static int s2n_sslv3_server_finished(struct s2n_connection *conn) { uint8_t prefix[4] = { 0x53, 0x52, 0x56, 0x52 }; struct s2n_hash_state md5, sha1; lte_check(MD5_DIGEST_LENGTH + SHA_DIGEST_LENGTH, sizeof(conn->handshake.server_finished)); GUARD(s2n_hash_copy(&md5, &conn->handshake.md5)); GUARD(s2n_hash_copy(&sha1, &conn->handshake.sha1)); return s2n_sslv3_finished(conn, prefix, &md5, &sha1, conn->handshake.server_finished); }
int s2n_prf_server_finished(struct s2n_connection *conn) { struct s2n_blob master_secret, md5, sha; uint8_t md5_digest[MD5_DIGEST_LENGTH]; uint8_t sha_digest[SHA384_DIGEST_LENGTH]; uint8_t server_finished_label[] = "server finished"; struct s2n_blob server_finished; struct s2n_blob label; if (conn->actual_protocol_version == S2N_SSLv3) { return s2n_sslv3_server_finished(conn); } server_finished.data = conn->handshake.server_finished; server_finished.size = S2N_TLS_FINISHED_LEN; label.data = server_finished_label; label.size = sizeof(server_finished_label) - 1; master_secret.data = conn->secure.master_secret; master_secret.size = sizeof(conn->secure.master_secret); if (conn->actual_protocol_version == S2N_TLS12) { switch(conn->secure.cipher_suite->tls12_prf_alg) { struct s2n_hash_state hash_state; case S2N_HMAC_SHA256: GUARD(s2n_hash_copy(&hash_state, &conn->handshake.sha256)); GUARD(s2n_hash_digest(&hash_state, sha_digest, SHA256_DIGEST_LENGTH)); sha.size = SHA256_DIGEST_LENGTH; break; case S2N_HMAC_SHA384: GUARD(s2n_hash_copy(&hash_state, &conn->handshake.sha384)); GUARD(s2n_hash_digest(&hash_state, sha_digest, SHA384_DIGEST_LENGTH)); sha.size = SHA384_DIGEST_LENGTH; break; default: S2N_ERROR(S2N_ERR_PRF_INVALID_ALGORITHM); } sha.data = sha_digest; return s2n_prf(conn, &master_secret, &label, &sha, NULL, &server_finished); } struct s2n_hash_state md5_state, sha1_state; GUARD(s2n_hash_copy(&md5_state, &conn->handshake.md5)); GUARD(s2n_hash_copy(&sha1_state, &conn->handshake.sha1)); GUARD(s2n_hash_digest(&md5_state, md5_digest, MD5_DIGEST_LENGTH)); GUARD(s2n_hash_digest(&sha1_state, sha_digest, SHA_DIGEST_LENGTH)); md5.data = md5_digest; md5.size = MD5_DIGEST_LENGTH; sha.data = sha_digest; sha.size = SHA_DIGEST_LENGTH; return s2n_prf(conn, &master_secret, &label, &md5, &sha, &server_finished); }
int main(int argc, char **argv) { uint8_t digest_pad[64]; uint8_t output_pad[96]; uint8_t hello[] = "Hello world!\n"; struct s2n_stuffer output; struct s2n_hash_state hash, copy; struct s2n_blob out = {.data = output_pad,.size = sizeof(output_pad) }; BEGIN_TEST(); /* Initialise our output stuffers */ EXPECT_SUCCESS(s2n_stuffer_init(&output, &out)); uint8_t md5_digest_size; GUARD(s2n_hash_digest_size(S2N_HASH_MD5, &md5_digest_size)); EXPECT_EQUAL(md5_digest_size, 16); EXPECT_SUCCESS(s2n_hash_init(&hash, S2N_HASH_MD5)); EXPECT_SUCCESS(s2n_hash_update(&hash, hello, strlen((char *)hello))); EXPECT_SUCCESS(s2n_hash_copy(©, &hash)); EXPECT_SUCCESS(s2n_hash_digest(&hash, digest_pad, MD5_DIGEST_LENGTH)); for (int i = 0; i < 16; i++) { EXPECT_SUCCESS(s2n_stuffer_write_uint8_hex(&output, digest_pad[i])); } /* Reference value from command line md5sum */ EXPECT_EQUAL(memcmp(output_pad, "59ca0efa9f5633cb0371bbc0355478d8", 16 * 2), 0); /* Check the copy */ EXPECT_SUCCESS(s2n_hash_digest(©, digest_pad, MD5_DIGEST_LENGTH)); for (int i = 0; i < 16; i++) { EXPECT_SUCCESS(s2n_stuffer_write_uint8_hex(&output, digest_pad[i])); } /* Reference value from command line md5sum */ EXPECT_EQUAL(memcmp(output_pad, "59ca0efa9f5633cb0371bbc0355478d8", 16 * 2), 0); EXPECT_SUCCESS(s2n_stuffer_init(&output, &out)); uint8_t sha1_digest_size; GUARD(s2n_hash_digest_size(S2N_HASH_SHA1, &sha1_digest_size)); EXPECT_EQUAL(sha1_digest_size, 20); EXPECT_SUCCESS(s2n_hash_init(&hash, S2N_HASH_SHA1)); EXPECT_SUCCESS(s2n_hash_update(&hash, hello, strlen((char *)hello))); EXPECT_SUCCESS(s2n_hash_digest(&hash, digest_pad, SHA_DIGEST_LENGTH)); for (int i = 0; i < 20; i++) { EXPECT_SUCCESS(s2n_stuffer_write_uint8_hex(&output, digest_pad[i])); } /* Reference value from command line sha1sum */ EXPECT_EQUAL(memcmp(output_pad, "47a013e660d408619d894b20806b1d5086aab03b", 20 * 2), 0); EXPECT_SUCCESS(s2n_stuffer_init(&output, &out)); uint8_t sha256_digest_size; GUARD(s2n_hash_digest_size(S2N_HASH_SHA256, &sha256_digest_size)); EXPECT_EQUAL(sha256_digest_size, 32); EXPECT_SUCCESS(s2n_hash_init(&hash, S2N_HASH_SHA256)); EXPECT_SUCCESS(s2n_hash_update(&hash, hello, strlen((char *)hello))); EXPECT_SUCCESS(s2n_hash_digest(&hash, digest_pad, SHA256_DIGEST_LENGTH)); for (int i = 0; i < 32; i++) { EXPECT_SUCCESS(s2n_stuffer_write_uint8_hex(&output, digest_pad[i])); } /* Reference value from command line sha256sum */ EXPECT_EQUAL(memcmp(output_pad, "0ba904eae8773b70c75333db4de2f3ac45a8ad4ddba1b242f0b3cfc199391dd8", 32 * 2), 0); EXPECT_SUCCESS(s2n_stuffer_init(&output, &out)); uint8_t sha384_digest_size; GUARD(s2n_hash_digest_size(S2N_HASH_SHA384, &sha384_digest_size)); EXPECT_EQUAL(sha384_digest_size, 48); EXPECT_SUCCESS(s2n_hash_init(&hash, S2N_HASH_SHA384)); EXPECT_SUCCESS(s2n_hash_update(&hash, hello, strlen((char *)hello))); EXPECT_SUCCESS(s2n_hash_digest(&hash, digest_pad, SHA384_DIGEST_LENGTH)); for (int i = 0; i < 48; i++) { EXPECT_SUCCESS(s2n_stuffer_write_uint8_hex(&output, digest_pad[i])); } /* Reference value from command line sha512sum */ EXPECT_EQUAL(memcmp(output_pad, "f7f8f1b9d5a9a61742eeda26c20990282ac08dabda14e70376fcb4c8b46198a9959ea9d7d194b38520eed5397ffe6d8e", 48 * 2), 0); END_TEST(); }
