key
       f = The key is full trusted
       u = The key is ultimately trusted; this is only used
           for keys for which the secret key is also available.
       r = The key has been revoked
       d = The key has been disabled

    The value in the "pub" record is the best one of all "uid" records.
    You can get a list of the assigned trust values (how much you trust
    the owner to correctly sign another person's key) with:

       $ gpg --list-ownertrust

    The first field is the fingerprint of the primary key, the second
    field is the assigned value:

       - = No ownertrust value yet assigned or calculated.
       n = Never trust this keyholder to correctly verify others signatures.
       m = Have marginal trust in the keyholders capability to sign other
           keys.
       f = Assume that the key holder really knows how to sign keys.
       u = No need to trust ourself because we have the secret key.

    Keep these values confidential because they express your opinions
    about others. PGP stores this information with the keyring thus it
    is not a good idea to publish a PGP keyring instead of exporting the
    keyring. GnuPG stores the trust in the trustdb.gpg file so it is okay
    to give a gpg keyring away (but we have a --export command too).

7.4) What kind of output is this: "key C26EE891.298, uid 09FB: ...."?

    This is the internal representation of a user ID in the trustdb.
    "C26EE891" is the keyid, "298" is the local ID (a record number in
    the trustdb) and "09FB" is the last two bytes of a ripe-md-160 hash
    of the user ID for this key.

7.5) How do I interpret some of the informational outputs?

    While checking the validity of a key, GnuPG sometimes prints some
    information which is prefixed with information about the checked
    item.

       "key 12345678.3456"

    This is about the key with key ID 12345678 and the internal number
    3456, which is the record number of the so called directory record
    in the trustdb.

       "uid 12345678.3456/ACDE"

    This is about the user ID for the same key. To identify the user ID
    the last two bytes of a ripe-md-160 over the user ID ring is printed.

       "sig 12345678.3456/ACDE/9A8B7C6D"

    This is about the signature with key ID 9A8B7C6D for the above key
    and user ID, if it is a signature which is direct on a key, the user
    ID part is empty (..//..).

7.6) Are the header lines of a cleartext signature part of the signed
    material?

    No. For example you can add or remove "Comment:" lines. They have
    a purpose like the mail header lines. However a "Hash:" line is
    needed for OpenPGP signatures to tell the parser which hash
    algorithm to use.

7.7) What is the list of preferred algorithms?

    The list of preferred algorithms is a list of cipher, hash and
    compression algorithms stored in the self-signature of a key during
    key generation. When you encrypt a document, GnuPG uses this list
    (which is then part of a public key) to determine which algorithms
    to use. Basically it tells other people what algorithms the
    recipient is able to handle and provides an order of preference.

7.8) How do I change the list of preferred algorithms?

    In version 1.0.7 or later, you can use the edit menu and set the
    new list of preference using the command "setpref"; the format of
    this command resembles the output of the command "pref". The
    preference is not changed immediately but the set preference will
    be used when a new user ID is created. If you want to update the
    preferences for existing user IDs, select those user IDs (or select
    none to update all) and enter the command "updpref". Note that the
    timestamp of the self-signature is increased by one second when
    running this command.


8. ACKNOWLEDGEMENTS

    Many thanks to Nils Ellmenreich for maintaining this FAQ file for
    such a long time, Werner Koch for the original FAQ file, and to all
    posters to gnupg-users and gnupg-devel. They all provided most of
    the answers.

    Also thanks to Casper Dik for providing us with a script to generate
    this FAQ (he uses it for the excellent Solaris2 FAQ).


Copyright (C) 2000, 2001, 2002, 2003 Free Software Foundation, Inc.,

Verbatim copying and distribution of this entire article is permitted in
any medium, provided this notice is preserved.
