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This is the DETAILS file for GnuPG which specifies some internals and parts of the external API for GPG and GPGSM.
The format is a based on colon separated record, each recods starts with a tag string and extends to the end of the line. Here is an example:
$ gpg --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. Old versions of gpg used a slightly different format and required
the use of the option --fixed-list-mode to conform to the format
described here.
- 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 [*]
- grp
- Keygrip
- rvk
- Revocation key
- tru
- Trust database information [*]
- spk
- Signature subpacket [*]
- cfg
- Configuration data [*]
Records marked with an asterisk are described at *Special fields.
This is a letter describing the computed validity of a key. Currently this is a single letter, but be prepared that additional information may follow in some future versions. Note that GnuPG < 2.1 does not set this field for secret key listings.
- 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- The key has been revoked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 validity (i.e. no value assigned)
- q
- Undefined validity. ‘-’ and ‘q’ may safely be treated as the same value for most purposes
- n
- The key is not valid
- m
- The key is marginal valid.
- f
- The key is fully valid
- u
- The key is ultimately valid. This often means that the secret key is available, but any key may be marked as ultimately valid.
- w
- The key has a well known private part.
- s
- The key has special validity. This means that it might be self-signed and expected to be used in the STEED sytem.
If the validity information is given for a UID or UAT record, it describes the validity calculated based on this user ID. If given for a key record it describes the validity taken from the best rated user ID.
For X.509 certificates a ‘u’ is used for a trusted root certificate (i.e. for the trust anchor) and an ‘f’ for all other valid certificates.
The length of key in bits.
The values here are those from the OpenPGP specs or if they are greather than 255 the algorithm ids as used by Libgcrypt.
This is the 64 bit keyid as specified by OpenPGP and the last 64 bit of the SHA-1 fingerprint of an X.509 certifciate.
The creation date of the key is given in UTC. For UID and UAT
records, this is used for the self-signature date. Note that the
date 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 new
format is to scan for the ‘T’. Note that old versions of gpg
without using the --fixed-list-mode option used a “yyyy-mm-tt”
format.
Key or UID/UAT expiration date or empty if it does not expire.
Used for serial number in crt records. 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.
This is only used on primary keys. This is a single letter, but be prepared that additional information may follow in future versions. For trust signatures with a regular expression, this is the regular expression value, quoted as in field 10.
The value is quoted like a C string to avoid control characters
(the colon is quoted \x3a). For a “pub” record this field is
not used on –fixed-list-mode. 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. A FPR
record stores the fingerprint here. The fingerprint of a
revocation key is stored here.
Signature class as per RFC-4880. 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’ is used the same way. This field if not used for X.509.
The defined capabilities are:
- e
- Encrypt
- s
- Sign
- c
- Certify
- a
- Authentication
- ?
- Unknown capability
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.
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 key database it is only filled if the issuer certificate is available. The root has been reached if this is the same string as the fingerprint. 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” records this field lists the preferences in the same way gpg’s –edit-key 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.
Flag field used in the –edit menu output
Used in sec/ssb 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). If the option –with-secret is used and a secret key is available for the public key, a ‘+’ indicates this.
For sig records, this is the used hash algorithm. For example: 2 = SHA-1, 8 = SHA-256.
For pub, sub, sec, and ssb records this field is used for the ECC curve name.
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)
Example for a “tru” trust base record:
tru:o:0:1166697654:1:3:1:5
- Field 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.
- Field 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.
- Field 4
- Date trustdb was created in seconds since Epoch.
- Field 5
- Date trustdb will expire in seconds since Epoch.
- Field 6
- Number of marginally trusted users to introduce a new key signer (gpg’s option –marginals-needed).
- Field 7
- Number of completely trusted users to introduce a new key signer. (gpg’s option –completes-needed)
- Field 8
- Maximum depth of a certification chain. (gpg’s option –max-cert-depth)
- Field 2
- Subpacket number as per RFC-4880 and later.
- Field 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.
- Field 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.
- Field 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.
–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 algorithms
this version of GnuPG supports, separated by
semicolons. The algorithm numbers are as specified in
RFC-4880. Note that in contrast to the –status-fd
interface these are not the Libgcrypt identifiers.
Using
pubkeynameprints names instead of numbers.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-4880.
Using
ciphernameprints names instead of numbers.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-4880. Using
digestnameprints names instead of numbers.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-4880.
