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# doc/DETAILS -*- org -*-
#+TITLE: GnuPG Details
# Globally disable superscripts and subscripts:
#+OPTIONS: ^:{}
#
# Note: This file uses org-mode; it should be easy to read as plain
# text but be aware of some markup peculiarities: Verbatim code is
# enclosed in #+begin-example, #+end-example blocks or marked by a
# colon as the first non-white-space character, words bracketed with
# equal signs indicate a monospace font, and the usual /italics/,
# *bold*, and _underline_ conventions are recognized.
This is the DETAILS file for GnuPG which specifies some internals and
parts of the external API for GPG and GPGSM.
* Format of the colon listings
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:
#+begin_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:
#+end_example
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.
** Description of the fields
*** Field 1 - 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 [*]
- grp :: Keygrip
- rvk :: Revocation key
- tru :: Trust database information [*]
- spk :: Signature subpacket [*]
- cfg :: Configuration data [*]
Records marked with an asterisk are described at [[*Special%20field%20formats][*Special fields]].
*** Field 2 - Validity
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.
*** Field 3 - Key length
The length of key in bits.
*** Field 4 - Public key algorithm
The values here are those from the OpenPGP specs or if they are
greather than 255 the algorithm ids as used by Libgcrypt.
*** Field 5 - KeyID
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.
*** Field 6 - Creation date
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.
*** Field 7 - Expiration date
Key or UID/UAT expiration date or empty if it does not expire.
*** Field 8 - Certificate S/N, UID hash, trust signature info
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.
*** Field 9 - Ownertrust
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.
*** Field 10 - User-ID
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.
*** Field 11 - Signature class
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.
*** Field 12 - Key capabilities
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.
*** Field 13 - Issuer certificate fingerprint or other info
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.
*** Field 14 - Flag field
Flag field used in the --edit menu output
*** Field 15 - S/N of a token
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.
*** Field 16 - Hash algorithm
For sig records, this is the used hash algorithm. For example:
2 = SHA-1, 8 = SHA-256.
*** Field 17 - Curve name
For pub, sub, sec, and ssb records this field is used for the ECC
curve name.
** Special fields
*** PKD - Public key data
If field 1 has the tag "pkd", a listing looks like this:
#+begin_example
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)
#+end_example
*** TRU - Trust database information
Example for a "tru" trust base record:
#+begin_example
tru:o:0:1166697654:1:3:1:5
#+end_example
- 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)
*** SPK - Signature subpacket records
- 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.
*** CFG - Configuration data
--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 =pubkeyname= prints 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 =ciphername= prints 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 =digestname= prints 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 patti
would 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 =curveoid= prints OIDs instead of numbers.
: cfg:curve:ed25519;nistp256;nistp384;nistp521
* Format of the --status-fd output
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.
** General status codes
*** NEWSIG
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.
*** GOODSIG <long_keyid_or_fpr> <username>
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.
*** EXPSIG <long_keyid_or_fpr> <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. 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.
*** EXPKEYSIG <long_keyid_or_fpr> <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. 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.
*** REVKEYSIG <long_keyid_or_fpr> <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. 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.
*** BADSIG <long_keyid_or_fpr> <username>
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.
*** ERRSIG <keyid> <pkalgo> <hashalgo> <sig_class> <time> <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. 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'.
*** VALIDSIG <args>
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 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.
The primary-key-fpr parameter is used for OpenPGP and not
class is not defined for CMS and currently set to 0 and 00.
available for CMS signatures. The sig-version as well as the sig
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'.
*** 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 of seconds since
Epoch or an ISO 8601 string which can be detected by the presence
of the letter 'T'.
*** ENC_TO <long_keyid> <keytype> <keylength>
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.
*** BEGIN_DECRYPTION
Mark the start of the actual decryption process. This is also
emitted when in --list-only mode.
*** END_DECRYPTION
Mark the end of the actual decryption process. This are also
emitted when in --list-only mode.
*** DECRYPTION_INFO <mdc_method> <sym_algo>
Print information about the symmetric encryption algorithm and the
MDC method. This will be emitted even if the decryption fails.
