Add support for calculating SKS style key hashes

  SKS uses an MD5 hash over the sorted packets from a key as a token
  for its gossip protocol. Add support for calculating this hash and a
  structure for passing it around within onak.

diff --git a/keyid.c b/keyid.c
index 2bec710026f85a92fe4ce6f8547700d6b998f3c1..0516f477e028eac7d7fb584be15a90259c106dfb 100644 (file)
--- a/keyid.c
+++ b/keyid.c
@@ -7,11 +7,15 @@
  */
 
 #include <sys/types.h>
+#include <arpa/inet.h>
 
 #include "keyid.h"
 #include "keystructs.h"
 #include "log.h"
+#include "parsekey.h"
 #include "md5.h"
+#include "mem.h"
+#include "merge.h"
 #include "sha1.h"
 
 
@@ -156,3 +160,59 @@ uint64_t get_packetid(struct openpgp_packet *packet)
 
        return keyid;
 }
+
+static struct openpgp_packet_list *sortpackets(struct openpgp_packet_list
+                                                       *packets)
+{
+       struct openpgp_packet_list *sorted, **cur, *next;
+
+       sorted = NULL;
+       while (packets != NULL) {
+               cur = &sorted;
+               while (*cur != NULL && compare_packets((*cur)->packet,
+                               packets->packet) < 0) {
+                       cur = &((*cur)->next);
+               }
+               next = *cur;
+               *cur = packets;
+               packets = packets->next;
+               (*cur)->next = next;
+       }
+
+       return sorted;
+}
+
+void get_skshash(struct openpgp_publickey *key, struct skshash *hash)
+{
+       struct openpgp_packet_list *packets = NULL, *list_end = NULL;
+       struct openpgp_packet_list *curpacket;
+       struct md5_ctx md5_context;
+       struct openpgp_publickey *next;
+       uint32_t tmp;
+
+       /*
+        * We only want a single key, so clear any link to the next
+        * one for the period during the flatten.
+        */
+       next = key->next;
+       key->next = NULL;
+       flatten_publickey(key, &packets, &list_end);
+       key->next = next;
+       packets = sortpackets(packets);
+
+       md5_init_ctx(&md5_context);
+
+       for (curpacket = packets; curpacket != NULL;
+                       curpacket = curpacket->next) {
+               tmp = htonl(curpacket->packet->tag);
+               md5_process_bytes(&tmp, sizeof(tmp), &md5_context);
+               tmp = htonl(curpacket->packet->length);
+               md5_process_bytes(&tmp, sizeof(tmp), &md5_context);
+               md5_process_bytes(curpacket->packet->data,
+                               curpacket->packet->length,
+                               &md5_context);
+       }
+
+       md5_finish_ctx(&md5_context, &hash->hash);
+       free_packet_list(packets);
+}

diff --git a/keyid.h b/keyid.h
index 61ff6b808050e6cab3880f09b1f51822916ac101..202a4a053d019b7960e45d3ecc2d003bff36df5f 100644 (file)
--- a/keyid.h
+++ b/keyid.h
@@ -43,4 +43,16 @@ unsigned char *get_fingerprint(struct openpgp_packet *packet,
  */
 uint64_t get_packetid(struct openpgp_packet *packet);
 
+/**
+ *     get_skshash - Given a public key returns the SKS hash for it.
+ *     @publickey: The key to calculate the hash for.
+ *     @skshash: Hash structure to sort the result in.
+ *
+ *     This function returns the SKS hash for a given public key. This
+ *     is an MD5 hash over a sorted list of all of the packets that
+ *     make up the key. The caller should allocate the memory for the
+ *     hash.
+ */
+void get_skshash(struct openpgp_publickey *publickey, struct skshash *hash);
+
 #endif /* __KEYID_H__ */

diff --git a/keystructs.h b/keystructs.h
index 33c6226ed77cf925544c2af78ef763580a6a0b7b..c77e346e419e6ce139b54fa5993ad936ac15aecb 100644 (file)
--- a/keystructs.h
+++ b/keystructs.h
@@ -104,4 +104,12 @@ struct stats_key {
        bool revoked;
 };
 
+/**
+ *     struct skshash - holds an SKS key hash (md5 over sorted packet list)
+ *     @hash: The 128 bit MD5 hash of the sorted packet list from the key
+ */
+struct skshash {
+       uint8_t hash[16];
+};
+
 #endif /* __KEYSTRUCTS_H__ */