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 pattiwould result in:
cfg:group:mynames:patti;joe;0x12345678;paige - curve
- The third field contains the curve names this version
of GnuPG supports, separated by semicolons. Using
curveoidprints OIDs instead of numbers.cfg:curve:ed25519;nistp256;nistp384;nistp521
Every line is prefixed with “[GNUPG:] “, followed by a keyword with the type of the status line and some arguments depending on the type (maybe none); an application should always be prepared to see more arguments in future versions.
Is issued right before a signature verification starts. This is useful to define a context for parsing ERROR status messages. No arguments are currently defined.
The signature with the keyid is good. For each signature only one of the codes GOODSIG, BADSIG, EXPSIG, EXPKEYSIG, REVKEYSIG or ERRSIG will be emitted. In the past they were used as a marker for a new signature; new code should use the NEWSIG status instead. The username is the primary one encoded in UTF-8 and %XX escaped. The fingerprint may be used instead of the long keyid if it is available. This is the case with CMS and might eventually also be available for OpenPGP.
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. The fingerprint may be used instead of the long keyid if it is available. This is the case with CMS and might eventually also be available for OpenPGP.
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. The fingerprint may be used instead of the long keyid if it is available. This is the case with CMS and might eventually also be available for OpenPGP.
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. The fingerprint may be used instead of the long keyid if it is available. This is the case with CMS and might eventually also beñ available for OpenPGP.
The signature with the keyid has not been verified okay. The username is the primary one encoded in UTF-8 and %XX escaped. The fingerprint may be used instead of the long keyid if it is available. This is the case with CMS and might eventually also be available for OpenPGP.
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. The fingerprint may be used instead of the keyid if it is available. This is the case with gpgsm and might eventually also be available for OpenPGP.
Note, that TIME may either be the number of seconds since Epoch or an ISO 8601 string. The latter can be detected by the presence of the letter ‘T’.
The args are:
- <fingerprint_in_hex>
- <sig_creation_date>
- <sig-timestamp>
- <expire-timestamp>
- <sig-version>
- <reserved>
- <pubkey-algo>
- <hash-algo>
- <sig-class>
- [ <primary-key-fpr> ]
This status indicates that the signature is cryptographically valid. This is similar to GOODSIG, EXPSIG, EXPKEYSIG, or REVKEYSIG (depending on the date and the state of the signature and signing key) but has the fingerprint as the argument. Multiple status lines (VALIDSIG and the other appropriate *SIG status) are emitted for a valid 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.
The primary-key-fpr parameter is used for OpenPGP and not available for CMS signatures. The sig-version as well as the sig class is not defined for CMS and currently set to 0 and 00.
Note, that *-TIMESTAMP may either be a number of seconds since Epoch or an ISO 8601 string which can be detected by the presence of the letter ‘T’.
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 of seconds since Epoch or an ISO 8601 string which can be detected by the presence of the letter ‘T’.
The message is encrypted to this LONG_KEYID. KEYTYPE is the numerical value of the public key algorithm or 0 if it is not known, KEYLENGTH is the length of the key or 0 if it is not known (which is currently always the case). Gpg prints this line always; Gpgsm only if it knows the certificate.
Mark the start of the actual decryption process. This is also emitted when in –list-only mode.
Mark the end of the actual decryption process. This are also emitted when in –list-only mode.
Print information about the symmetric encryption algorithm and the MDC method. This will be emitted even if the decryption fails.
The symmetric decryption failed - one reason could be a wrong passphrase for a symmetrical encrypted message.
The decryption process succeeded. This means, that either the correct secret key has been used or the correct passphrase for a symmetric encrypted message was given. The program itself may return an errorcode because it may not be possible to verify a signature for some reasons.
The session key used to decrypt the message. This message will only be emitted if the option –show-session-key is used. The format is suitable to be passed as value for the option –override-session-key. It is not an indication that the decryption will or has succeeded.
Mark the start of the actual encryption process.
Mark the end of the actual encryption process.
Start processing a file <filename>. <what> indicates the performed operation:
- 1
- verify
- 2
- encrypt
- 3
- decrypt
Marks the end of a file processing which has been started by FILE_START.
Mark the start of the actual signing process. This may be used as an indication that all requested secret keys are ready for use.