static int s2n_prf(struct s2n_connection *conn, struct s2n_blob *secret, struct s2n_blob *label, struct s2n_blob *seed_a, struct s2n_blob *seed_b, struct s2n_blob *seed_c, struct s2n_blob *out) { /* seed_a is always required, seed_b is optional, if seed_c is provided seed_b must also be provided */ S2N_ERROR_IF(seed_a == NULL, S2N_ERR_PRF_INVALID_SEED); S2N_ERROR_IF(seed_b == NULL && seed_c != NULL, S2N_ERR_PRF_INVALID_SEED); if (conn->actual_protocol_version == S2N_SSLv3) { return s2n_sslv3_prf(&conn->prf_space, secret, seed_a, seed_b, seed_c, out); } /* We zero the out blob because p_hash works by XOR'ing with the existing * buffer. This is a little convoluted but means we can avoid dynamic memory * allocation. When we call p_hash once (in the TLS1.2 case) it will produce * the right values. When we call it twice in the regular case, the two * outputs will be XORd just ass the TLS 1.0 and 1.1 RFCs require. */ GUARD(s2n_blob_zero(out)); /* Ensure that p_hash_hmac_impl is set, as it may have been reset for prf_space on s2n_connection_wipe. * When in FIPS mode, the EVP API's must be used for the p_hash HMAC. */ conn->prf_space.tls.p_hash_hmac_impl = s2n_is_in_fips_mode() ? &s2n_evp_hmac : &s2n_hmac; if (conn->actual_protocol_version == S2N_TLS12) { return s2n_p_hash(&conn->prf_space, conn->secure.cipher_suite->tls12_prf_alg, secret, label, seed_a, seed_b, seed_c, out); } struct s2n_blob half_secret = {.data = secret->data,.size = (secret->size + 1) / 2 }; GUARD(s2n_p_hash(&conn->prf_space, S2N_HMAC_MD5, &half_secret, label, seed_a, seed_b, seed_c, out)); half_secret.data += secret->size - half_secret.size; GUARD(s2n_p_hash(&conn->prf_space, S2N_HMAC_SHA1, &half_secret, label, seed_a, seed_b, seed_c, out)); return 0; } int s2n_tls_prf_master_secret(struct s2n_connection *conn, struct s2n_blob *premaster_secret) { struct s2n_blob client_random = {.size = sizeof(conn->secure.client_random), .data = conn->secure.client_random}; struct s2n_blob server_random = {.size = sizeof(conn->secure.server_random), .data = conn->secure.server_random}; struct s2n_blob master_secret = {.size = sizeof(conn->secure.master_secret), .data = conn->secure.master_secret}; uint8_t master_secret_label[] = "master secret"; struct s2n_blob label = {.size = sizeof(master_secret_label) - 1, .data = master_secret_label}; return s2n_prf(conn, premaster_secret, &label, &client_random, &server_random, NULL, &master_secret); } int s2n_hybrid_prf_master_secret(struct s2n_connection *conn, struct s2n_blob *premaster_secret) { struct s2n_blob client_random = {.size = sizeof(conn->secure.client_random), .data = conn->secure.client_random}; struct s2n_blob server_random = {.size = sizeof(conn->secure.server_random), .data = conn->secure.server_random}; struct s2n_blob master_secret = {.size = sizeof(conn->secure.master_secret), .data = conn->secure.master_secret}; uint8_t master_secret_label[] = "hybrid master secret"; struct s2n_blob label = {.size = sizeof(master_secret_label) - 1, .data = master_secret_label}; return s2n_prf(conn, premaster_secret, &label, &client_random, &server_random, &conn->secure.client_key_exchange_message, &master_secret); } static int s2n_sslv3_finished(struct s2n_connection *conn, uint8_t prefix[4], struct s2n_hash_state *md5, struct s2n_hash_state *sha1, uint8_t * out) { uint8_t xorpad1[48] = { 