diff options
Diffstat (limited to 'src')
| -rw-r--r-- | src/crypto.cpp | 59 |
1 files changed, 35 insertions, 24 deletions
diff --git a/src/crypto.cpp b/src/crypto.cpp index c1ef88a..5277b86 100644 --- a/src/crypto.cpp +++ b/src/crypto.cpp @@ -19,7 +19,8 @@ namespace { static const std::uint8_t CURVE25519_BASEPOINT[32] = {9}; static const std::size_t AES_BLOCK_LENGTH = 16; -static const std::size_t SHA256_BLOCK_LENGTH = 32; +static const std::size_t SHA256_HASH_LENGTH = 32; +static const std::size_t SHA256_BLOCK_LENGTH = 64; static const std::uint8_t HKDF_DEFAULT_SALT[32] = {}; template<std::size_t block_size> @@ -37,13 +38,13 @@ inline static void hmac_sha256_key( std::uint8_t const * input_key, std::size_t input_key_length, std::uint8_t * hmac_key ) { + std::memset(hmac_key, 0, SHA256_BLOCK_LENGTH); if (input_key_length > SHA256_BLOCK_LENGTH) { ::SHA256_CTX context; ::sha256_init(&context); ::sha256_update(&context, input_key, input_key_length); ::sha256_final(&context, hmac_key); } else { - std::memset(hmac_key, 0, SHA256_BLOCK_LENGTH); std::memcpy(hmac_key, input_key, input_key_length); } } @@ -56,7 +57,7 @@ inline void hmac_sha256_init( std::uint8_t i_pad[SHA256_BLOCK_LENGTH]; std::memcpy(i_pad, hmac_key, SHA256_BLOCK_LENGTH); for (std::size_t i = 0; i < SHA256_BLOCK_LENGTH; ++i) { - i_pad[i] ^= 0x5C; + i_pad[i] ^= 0x36; } ::sha256_init(context); ::sha256_update(context, i_pad, SHA256_BLOCK_LENGTH); @@ -69,16 +70,15 @@ inline void hmac_sha256_final( std::uint8_t const * hmac_key, std::uint8_t * output ) { - std::uint8_t o_pad[SHA256_BLOCK_LENGTH]; + std::uint8_t o_pad[SHA256_BLOCK_LENGTH + SHA256_HASH_LENGTH]; std::memcpy(o_pad, hmac_key, SHA256_BLOCK_LENGTH); for (std::size_t i = 0; i < SHA256_BLOCK_LENGTH; ++i) { - o_pad[i] ^= 0x36; + o_pad[i] ^= 0x5C; } + ::sha256_final(context, o_pad + SHA256_BLOCK_LENGTH); ::SHA256_CTX final_context; ::sha256_init(&final_context); - ::sha256_update(&final_context, o_pad, SHA256_BLOCK_LENGTH); - ::sha256_final(context, o_pad); - ::sha256_update(&final_context, o_pad, SHA256_BLOCK_LENGTH); + ::sha256_update(&final_context, o_pad, sizeof(o_pad)); ::sha256_final(&final_context, output); std::memset(o_pad, 0, sizeof(o_pad)); } @@ -167,6 +167,16 @@ void axolotl::aes_decrypt_cbc( } +void axolotl::sha256( + std::uint8_t const * input, std::size_t input_length, + std::uint8_t * output +) { + ::SHA256_CTX context; + ::sha256_init(&context); + ::sha256_update(&context, input, input_length); + ::sha256_final(&context, output); +} + void axolotl::hmac_sha256( std::uint8_t const * key, std::size_t key_length, std::uint8_t const * input, std::size_t input_length, @@ -184,14 +194,13 @@ void axolotl::hmac_sha256( void axolotl::hkdf_sha256( std::uint8_t const * input, std::size_t input_length, - std::uint8_t const * info, std::size_t info_length, std::uint8_t const * salt, std::size_t salt_length, + std::uint8_t const * info, std::size_t info_length, std::uint8_t * output, std::size_t output_length ) { ::SHA256_CTX context; - std::uint8_t extract_key[SHA256_BLOCK_LENGTH]; - std::uint8_t expand_key[SHA256_BLOCK_LENGTH]; - std::uint8_t step_result[SHA256_BLOCK_LENGTH]; + std::uint8_t hmac_key[SHA256_BLOCK_LENGTH]; + std::uint8_t step_result[SHA256_HASH_LENGTH]; std::size_t bytes_remaining = output_length; std::uint8_t iteration = 1; if (!salt) { @@ -199,25 +208,27 @@ void axolotl::hkdf_sha256( salt_length = sizeof(HKDF_DEFAULT_SALT); } /* Expand */ - hmac_sha256_key(salt, salt_length, extract_key); - hmac_sha256_init(&context, extract_key); + hmac_sha256_key(salt, salt_length, hmac_key); + hmac_sha256_init(&context, hmac_key); ::sha256_update(&context, input, input_length); - hmac_sha256_final(&context, extract_key, expand_key); + hmac_sha256_final(&context, hmac_key, step_result); + hmac_sha256_key(step_result, SHA256_HASH_LENGTH, hmac_key); + /* Extract */ - hmac_sha256_init(&context, expand_key); + hmac_sha256_init(&context, hmac_key); ::sha256_update(&context, info, info_length); ::sha256_update(&context, &iteration, 1); - hmac_sha256_final(&context, expand_key, step_result); - while (bytes_remaining > SHA256_BLOCK_LENGTH) { - std::memcpy(output, step_result, SHA256_BLOCK_LENGTH); - output += SHA256_BLOCK_LENGTH; - bytes_remaining -= SHA256_BLOCK_LENGTH; + hmac_sha256_final(&context, hmac_key, step_result); + while (bytes_remaining > SHA256_HASH_LENGTH) { + std::memcpy(output, step_result, SHA256_HASH_LENGTH); + output += SHA256_HASH_LENGTH; + bytes_remaining -= SHA256_HASH_LENGTH; iteration ++; - hmac_sha256_init(&context, expand_key); - ::sha256_update(&context, step_result, SHA256_BLOCK_LENGTH); + hmac_sha256_init(&context, hmac_key); + ::sha256_update(&context, step_result, SHA256_HASH_LENGTH); ::sha256_update(&context, info, info_length); ::sha256_update(&context, &iteration, 1); - hmac_sha256_final(&context, expand_key, step_result); + hmac_sha256_final(&context, hmac_key, step_result); } std::memcpy(output, step_result, bytes_remaining); } |