commit b9010c8bf5f1231c51cd3c7b134ec8576a8f9de5 Author: George Kadianakis desnacked@riseup.net Date: Mon Sep 5 17:21:44 2016 +0200
prop224 prepwork: Introduce HMAC-SHA3 function. --- src/common/crypto.c | 22 ++++++++++++++++++++++ src/common/crypto.h | 3 +++ src/test/test_crypto.c | 43 +++++++++++++++++++++++++++++++++++++++++++ 3 files changed, 68 insertions(+)
diff --git a/src/common/crypto.c b/src/common/crypto.c index fff516c..e4ef52d 100644 --- a/src/common/crypto.c +++ b/src/common/crypto.c @@ -2109,6 +2109,28 @@ crypto_hmac_sha256(char *hmac_out, tor_assert(rv); }
+/** Compute an SHA3 MAC of <b>msg</b> using <b>key</b> as the key. The format + * used for our MAC is SHA3(k | m). Write the DIGEST256_LEN-byte result into + * <b>mac_out</b> of size <b>mac_out_len</b>. */ +void +crypto_mac_sha3_256(char *mac_out, size_t mac_out_len, + const char *key, size_t key_len, + const char *msg, size_t msg_len) +{ + crypto_digest_t *digest; + + tor_assert(mac_out); + tor_assert(key); + tor_assert(msg); + + digest = crypto_digest256_new(DIGEST_SHA3_256); + + crypto_digest_add_bytes(digest, key, key_len); + crypto_digest_add_bytes(digest, msg, msg_len); + crypto_digest_get_digest(digest, mac_out, mac_out_len); + crypto_digest_free(digest); +} + /** Internal state for a eXtendable-Output Function (XOF). */ struct crypto_xof_t { keccak_state s; diff --git a/src/common/crypto.h b/src/common/crypto.h index 116e0a6..32b6531 100644 --- a/src/common/crypto.h +++ b/src/common/crypto.h @@ -255,6 +255,9 @@ void crypto_digest_assign(crypto_digest_t *into, void crypto_hmac_sha256(char *hmac_out, const char *key, size_t key_len, const char *msg, size_t msg_len); +void crypto_mac_sha3_256(char *mac_out, size_t mac_out_len, + const char *key, size_t key_len, + const char *msg, size_t msg_len); crypto_xof_t *crypto_xof_new(void); void crypto_xof_add_bytes(crypto_xof_t *xof, const uint8_t *data, size_t len); void crypto_xof_squeeze_bytes(crypto_xof_t *xof, uint8_t *out, size_t len); diff --git a/src/test/test_crypto.c b/src/test/test_crypto.c index 64a46f7..91c55d8 100644 --- a/src/test/test_crypto.c +++ b/src/test/test_crypto.c @@ -1135,6 +1135,48 @@ test_crypto_sha3_xof(void *arg) tor_free(mem_op_hex_tmp); }
+/* Test our MAC-SHA3 function. There are not actually any MAC-SHA3 test + * vectors out there for our H(len(k) || k || m) construction. Hence what we + * are gonna do is test our crypto_mac_sha3_256() function against manually + * doing H(len(k) || k||m). If in the future the Keccak group decides to + * standarize an MAC construction and make test vectors, we should + * incorporate them here. */ +static void +test_crypto_mac_sha3(void *arg) +{ + const char msg[] = "i am in a library somewhere using my computer"; + const char key[] = "i'm from the past talking to the future."; + + char hmac_test[DIGEST256_LEN]; + char hmac_manual[DIGEST256_LEN]; + + (void) arg; + + /* First let's use our nice HMAC-SHA3 function */ + crypto_mac_sha3_256(hmac_test, sizeof(hmac_test), + key, strlen(key), + msg, strlen(msg)); + + /* Now let's try a manual H(k || m) construction */ + { + char *key_msg_concat = NULL; + int result; + + tor_asprintf(&key_msg_concat, "%s%s", key, msg); + + result = crypto_digest256(hmac_manual, + key_msg_concat, strlen(key_msg_concat), + DIGEST_SHA3_256); + tt_int_op(result, ==, 0); + tor_free(key_msg_concat); + } + + /* Now compare the two results */ + tt_mem_op(hmac_test, OP_EQ, hmac_manual, DIGEST256_LEN); + + done: ; +} + /** Run unit tests for our public key crypto functions */ static void test_crypto_pk(void *arg) @@ -2918,6 +2960,7 @@ struct testcase_t crypto_tests[] = { { "digest_names", test_crypto_digest_names, 0, NULL, NULL }, { "sha3", test_crypto_sha3, TT_FORK, NULL, NULL}, { "sha3_xof", test_crypto_sha3_xof, TT_FORK, NULL, NULL}, + { "mac_sha3", test_crypto_mac_sha3, TT_FORK, NULL, NULL}, CRYPTO_LEGACY(dh), { "aes_iv_AES", test_crypto_aes_iv, TT_FORK, &passthrough_setup, (void*)"aes" },