Warning: This is experimental and might be removed at any time.
A signature has been created using these parameters. Values for type <type> are:
- D
- detached
- C
- cleartext
- S
- standard
(only the first character should be checked)
<class> are 2 hex digits with the OpenPGP signature class.
Note, that TIMESTAMP may either be a number of seconds since Epoch or an ISO 8601 string which can be detected by the presence of the letter ‘T’.
There are actually two related status codes to convey notation data:
- NOTATION_NAME <name>
- NOTATION_DATA <string>
<name> and <string> are %XX escaped; the data may be split among several NOTATION_DATA lines.
Note that URL in <string> is %XX escaped.
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.
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.
The list or argemnts are:
- <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 (e.g. 1 for an image). <index> and <count> indicate that this is the N-th 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
This indicates that a signature subpacket was seen. The format is the same as the “spk” record above.
The two similar status codes:
- INV_RECP <reason> <requested_recipient>
- INV_SGNR <reason> <requested_sender>
are issued for each unusable recipient/sender. 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
- 11
- Missing certificate
- 12
- Missing issuer certificate
- 13
- Key disabled
- 14
- Syntax error in specification
Note that for historical reasons the INV_RECP status is also used for gpgsm’s SIGNER command where it relates to signer’s of course. Newer GnuPG versions are using INV_SGNR; applications should ignore the INV_RECP during the sender’s command processing once they have seen an INV_SGNR. Different codes are used so that they can be distinguish while doing an encrypt+sign operation.
Issued if no recipients are usable.
Issued if no senders are usable.
The key has expired. expire-timestamp is the expiration time in seconds since Epoch. This status line is not very useful because it will also be emitted for expired subkeys even if this subkey is not used. To check whether a key used to sign a message has expired, the EXPKEYSIG status line is to be used.
Note, that the TIMESTAMP may either be a number of seconds since Epoch or an ISO 8601 string which can be detected by the presence of the letter ‘T’.
The used key has been revoked by its owner. No arguments yet.
The public key is not available
The secret key is not available
A key has been created. Values for <type> are:
- 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.
The key from batch run has not been created due to errors.
These are several similar status codes:
- TRUST_UNDEFINED <error_token>
- TRUST_NEVER <error_token>
- TRUST_MARGINAL [0 [<validation_model>]]
- TRUST_FULLY [0 [<validation_model>]]
- TRUST_ULTIMATE [0 [<validation_model>]]
For good signatures one of these status lines are emitted to indicate the validity of the key used to create the signature. The error token values are currently only emitted by gpgsm.
VALIDATION_MODEL describes the algorithm used to check the validity of the key. The defaults are the standard Web of Trust model for gpg and the the standard X.509 model for gpgsm. The defined values are
- pgp
- The standard PGP WoT.
- shell
- The standard X.509 model.
- chain
- The chain model.
- steed
- The STEED model.
Note that the term TRUST_ in the status names is used for
historic reasons; we now speak of validity.
This is is one:
- 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.
GET_BOOL, GET_LINE, GET_HIDDEN, GOT_IT
These status line are used with –command-fd for interactive control of the process.
Give a hint about the user ID for a certain keyID.
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).
Issued whenever a passphrase for symmetric encryption is needed.
Issued whenever a PIN is requested to unlock a card.
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.
The supplied passphrase was wrong or not given. In the latter case you may have seen a MISSING_PASSPHRASE.
The supplied passphrase was good and the secret key material is therefore usable.
This status is emitted in interactive mode right before the “import.okay” prompt.
The keyid and name of the signature just imported
The key with the primary key’s FINGERPRINT has been imported. REASON flags are:
- 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.
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.
Final statistics on import process (this is one long line). The args are a list of unsigned numbers separated by white space:
- <count>
- <no_user_id>
- <imported>
- always 0 (formerly used for the number of RSA keys)
- <unchanged>
- <n_uids>
- <n_subk>
- <n_sigs>
- <n_revoc>
- <sec_read>
- <sec_imported>
- <sec_dups>
- <skipped_new_keys>
- <not_imported>
- <skipped_v3_keys>
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. Used by gpg 1.4 w/o scdaemon
- 2
- Request removal of a card. Used by gpg 1.4 w/o scdaemon.
- 3
- Card with serialnumber detected
- 4
- No card available
- 5
- No card reader available
- 6
- No card support available
- 7
- Card is in termination state
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
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.
