From: Jonathan McDowell Date: Mon, 25 Apr 2011 02:06:06 +0000 (-0700) Subject: Add support for calculating SKS style key hashes X-Git-Url: https://git.sommitrealweird.co.uk/onak.git/commitdiff_plain/3cdd1ba5400b97412d8e69fdcf59284b7cde6e28 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 2bec710..0516f47 100644 --- a/keyid.c +++ b/keyid.c @@ -7,11 +7,15 @@ */ #include +#include #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 61ff6b8..202a4a0 100644 --- 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 33c6226..c77e346 100644 --- 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__ */