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Code Activity

kbx: Redefine the UBID which is now the primary fingerprint.

Browse source 
* common/util.h (UBID_LEN): New.  Use it at all places.
* kbx/keybox-blob.c (create_blob_finish): Do not write the UBID item.
* kbx/keybox-dump.c (print_ubib): Remove.
(_keybox_dump_blob): Do not print the now removed ubid flag.
* kbx/keybox-search-desc.h (struct keydb_search_desc): Use constants
for the size of the ubid and grip.
* kbx/keybox-search.c (blob_cmp_ubid): New.
(has_ubid): Make it a simple wrapper around blob_cmp_ubid.
(keybox_get_data): Add arg 'r_ubid'.

* kbx/frontend.h (enum kbxd_store_modes): New.
* kbx/kbxserver.c (cmd_store): Add new option --insert.

* kbx/backend-cache.c (be_cache_initialize): New.
(be_cache_add_resource): Call it here.
* kbx/backend-kbx.c (be_kbx_seek): Remove args 'fpr' and 'fprlen'.
(be_kbx_search): Get the UBID from keybox_get_data.
* kbx/backend-support.c (be_fingerprint_from_blob): Replace by ...
(be_ubid_from_blob): new.  Change all callers.

* kbx/frontend.c (kbxd_add_resource): Temporary disable the cache but
use the new cache init function.
(kbxd_store): Replace arg 'only_update' by 'mode'.  Seek using the
ubid.  Take care of the mode.
--

It turned out that using the hash of the entire blob was not helpful.
Thus we redefine the Unique-Blob-ID (UBID) as the primary fingerprint
of the blob.  In case this is a v5 OpenPGP key a left truncated
version of the SHA-256 hash is used; in all other cases the full SHA-1
hash.  Using a SHA-256 hash does not make sense because v4 keys are
and will for some time be the majority of keys and thus padding them
with zeroes won't make any difference.  Even if fingerprint collisions
can eventually be created we will assume that the keys are bogus and
that it does not make sense to store its twin also in our key storage.
We can also easily extend the update code to detect a collision and
reject the update.

Signed-off-by: Werner Koch <wk@gnupg.org>
This commit is contained in:
Werner Koch 2019-11-28 09:39:35 +01:00
parent f59455d054
commit 915297705a
No known key found for this signature in database
GPG key ID: E3FDFF218E45B72B
18 changed files with 170 additions and 180 deletions
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48
kbx/keybox-dump.c
View file

@ -63,41 +63,6 @@ print_string (FILE *fp, const byte *p, size_t n, int delim)
}
static void
print_ubib (const byte *buffer, size_t length, FILE *fp)
{
const byte *p;
int i;
size_t image_off, image_len;
unsigned char digest[20];
fprintf (fp, "UBIB: ");
if (length < 40)
{
fputs ("[blob too short for a stored UBIB]\n", fp);
return;
}
p = buffer + length - 40;
for (i=0; i < 20; p++, i++)
fprintf (fp, "%02X", *p);
image_off = get32 (buffer+8);
image_len = get32 (buffer+12);
if ((uint64_t)image_off+(uint64_t)image_len > (uint64_t)length)
{
fputs (" [image claims to be longer than the blob]\n", fp);
return;
}
gcry_md_hash_buffer (GCRY_MD_SHA1, digest, buffer+image_off,image_len);
if (memcmp (digest, buffer + length - 40, 20))
fputs (" [does not match the image]\n", fp);
else
fputc ('\n', fp);
}
static int
print_checksum (const byte *buffer, size_t length, size_t unhashed, FILE *fp)
{
@ -205,8 +170,7 @@ _keybox_dump_blob (KEYBOXBLOB blob, FILE *fp)
ulong nserial;
ulong unhashed;
const byte *p;
int is_fpr32; /* blob ersion 2 */
int have_ubib = 0;
int is_fpr32; /* blob version 2 */
buffer = _keybox_get_blob_image (blob, &length);
@ -273,14 +237,6 @@ _keybox_dump_blob (KEYBOXBLOB blob, FILE *fp)
fputs ("ephemeral", fp);
any++;
}
if ((n & 4))
{
if (any)
putc (',', fp);
fputs ("ubid", fp);
any++;
have_ubib = 1;
}
putc (')', fp);
}
putc ('\n', fp);
@ -466,8 +422,6 @@ _keybox_dump_blob (KEYBOXBLOB blob, FILE *fp)
n = get32 ( buffer + length - unhashed);
fprintf (fp, "Storage-Flags: %08lx\n", n );
}
if (have_ubib)
print_ubib (buffer, length, fp);
print_checksum (buffer, length, unhashed, fp);
return 0;
}