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 data has been encountered. Codes for WHAT are:
- 0
- Not further specified
- 1
- Corrupted message structure
The output was truncated to MAXNO items. This status code is issued for certain external requests.
This is a generic error status message, it might be followed by error location specific data. <error code> and <error_location> should not contain spaces. The error code is a either a string commencing with a letter or such a string prefixed with a numerical error code and an underscore; e.g.: “151011327_EOF”.
Postive confirmation that an operation succeeded. It is used similar to ISO-C’s EXIT_SUCCESS. <location> is optional but if given should not contain spaces. Used only with a few commands.
This is the counterpart to SUCCESS and used to indicate a program failure. It is used similar to ISO-C’s EXIT_FAILURE but allows to convey more information, in particular an gpg-error error code. That numerical error code may optionally have a suffix made of an underscore and a string with an error symbol like “151011327_EOF”. A dash may be used instead of <location>.
The ASCII armor is corrupted. No arguments yet.
Deleting a key failed. Reason codes are:
- 1
- No such key
- 2
- Must delete secret key first
- 3
- Ambigious specification
- 4
- Key is stored on a smartcard.
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. The condition
TOTAL && CUR == TOTAL
may be used to detect the end of an operation.
Well known values for WHAT are:
- pk_dsa
- DSA key generation
- pk_elg
- Elgamal key generation
- primegen
- Prime generation
- need_entropy
- Waiting for new entropy in the RNG
- 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.
- learncard
- Send by the agent and gpgsm while learing the data of a smartcard.
- card_busy
- A smartcard is still working
A backup of a key identified by <fingerprint> has been writte to the file <fname>; <fname> is percent-escaped.
<name> is a percent-plus escaped filename describing the mountpoint for the current operation (e.g. used by “g13 –mount”). This may either be the specified mountpoint or one randomly choosen by g13.
This status line is emitted by gpg to notify a client that a Pinentry has been launched. <pid> is the PID of the Pinentry. It may be used to display a hint to the user but can’t be used to synchronize with Pinentry. Note that there is also an Assuan inquiry line with the same name used internally or, if enabled, send to the client instead of this status line. Such an inquiry may be used to sync with Pinentry
Removed on 2011-02-04. This is deprecated in favor of KEYEXPIRED.
Obsolete. This status message used to be emitted for requests to use the IDEA or RSA algorithms. It has been dropped from GnuPG 2.1 after the respective patents expired.
SHM_INFO, SHM_GET, SHM_GET_BOOL, SHM_GET_HIDDEN
These were used for the ancient shared memory based co-processing.
Used to issued by the experimental pipemode.
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 RFC 4880. 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.
Please see the GnuPG manual for a description.
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.
The record types: directory(2), key(3), uid(4), pref(5), sigrec(6), and shadow directory(8) are not anymore used by version 2 of the TrustDB.
Unused record or deleted, can be reused for any purpose. Such records should in general not exist because deleted records are of type 254 and kept in a linked list.
Version information for this TrustDB. This is always the first record of the DB and the only one of this type.
- 1 u8
- Record type (value: 1).
- 3 byte
- Magic value (“gpg”)
- 1 u8
- TrustDB version (value: 2).
- 1 u8
marginals. How many marginal trusted keys are required.- 1 u8
completes. How many completely trusted keys are required.- 1 u8
max_cert_depth. How deep is the WoT evaluated. Along withmarginalsandcompletes, this value is used to check whether the cached validity value from a [FIXME dir] record can be used.- 1 u8
trust_model- 1 u8
min_cert_level- 2 byte
- Not used
- 1 u32
created. Timestamp of trustdb creation.- 1 u32
nextcheck. 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
reserved. Not used.- 1 u32
reserved2. Not used.- 1 u32
firstfree. Number of the record with the head record of the RECTYPE_FREE linked list.- 1 u32
reserved3. Not used.- 1 u32
trusthashtbl. Record number of the trusthashtable.
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. What we use is a dynamic multilevel architecture, which combines hash tables, record lists, and linked lists.
This record is a hash table of 256 entries with the property 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).
- 1 u8
- Record type (value: 10).
- 1 u8
- Reserved
- n u32
recnum. A table with the hash table items fitting into this record.ndepends on the record length: $n=(reclen-2)/4$ which yields 9 for oure current record length of 40 bytes.