*** 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.
*** SESSION_KEY <algo>:<hexdigits>
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.
*** BEGIN_ENCRYPTION <mdc_method> <sym_algo>
Mark the start of the actual encryption process.
*** END_ENCRYPTION
Mark the end of the actual encryption process.
*** 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_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.
*** ALREADY_SIGNED <long-keyid>
Warning: This is experimental and might be removed at any time.
*** SIG_CREATED <type> <pk_algo> <hash_algo> <class> <timestamp> <keyfpr>
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'.
*** NOTATION_
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.
*** POLICY_URL <string>
Note that URL in <string> is %XX escaped.
*** 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.
*** ATTRIBUTE <arguments>
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
*** SIG_SUBPACKET <type> <flags> <len> <data>
This indicates that a signature subpacket was seen. The format is
the same as the "spk" record above.
** Key related
*** INV_RECP, INV_SGNR
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.
*** NO_RECP <reserved>
Issued if no recipients are usable.
*** NO_SGNR <reserved>
Issued if no senders are usable.
*** KEYEXPIRED <expire-timestamp>
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'.
*** KEYREVOKED
The used key has been revoked by its owner. No arguments yet.
*** NO_PUBKEY <long keyid>
The public key is not available
*** NO_SECKEY <long keyid>
The secret key is not available
*** KEY_CREATED <type> <fingerprint> [<handle>]
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.
*** KEY_NOT_CREATED [<handle>]
The key from batch run has not been created due to errors.
*** TRUST_
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.
*** PKA_TRUST_
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.
** Remote control
*** GET_BOOL, GET_LINE, GET_HIDDEN, GOT_IT
These status line are used with --command-fd for interactive
control of the process.
*** USERID_HINT <long main keyid> <string>
Give a hint about the user ID for a certain keyID.
*** NEED_PASSPHRASE <long keyid> <long main 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.
** Import/Export
*** 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 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.
*** 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 <args>
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>
** Smartcard related
*** 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. 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
*** 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.
** Miscellaneous status codes
*** 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. Codes for WHAT are:
- 0 :: Not further specified
- 1 :: Corrupted message structure
*** TRUNCATED <maxno>
The output was truncated to MAXNO items. This status code is
issued for certain external requests.
*** ERROR <error location> <error code> [<more>]
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".
*** SUCCESS [<location>]
Postive confirimation that an operation succeeded. <location> is
optional but if given should not contain spaces. Used only with a
few commands.
*** BADARMOR
The ASCII armor is corrupted. No arguments yet.
*** DELETE_PROBLEM <reason_code>
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.
*** 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. 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
*** BACKUP_KEY_CREATED <fingerprint> <fname>
A backup of a key identified by <fingerprint> has been writte to
the file <fname>; <fname> is percent-escaped.
*** MOUNTPOINT <name>
<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.
*** PINENTRY_LAUNCHED <pid>
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
** Obsolete status codes
*** SIGEXPIRED
Removed on 2011-02-04. This is deprecated in favor of KEYEXPIRED.
*** RSA_OR_IDEA
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.
*** BEGIN_STREAM, END_STREAM
Used to issued by the experimental pipemode.
* 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 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.
* Unattended key generation
Please see the GnuPG manual for a description.
* 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.
#+begin_example
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
#+end_example
* GNU extensions to the S2K algorithm
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.
* Keyserver helper message format
The keyserver may be contacted by a Unix Domain socket or via TCP.
The format of a request is:
#+begin_example
command-tag
"Content-length:" digits
CRLF
#+end_example
Where command-tag is
#+begin_example
NOOP
GET <user-name>
PUT
DELETE <user-name>
#+end_example
The format of a response is:
#+begin_example
"GNUPG/1.0" status-code status-text
"Content-length:" digits
CRLF
#+end_example
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
* Object identifiers
OIDs below the GnuPG arc:
#+begin_example
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
#+end_example
* Miscellaneous notes
** v3 fingerprints
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.
** Simplified revocation certificates
Revocation certificates consist only of the signature packet;
"--import" knows how to handle this. The rationale behind it is to
keep them small.
** 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.
** Algorithm names for the "keygen.algo" prompt
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).
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