0x36, 0x36, 0x36, 0x36, 0x36, 0x36, 0x36, 0x36, 0x36, 0x36, 0x36, 0x36, 0x36, 0x36, 0x36, 0x36, 0x36, 0x36, 0x36, 0x36, 0x36, 0x36, 0x36, 0x36, 0x36, 0x36, 0x36, 0x36, 0x36, 0x36, 0x36, 0x36, 0x36, 0x36, 0x36, 0x36, 0x36, 0x36, 0x36, 0x36, 0x36, 0x36, 0x36, 0x36, 0x36, 0x36, 0x36, 0x36 }; uint8_t xorpad2[48] = { 0x5c, 0x5c, 0x5c, 0x5c, 0x5c, 0x5c, 0x5c, 0x5c, 0x5c, 0x5c, 0x5c, 0x5c, 0x5c, 0x5c, 0x5c, 0x5c, 0x5c, 0x5c, 0x5c, 0x5c, 0x5c, 0x5c, 0x5c, 0x5c, 0x5c, 0x5c, 0x5c, 0x5c, 0x5c, 0x5c, 0x5c, 0x5c, 0x5c, 0x5c, 0x5c, 0x5c, 0x5c, 0x5c, 0x5c, 0x5c, 0x5c, 0x5c, 0x5c, 0x5c, 0x5c, 0x5c, 0x5c, 0x5c }; uint8_t *md5_digest = out; uint8_t *sha_digest = out + MD5_DIGEST_LENGTH; lte_check(MD5_DIGEST_LENGTH + SHA_DIGEST_LENGTH, sizeof(conn->handshake.client_finished)); GUARD(s2n_hash_update(md5, prefix, 4)); GUARD(s2n_hash_update(md5, conn->secure.master_secret, sizeof(conn->secure.master_secret))); GUARD(s2n_hash_update(md5, xorpad1, 48)); GUARD(s2n_hash_digest(md5, md5_digest, MD5_DIGEST_LENGTH)); GUARD(s2n_hash_reset(md5)); GUARD(s2n_hash_update(md5, conn->secure.master_secret, sizeof(conn->secure.master_secret))); GUARD(s2n_hash_update(md5, xorpad2, 48)); GUARD(s2n_hash_update(md5, md5_digest, MD5_DIGEST_LENGTH)); GUARD(s2n_hash_digest(md5, md5_digest, MD5_DIGEST_LENGTH)); GUARD(s2n_hash_reset(md5)); GUARD(s2n_hash_update(sha1, prefix, 4)); GUARD(s2n_hash_update(sha1, conn->secure.master_secret, sizeof(conn->secure.master_secret))); GUARD(s2n_hash_update(sha1, xorpad1, 40)); GUARD(s2n_hash_digest(sha1, sha_digest, SHA_DIGEST_LENGTH)); GUARD(s2n_hash_reset(sha1)); GUARD(s2n_hash_update(sha1, conn->secure.master_secret, sizeof(conn->secure.master_secret))); GUARD(s2n_hash_update(sha1, xorpad2, 40)); GUARD(s2n_hash_update(sha1, sha_digest, SHA_DIGEST_LENGTH)); GUARD(s2n_hash_digest(sha1, sha_digest, SHA_DIGEST_LENGTH)); GUARD(s2n_hash_reset(sha1)); return 0; } static int s2n_sslv3_client_finished(struct s2n_connection *conn) { uint8_t prefix[4] = { 0x43, 0x4c, 0x4e, 0x54 }; lte_check(MD5_DIGEST_LENGTH + SHA_DIGEST_LENGTH, sizeof(conn->handshake.client_finished)); GUARD(s2n_hash_copy(&conn->handshake.prf_md5_hash_copy, &conn->handshake.md5)); GUARD(s2n_hash_copy(&conn->handshake.prf_sha1_hash_copy, &conn->handshake.sha1)); return s2n_sslv3_finished(conn, prefix, &conn->handshake.prf_md5_hash_copy, &conn->handshake.prf_sha1_hash_copy, conn->handshake.client_finished); } static int s2n_sslv3_server_finished(struct s2n_connection *conn) { uint8_t prefix[4] = { 0x53, 0x52, 0x56, 0x52 }; lte_check(MD5_DIGEST_LENGTH + SHA_DIGEST_LENGTH, sizeof(conn->handshake.server_finished)); GUARD(s2n_hash_copy(&conn->handshake.prf_md5_hash_copy, &conn->handshake.md5)); GUARD(s2n_hash_copy(&conn->handshake.prf_sha1_hash_copy, &conn->handshake.sha1)); return s2n_sslv3_finished(conn, prefix, &conn->handshake.prf_md5_hash_copy, &conn->handshake.prf_sha1_hash_copy, conn->handshake.server_finished); } int