The total number of hash table records to form the table is:
To look up a key we use the first byte of the fingerprint to get the recnum from this hash table and then look up the addressed record:
- If that record is another hash table, we use 2nd byte to index that hash table and so on;
- if that record is a hash list, we walk all entries until we find a matching one; or
- if that record is a key record, we compare the fingerprint to decide whether it is the requested key;
See hash table above on how it is used. It may also be used for other purposes.
- 1 u8
- Record type (value: 11).
- 1 u8
- Reserved.
- 1 u32
next. Record number of the next hash list record or 0 if none.- n u32
rnum. Array with record numbers to values. With $n=(reclen-5)/5$ and our record length of 40, n is 7.
- 1 u8
- Record type (value: 12).
- 1 u8
- Reserved.
- 20 byte
fingerprint.- 1 u8
ownertrust.- 1 u8
depth.- 1 u8
min_ownertrust.- 1 byte
- Not used.
- 1 u32
validlist.- 10 byte
- Not used.
- 1 u8
- Record type (value: 13).
- 1 u8
- Reserved.
- 20 byte
namehash.- 1 u8
validity- 1 u32
next.- 1 u8
full_count.- 1 u8
marginal_count.- 11 byte
- Not used.
All these records form a linked list of unused records in the TrustDB.
- 1 u8
- Record type (value: 254)
- 1 u8
- Reserved.
- 1 u32
next. Record number of the next rcord of this type. The record number to the head of this linked list is stored in the version info record.
1 octet - S2K Usage: either 254 or 255. 1 octet - S2K Cipher Algo: 0 1 octet - S2K Specifier: 101 3 octets - “GNU” 1 octet - GNU S2K Extension Number.
If such a GNU extension is used neither an IV nor any kind of checksum is used. The defined GNU S2K Extension Numbers are:
- 1
- Do not store the secret part at all. No specific data follows.
- 2
- A stub to access smartcards. This data follows:
- One octet with the length of the following serial number.
- The serial number. Regardless of what the length octet indicates no more than 16 octets are stored.
Note that gpg stores the GNU S2K Extension Number internally as an S2K Specifier with an offset of 1000.
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:
- 1xx
- Informational - Request received, continuing process
- 2xx
- Success - The action was successfully received, understood, and accepted
- 4xx
- Client Error - The request contains bad syntax or cannot be fulfilled
- 5xx
- Server Error - The server failed to fulfill an apparently valid request
OIDs below the GnuPG arc:
1.3.6.1.4.1.11591.2 GnuPG 1.3.6.1.4.1.11591.2.1 notation 1.3.6.1.4.1.11591.2.1.1 pkaAddress 1.3.6.1.4.1.11591.2.2 X.509 extensions 1.3.6.1.4.1.11591.2.2.1 standaloneCertificate 1.3.6.1.4.1.11591.2.2.2 wellKnownPrivateKey 1.3.6.1.4.1.11591.2.12242973 invalid encoded OID
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.
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.
When using a –command-fd controlled key generation or “addkey” there is way to know the number to enter on the “keygen.algo” prompt. The displayed numbers are for human reception and may change with releases. To provide a stable way to enter a desired algorithm choice the prompt also accepts predefined names for the algorithms, which will not change.
| Name | No | Description |
|---|---|---|
| rsa+rsa | 1 | RSA and RSA (default) |
| dsa+elg | 2 | DSA and Elgamal |
| dsa | 3 | DSA (sign only) |
| rsa/s | 4 | RSA (sign only) |
| elg | 5 | Elgamal (encrypt only) |
| rsa/e | 6 | RSA (encrypt only) |
| dsa/* | 7 | DSA (set your own capabilities) |
| rsa/* | 8 | RSA (set your own capabilities) |
| ecc+ecc | 9 | ECC and ECC |
| ecc/s | 10 | ECC (sign only) |
| ecc/* | 11 | ECC (set your own capabilities) |
| ecc/e | 12 | ECC (encrypt only) |
| keygrip | 13 | Existing key |
If one of the “foo/*” names are used a “keygen.flags” prompt needs to be answered as well. Instead of toggling the predefined flags, it is also possible to set them direct: Use a “=” character directly followed by a comination of “a” (for authentication), “s” (for signing), or “c” (for certification).