static void mac_setup_by_alg(Mac *mac, const struct macalg *macalg) { mac->type = macalg->type; if (mac->type == SSH_DIGEST) { if ((mac->hmac_ctx = ssh_hmac_start(macalg->alg)) == NULL) fatal("ssh_hmac_start(alg=%d) failed", macalg->alg); mac->key_len = mac->mac_len = ssh_hmac_bytes(macalg->alg); } else { mac->mac_len = macalg->len / 8; mac->key_len = macalg->key_len / 8; mac->umac_ctx = NULL; } if (macalg->truncatebits != 0) mac->mac_len = macalg->truncatebits / 8; mac->etm = macalg->etm; }
/* cc -DTEST hmac.c digest.c buffer.c cleanup.c fatal.c log.c xmalloc.c -lcrypto */ static void hmac_test(void *key, size_t klen, void *m, size_t mlen, u_char *e, size_t elen) { struct ssh_hmac_ctx *ctx; size_t i; u_char digest[16]; if ((ctx = ssh_hmac_start(SSH_DIGEST_MD5)) == NULL) printf("ssh_hmac_start failed"); if (ssh_hmac_init(ctx, key, klen) < 0 || ssh_hmac_update(ctx, m, mlen) < 0 || ssh_hmac_final(ctx, digest, sizeof(digest)) < 0) printf("ssh_hmac_xxx failed"); ssh_hmac_free(ctx); if (memcmp(e, digest, elen)) { for (i = 0; i < elen; i++) printf("[%zd] %2.2x %2.2x\n", i, e[i], digest[i]); printf("mismatch\n"); } else printf("ok\n"); }
char * host_hash(const char *host, const char *name_from_hostfile, u_int src_len) { struct ssh_hmac_ctx *ctx; u_char salt[256], result[256]; char uu_salt[512], uu_result[512]; static char encoded[1024]; u_int i, len; len = ssh_digest_bytes(SSH_DIGEST_SHA1); if (name_from_hostfile == NULL) { /* Create new salt */ for (i = 0; i < len; i++) salt[i] = arc4random(); } else { /* Extract salt from known host entry */ if (extract_salt(name_from_hostfile, src_len, salt, sizeof(salt)) == -1) return (NULL); } if ((ctx = ssh_hmac_start(SSH_DIGEST_SHA1)) == NULL || ssh_hmac_init(ctx, salt, len) < 0 || ssh_hmac_update(ctx, host, strlen(host)) < 0 || ssh_hmac_final(ctx, result, sizeof(result))) fatal("%s: ssh_hmac failed", __func__); ssh_hmac_free(ctx); if (__b64_ntop(salt, len, uu_salt, sizeof(uu_salt)) == -1 || __b64_ntop(result, len, uu_result, sizeof(uu_result)) == -1) fatal("%s: __b64_ntop failed", __func__); snprintf(encoded, sizeof(encoded), "%s%s%c%s", HASH_MAGIC, uu_salt, HASH_DELIM, uu_result); return (encoded); }