From 94f664e7256215f33639dbbad6aaf87ada082a9f Mon Sep 17 00:00:00 2001 From: Hubert Chathi Date: Mon, 21 Jan 2019 23:21:41 -0500 Subject: initial implementation of short authentication string generation --- src/sas.c | 141 ++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 141 insertions(+) create mode 100644 src/sas.c (limited to 'src') diff --git a/src/sas.c b/src/sas.c new file mode 100644 index 0000000..c5be73f --- /dev/null +++ b/src/sas.c @@ -0,0 +1,141 @@ +/* Copyright 2018-2019 New Vector Ltd + * + * Licensed under the Apache License, Version 2.0 (the "License"); + * you may not use this file except in compliance with the License. + * You may obtain a copy of the License at + * + * http://www.apache.org/licenses/LICENSE-2.0 + * + * Unless required by applicable law or agreed to in writing, software + * distributed under the License is distributed on an "AS IS" BASIS, + * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. + * See the License for the specific language governing permissions and + * limitations under the License. + */ + +#include "olm/sas.h" +#include "olm/base64.h" +#include "olm/crypto.h" +#include "olm/error.h" +#include "olm/memory.h" + +struct OlmSAS { + enum OlmErrorCode last_error; + struct _olm_curve25519_key_pair curve25519_key; + uint8_t secret[CURVE25519_SHARED_SECRET_LENGTH]; +}; + +const char * olm_sas_last_error( + OlmSAS * sas +) { + return _olm_error_to_string(sas->last_error); +} + +size_t olm_sas_size(void) { + return sizeof(OlmSAS); +} + +OlmSAS * olm_sas( + void * memory +) { + _olm_unset(memory, sizeof(OlmSAS)); + return (OlmSAS *) memory; +} + +size_t olm_clear_sas( + OlmSAS * sas +) { + _olm_unset(sas, sizeof(OlmSAS)); + return sizeof(OlmSAS); +} + +size_t olm_create_sas_random_length(OlmSAS * sas) { + return CURVE25519_KEY_LENGTH; +} + +size_t olm_create_sas( + OlmSAS * sas, + void * random, size_t random_length +) { + if (random_length < olm_create_sas_random_length(sas)) { + sas->last_error = OLM_NOT_ENOUGH_RANDOM; + return (size_t)-1; + } + _olm_crypto_curve25519_generate_key((uint8_t *) random, &sas->curve25519_key); + return 0; +} + +size_t olm_sas_pubkey_length(OlmSAS * sas) { + return _olm_encode_base64_length(CURVE25519_KEY_LENGTH); +} + +size_t olm_sas_get_pubkey( + OlmSAS * sas, + void * pubkey, size_t pubkey_length +) { + if (pubkey_length < olm_sas_pubkey_length(sas)) { + sas->last_error = OLM_OUTPUT_BUFFER_TOO_SMALL; + return (size_t)-1; + } + _olm_encode_base64( + (const uint8_t *)sas->curve25519_key.public_key.public_key, + CURVE25519_KEY_LENGTH, + (uint8_t *)pubkey + ); + return 0; +} + +size_t olm_sas_set_their_key( + OlmSAS *sas, + void * their_key, size_t their_key_length +) { + if (their_key_length < olm_sas_pubkey_length(sas)) { + sas->last_error = OLM_INPUT_BUFFER_TOO_SMALL; + return (size_t)-1; + } + _olm_decode_base64(their_key, their_key_length, their_key); + _olm_crypto_curve25519_shared_secret(&sas->curve25519_key, their_key, sas->secret); + return 0; +} + +size_t olm_sas_generate_bytes( + OlmSAS * sas, + const void * info, size_t info_length, + void * output, size_t output_length +) { + _olm_crypto_hkdf_sha256( + sas->secret, sizeof(sas->secret), + NULL, 0, + (const uint8_t *) info, info_length, + output, output_length + ); + return 0; +} + +size_t olm_sas_mac_length( + OlmSAS *sas +) { + return _olm_encode_base64_length(SHA256_OUTPUT_LENGTH); +} + +size_t olm_sas_calculate_mac( + OlmSAS * sas, + void * input, size_t input_length, + const void * info, size_t info_length, + void * mac, size_t mac_length +) { + if (mac_length < olm_sas_mac_length(sas)) { + sas->last_error = OLM_OUTPUT_BUFFER_TOO_SMALL; + return (size_t)-1; + } + uint8_t key[32]; + _olm_crypto_hkdf_sha256( + sas->secret, sizeof(sas->secret), + NULL, 0, + (const uint8_t *) info, info_length, + key, 32 + ); + _olm_crypto_hmac_sha256(key, 32, input, input_length, mac); + _olm_encode_base64((const uint8_t *)mac, SHA256_OUTPUT_LENGTH, (uint8_t *)mac); + return 0; +} -- cgit v1.2.3