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* 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.
Layout of the TrustDB
=====================
FIXME: use a directory record as top node instead of the pubkey record
The TrustDB is build from fixed length records, where the first bytes
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.
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 onyl one with type 1.
1 byte value 1
3 bytes 'g10' magic value
1 byte Version of the TrustDB
3 byte reserved
1 u32 locked by (pid) 0 = not locked.
1 u32 timestamp of trustdb creation
1 u32 timestamp of last modification
1 u32 timestamp of last validation
(Used to keep track of the time, when this TrustDB was checked
against the pubring)
1 u32 Local-Id-Counter. Used to keep track of Local-IDs.
32 bits are enough numbers for all practial purposes; if this
counter rolls over (due to deleted keyblock and new ones),
the software should reassign new Local-Ids to the whole
database (not expected to ever occur).
1 byte marginals needed
1 byte completes needed
1 byte max. cert depth
If any of this 3 values are changed, all cache records
muts be invalidated.
9 bytes reserved
Record type 2:
--------------
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 Local-Id. This is used to bind all records for
a given certificate together. It is valid only in this TrustDB
and usefull if we have duplicate keyids
It is not defined, how an implementaion selects such
a Local-Id, but it may use the local-ID counter from
record type 1, or simply use the offset of Record type 2
8 bytes keyid (of the primary key)
1 byte pubkey algorithm
1 byte reserved
20 bytes fingerprint of the public key
1 byte ownertrust:
Bits 2-0:
0 = undefined (not yet initialized)
1 = unknown owner (could not initialize it)
2 = do not trust this owner
4 = usually trust this owner
5 = always trust this owner
7 = ultimately trust this owner. This can only be set if
we have control over the secret key too.
Bit 3: set if key is revoked; do not use it.
Bit 7-4: reserved
1 byte No signatures (used to avoid duplicate building).
FIXME: this should be moved to the cahce record
2 byte reserved
Record type 3: (cache record)
--------------
Used to bind the trustDB to the concrete instance of keyblock in
a pubring. This is used to cache informations.
1 byte value 3
1 byte reserved
1 u32 Local-Id.
8 bytes keyid of the primary key (needed?)
1 byte cache-is-valid the following stuff is only
valid if this is set.
1 byte reserved
20 bytes rmd160 hash value over the complete keyblock
This is used to detect any changes of the keyblock with all
CTBs and lengths headers. Calculation is easy if the keyblock
is optained from a keyserved: simply create the hash from all
received data bytes.
1 byte number of untrusted signatures.
1 byte number of marginal trusted signatures.
1 byte number of fully trusted signatures.
(255 is stored for all values greater than 254)
1 byte Trustlevel
0 = undefined (not calculated)
1 = unknown
2 = not trusted
3 = marginally trusted
4 = fully trusted
5 = ultimately trusted (have secret key too).
Record type 4 (sigrec)
-------------
Used to keep track of valid key signatures. Self-signatures are not
stored.
1 byte value 4
1 byte reserved
1 u32 Local-Id of owners (pubkey record)
1 u32 chain: next sigrec of this owner or 0 to indicate the
last sigrec.
6 times
1 u32 Local_id of signators pubkey record
1 byte reserved
Record type 5 (next-sigrec)
-------------
This is the same as record type 4 but the record type is 5 and the
local-id is only used to verify the internal db structure. You can
not search for such a record; access is done based on the chain field
in segrec or netx-sigrec. This is, so that we can handle sigrecords
more easier - there is no need to handle multiple sigrecs when searching
for such a record.
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