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-rw-r--r--src/crypto.cpp59
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);
}