s2n_prf_client_finished(struct s2n_connection *conn) { struct s2n_blob master_secret, md5, sha; uint8_t md5_digest[MD5_DIGEST_LENGTH]; uint8_t sha_digest[SHA384_DIGEST_LENGTH]; uint8_t client_finished_label[] = "client finished"; struct s2n_blob client_finished = {0}; struct s2n_blob label = {0}; if (conn->actual_protocol_version == S2N_SSLv3) { return s2n_sslv3_client_finished(conn); } client_finished.data = conn->handshake.client_finished; client_finished.size = S2N_TLS_FINISHED_LEN; label.data = client_finished_label; label.size = sizeof(client_finished_label) - 1; master_secret.data = conn->secure.master_secret; master_secret.size = sizeof(conn->secure.master_secret); if (conn->actual_protocol_version == S2N_TLS12) { switch (conn->secure.cipher_suite->tls12_prf_alg) { case S2N_HMAC_SHA256: GUARD(s2n_hash_copy(&conn->handshake.prf_tls12_hash_copy, &conn->handshake.sha256)); GUARD(s2n_hash_digest(&conn->handshake.prf_tls12_hash_copy, sha_digest, SHA256_DIGEST_LENGTH)); sha.size = SHA256_DIGEST_LENGTH; break; case S2N_HMAC_SHA384: GUARD(s2n_hash_copy(&conn->handshake.prf_tls12_hash_copy, &conn->handshake.sha384)); GUARD(s2n_hash_digest(&conn->handshake.prf_tls12_hash_copy, sha_digest, SHA384_DIGEST_LENGTH)); sha.size = SHA384_DIGEST_LENGTH; break; default: S2N_ERROR(S2N_ERR_PRF_INVALID_ALGORITHM); } sha.data = sha_digest; return s2n_prf(conn, &master_secret, &label, &sha, NULL, NULL, &client_finished); } GUARD(s2n_hash_copy(&conn->handshake.prf_md5_hash_copy, &conn->handshake.md5)); GUARD(s2n_hash_copy(&conn->handshake.prf_sha1_hash_copy, &conn->handshake.sha1)); GUARD(s2n_hash_digest(&conn->handshake.prf_md5_hash_copy, md5_digest, MD5_DIGEST_LENGTH)); GUARD(s2n_hash_digest(&conn->handshake.prf_sha1_hash_copy, sha_digest, SHA_DIGEST_LENGTH)); md5.data = md5_digest; md5.size = MD5_DIGEST_LENGTH; sha.data = sha_digest; sha.size = SHA_DIGEST_LENGTH; return s2n_prf(conn, &master_secret, &label, &md5, &sha, NULL, &client_finished); } int s2n_prf_server_finished(struct s2n_connection *conn) { struct s2n_blob master_secret, md5, sha; uint8_t md5_digest[MD5_DIGEST_LENGTH]; uint8_t sha_digest[SHA384_DIGEST_LENGTH]; uint8_t server_finished_label[] = "server finished"; struct s2n_blob server_finished = {0}; struct s2n_blob label = {0}; if (conn->actual_protocol_version == S2N_SSLv3) { return s2n_sslv3_server_finished(conn); } server_finished.data = conn->handshake.server_finished; server_finished.size = S2N_TLS_FINISHED_LEN; label.data = server_finished_label; label.size = sizeof(server_finished_label) - 1; master_secret.data = conn->secure.master_secret; master_secret.size = sizeof(conn->secure.master_secret); if (conn->actual_protocol_version == S2N_TLS12) { switch (conn->secure.cipher_suite->tls12_prf_alg) { case S2N_HMAC_SHA256: GUARD(s2n_hash_copy(&conn->handshake.prf_tls12_hash_copy, &conn->handshake.sha256)); GUARD(s2n_hash_digest(&conn->handshake.prf_tls12_hash_copy, sha_digest, SHA256_DIGEST_LENGTH)); sha.size = SHA256_DIGEST_LENGTH; break; case S2N_HMAC_SHA384: GUARD(s2n_hash_copy(&conn->handshake.prf_tls12_hash_copy, &conn->handshake.sha384)); GUARD(s2n_hash_digest(&conn->handshake.prf_tls12_hash_copy, sha_digest, SHA384_DIGEST_LENGTH)); sha.size = SHA384_DIGEST_LENGTH; break; default: S2N_ERROR(S2N_ERR_PRF_INVALID_ALGORITHM); } sha.data = sha_digest; return s2n_prf(conn, &master_secret, &label, &sha, NULL, NULL, &server_finished); } GUARD(s2n_hash_copy(&conn->handshake.prf_md5_hash_copy, &conn->handshake.md5)); GUARD(s2n_hash_copy(&conn->handshake.prf_sha1_hash_copy, &conn->handshake.sha1)); GUARD(s2n_hash_digest(&conn->handshake.prf_md5_hash_copy, md5_digest, MD5_DIGEST_LENGTH)); GUARD(s2n_hash_digest(&conn->handshake.prf_sha1_hash_copy, sha_digest, SHA_DIGEST_LENGTH)); md5.data = md5_digest; md5.size = MD5_DIGEST_LENGTH; sha.data = sha_digest; sha.size = SHA_DIGEST_LENGTH; return s2n_prf(conn, &master_secret, &label, &md5, &sha, NULL, &server_finished); } static int s2n_prf_make_client_key(struct s2n_connection *conn, struct s2n_stuffer *key_material) { struct s2n_blob client_key = {0}; client_key.size = conn->secure.cipher_suite->record_alg->cipher->key_material_size; client_key.data = s2n_stuffer_raw_read(key_material, client_key.size); notnull_check(client_key.data); if (conn->mode == S2N_CLIENT) { GUARD(conn->secure.cipher_suite->record_alg->cipher->set_encryption_key(&conn->secure.client_key, &client_key)); } else { GUARD(conn->secure.cipher_suite->record_alg->cipher->set_decryption_key(&conn->secure.client_key, &client_key)); } return 0; } static int s2n_prf_make_server_key(struct s2n_connection *conn, struct s2n_stuffer *key_material) { struct s2n_blob server_key = {0}; server_key.size = conn->secure.cipher_suite->record_alg->cipher->key_material_size; server_key.data = s2n_stuffer_raw_read(key_material, server_key.size); notnull_check(server_key.data); if (conn->mode == S2N_SERVER) { GUARD(conn->secure.cipher_suite->record_alg->cipher->set_encryption_key(&conn->secure.server_key, &server_key)); } else { GUARD(conn->secure.cipher_suite->record_alg->cipher->set_decryption_key(&conn->secure.server_key, &server_key)); } return 0; } int s2n_prf_key_expansion(struct s2n_connection *conn) { struct s2n_blob client_random = {.data = conn->secure.client_random,.size = sizeof(conn->secure.client_random) }; struct s2n_blob server_random = {.data = conn->secure.server_random,.size = sizeof(conn->secure.server_random) }; struct s2n_blob master_secret = {.data = conn->secure.master_secret,.size = sizeof(conn->secure.master_secret) }; struct s2n_blob label, out; uint8_t key_expansion_label[] = "key expansion"; uint8_t key_block[S2N_MAX_KEY_BLOCK_LEN]; label.data = key_expansion_label; label.size = sizeof(key_expansion_label) - 1; out.data = key_block; out.size = sizeof(key_block); struct s2n_stuffer key_material = {{0}}; GUARD(s2n_prf(conn, &master_secret, &label, &server_random, &client_random, NULL, &out)); GUARD(s2n_stuffer_init(&key_material, &out)); GUARD(s2n_stuffer_write(&key_material, &out)); GUARD(conn->secure.cipher_suite->record_alg->cipher->init(&conn->secure.client_key)); GUARD(conn->secure.cipher_suite->record_alg->cipher->init(&conn->secure.server_key)); /* Check that we have a valid MAC and key size */ uint8_t mac_size; if (conn->secure.cipher_suite->record_alg->cipher->type == S2N_COMPOSITE) { mac_size = conn->secure.cipher_suite->record_alg->cipher->io.comp.mac_key_size; } else { GUARD(s2n_hmac_digest_size(conn->secure.cipher_suite->record_alg->hmac_alg, &mac_size)); } /* Seed the client MAC */ uint8_t *client_mac_write_key = s2n_stuffer_raw_read(&key_material, mac_size); notnull_check(client_mac_write_key); GUARD(s2n_hmac_reset(&conn->secure.client_record_mac)); GUARD(s2n_hmac_init(&conn->secure.client_record_mac, conn->secure.cipher_suite->record_alg->hmac_alg, client_mac_write_key, mac_size)); /* Seed the server MAC */ uint8_t *server_mac_write_key = s2n_stuffer_raw_read(&key_material, mac_size); notnull_check(server_mac_write_key); GUARD(s2n_hmac_reset(&conn->secure.server_record_mac)); GUARD(s2n_hmac_init(&conn->secure.server_record_mac, conn->secure.cipher_suite->record_alg->hmac_alg, server_mac_write_key, mac_size)); /* Make the client key */ GUARD(s2n_prf_make_client_key(conn, &key_material)); /* Make the server key */ GUARD(s2n_prf_make_server_key(conn, &key_material)); /* Composite CBC does MAC inside the cipher, pass it the MAC key. * Must happen after setting encryption/decryption keys. */ if (conn->secure.cipher_suite->record_alg->cipher->type == S2N_COMPOSITE) { GUARD(conn->secure.cipher_suite->record_alg->cipher->io.comp.set_mac_write_key(&conn->secure.server_key, server_mac_write_key, mac_size)); GUARD(conn->secure.cipher_suite->record_alg->cipher->io.comp.set_mac_write_key(&conn->secure.client_key, client_mac_write_key, mac_size)); } /* TLS >= 1.1 has no implicit IVs for non AEAD ciphers */ if (conn->actual_protocol_version > S2N_TLS10 && conn->secure.cipher_suite->record_alg->cipher->type != S2N_AEAD) { return 0; } uint32_t implicit_iv_size = 0; switch (conn->secure.cipher_suite->record_alg->cipher->type) { case S2N_AEAD: implicit_iv_size = conn->secure.cipher_suite->record_alg->cipher->io.aead.fixed_iv_size; break; case S2N_CBC: implicit_iv_size = conn->secure.cipher_suite->record_alg->cipher->io.cbc.block_size; break; case S2N_COMPOSITE: implicit_iv_size = conn->secure.cipher_suite->record_alg->cipher->io.comp.block_size; break; /* No-op for stream ciphers */ default: break; } struct s2n_blob client_implicit_iv = {.data = conn->secure.client_implicit_iv,.size = implicit_iv_size }; struct s2n_blob server_implicit_iv = {.data = conn->secure.server_implicit_iv,.size = implicit_iv_size }; GUARD(s2n_stuffer_read(&key_material, &client_implicit_iv)); GUARD(s2n_stuffer_read(&key_material, &server_implicit_iv)); return 0; }