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

* 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>

1 files changed, 8 insertions, 20 deletions

diff --git a/kbx/backend-kbx.c b/kbx/backend-kbx.c
index d8dafe0e5..ff4f56773 100644
--- a/kbx/backend-kbx.c
+++ b/kbx/backend-kbx.c
@@ -271,15 +271,15 @@ be_kbx_search (ctrl_t ctrl, backend_handle_t backend_hd, db_request_t request,
       void *buffer;
       size_t buflen;
       enum pubkey_types pubkey_type;
-      unsigned char blobid[20];
+      unsigned char ubid[UBID_LEN];
 
-      err = keybox_get_data (part->kbx_hd, &buffer, &buflen, &pubkey_type);
+      err = keybox_get_data (part->kbx_hd, &buffer, &buflen,
+                             &pubkey_type, ubid);
       if (err)
         goto leave;
-      gcry_md_hash_buffer (GCRY_MD_SHA1, blobid, buffer, buflen);
-      err = be_return_pubkey (ctrl, buffer, buflen, pubkey_type, blobid);
+      err = be_return_pubkey (ctrl, buffer, buflen, pubkey_type, ubid);
       if (!err)
-        be_cache_pubkey (ctrl, blobid, buffer, buflen, pubkey_type);
+        be_cache_pubkey (ctrl, ubid, buffer, buflen, pubkey_type);
       xfree (buffer);
     }
 
@@ -295,8 +295,7 @@ be_kbx_search (ctrl_t ctrl, backend_handle_t backend_hd, db_request_t request,
  * operation starts right after that UBID. */
 gpg_error_t
 be_kbx_seek (ctrl_t ctrl, backend_handle_t backend_hd,
-             db_request_t request, const unsigned char *ubid,
-             const unsigned char *fpr, unsigned int fprlen)
+             db_request_t request, const unsigned char *ubid)
 {
   gpg_error_t err;
   db_request_part_t part;
@@ -310,19 +309,8 @@ be_kbx_seek (ctrl_t ctrl, backend_handle_t backend_hd,
   log_assert (request);
 
   memset (&desc, 0, sizeof desc);
-  if (ubid)
-    {
-      desc.mode = KEYDB_SEARCH_MODE_FPR;
-      memcpy (desc.u.ubid, ubid, 20);
-    }
-  else
-    {
-      if (fprlen > sizeof desc.u.fpr)
-        return gpg_error (GPG_ERR_TOO_LARGE);
-      desc.mode = KEYDB_SEARCH_MODE_FPR;
-      memcpy (desc.u.fpr, fpr, fprlen);
-      desc.fprlen = fprlen;
-    }
+  desc.mode = KEYDB_SEARCH_MODE_UBID;
+  memcpy (desc.u.ubid, ubid, UBID_LEN);
 
   /* Find the specific request part or allocate it.  */
   err = be_find_request_part (backend_hd, request, &part);