Give SHA256 functions C bindings

8 files changed, 100 insertions, 62 deletions

diff --git a/include/olm/crypto.h b/include/olm/crypto.h
new file mode 100644
index 0000000..1357834
--- /dev/null
+++ b/include/olm/crypto.h
@@ -0,0 +1,65 @@
+/* Copyright 2015 OpenMarket 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.
+ */
+
+/* C-compatible crpyto utility functions. At some point all of crypto.hh will
+ * move here.
+ */
+
+#ifndef OLM_CRYPTO_H_
+#define OLM_CRYPTO_H_
+
+#include <stdint.h>
+#include <stdlib.h>
+
+#ifdef __cplusplus
+extern "C" {
+#endif
+
+const size_t SHA256_OUTPUT_LENGTH = 32;
+
+/** Computes SHA-256 of the input. The output buffer must be a least 32
+ * bytes long. */
+void crypto_sha256(
+    uint8_t const * input, size_t input_length,
+    uint8_t * output
+);
+
+/** HMAC: Keyed-Hashing for Message Authentication
+ * http://tools.ietf.org/html/rfc2104
+ * Computes HMAC-SHA-256 of the input for the key. The output buffer must
+ * be at least 32 bytes long. */
+void crypto_hmac_sha256(
+    uint8_t const * key, size_t key_length,
+    uint8_t const * input, size_t input_length,
+    uint8_t * output
+);
+
+
+/** HMAC-based Key Derivation Function (HKDF)
+ * https://tools.ietf.org/html/rfc5869
+ * Derives key material from the input bytes. */
+void crypto_hkdf_sha256(
+    uint8_t const * input, size_t input_length,
+    uint8_t const * info, size_t info_length,
+    uint8_t const * salt, size_t salt_length,
+    uint8_t * output, size_t output_length
+);
+
+
+#ifdef __cplusplus
+} // extern "C"
+#endif
+
+#endif /* OLM_CRYPTO_H_ */
diff --git a/include/olm/crypto.hh b/include/olm/crypto.hh
index 7a05f8d..64e8f7d 100644
--- a/include/olm/crypto.hh
+++ b/include/olm/crypto.hh
@@ -18,6 +18,11 @@
 #include <cstdint>
 #include <cstddef>
 
+// eventually all of this needs to move into crypto.h, and everything should
+// use that. For now, include crypto.h here.
+
+#include "olm/crypto.h"
+
 namespace olm {
 
 static const std::size_t KEY_LENGTH = 32;
@@ -142,38 +147,6 @@ std::size_t aes_decrypt_cbc(
 );
 
 
-/** Computes SHA-256 of the input. The output buffer must be a least 32
- * bytes long. */
-void sha256(
-    std::uint8_t const * input, std::size_t input_length,
-    std::uint8_t * output
-);
-
-
-const std::size_t SHA256_OUTPUT_LENGTH = 32;
-
-
-/** HMAC: Keyed-Hashing for Message Authentication
- * http://tools.ietf.org/html/rfc2104
- * Computes HMAC-SHA-256 of the input for the key. The output buffer must
- * be at least 32 bytes long. */
-void hmac_sha256(
-    std::uint8_t const * key, std::size_t key_length,
-    std::uint8_t const * input, std::size_t input_length,
-    std::uint8_t * output
-);
-
-
-/** HMAC-based Key Derivation Function (HKDF)
- * https://tools.ietf.org/html/rfc5869
- * Derives key material from the input bytes. */
-void 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 * output, std::size_t output_length
-);
-
 } // namespace olm
 
 #endif /* OLM_CRYPTO_HH_ */
diff --git a/src/cipher.cpp b/src/cipher.cpp
index 7bb11b8..a550312 100644
--- a/src/cipher.cpp
+++ b/src/cipher.cpp
@@ -36,7 +36,7 @@ static void derive_keys(
     DerivedKeys & keys
 ) {
     std::uint8_t derived_secrets[2 * olm::KEY_LENGTH + olm::IV_LENGTH];
-    olm::hkdf_sha256(
+    crypto_hkdf_sha256(
         key, key_length,
         nullptr, 0,
         kdf_info, kdf_info_length,
@@ -83,7 +83,7 @@ std::size_t olm::CipherAesSha256::encrypt(
         return std::size_t(-1);
     }
     struct DerivedKeys keys;
-    std::uint8_t mac[olm::SHA256_OUTPUT_LENGTH];
+    std::uint8_t mac[SHA256_OUTPUT_LENGTH];
 
     derive_keys(kdf_info, kdf_info_length, key, key_length, keys);
 
@@ -91,7 +91,7 @@ std::size_t olm::CipherAesSha256::encrypt(
         keys.aes_key, keys.aes_iv, plaintext, plaintext_length, ciphertext
     );
 
-    olm::hmac_sha256(
+    crypto_hmac_sha256(
         keys.mac_key, olm::KEY_LENGTH, output, output_length - MAC_LENGTH, mac
     );
 
@@ -115,11 +115,11 @@ std::size_t olm::CipherAesSha256::decrypt(
      std::uint8_t * plaintext, std::size_t max_plaintext_length
 ) const {
     DerivedKeys keys;
-    std::uint8_t mac[olm::SHA256_OUTPUT_LENGTH];
+    std::uint8_t mac[SHA256_OUTPUT_LENGTH];
 
     derive_keys(kdf_info, kdf_info_length, key, key_length, keys);
 
-    olm::hmac_sha256(
+    crypto_hmac_sha256(
         keys.mac_key, olm::KEY_LENGTH, input, input_length - MAC_LENGTH, mac
     );
 
diff --git a/src/crypto.cpp b/src/crypto.cpp
index ffe2661..175b323 100644
--- a/src/crypto.cpp
+++ b/src/crypto.cpp
@@ -85,7 +85,7 @@ inline static void hmac_sha256_final(
     std::uint8_t const * hmac_key,
     std::uint8_t * output
 ) {
-    std::uint8_t o_pad[SHA256_BLOCK_LENGTH + olm::SHA256_OUTPUT_LENGTH];
+    std::uint8_t o_pad[SHA256_BLOCK_LENGTH + SHA256_OUTPUT_LENGTH];
     std::memcpy(o_pad, hmac_key, SHA256_BLOCK_LENGTH);
     for (std::size_t i = 0; i < SHA256_BLOCK_LENGTH; ++i) {
         o_pad[i] ^= 0x5C;
@@ -255,7 +255,7 @@ std::size_t olm::aes_decrypt_cbc(
 }
 
 
-void olm::sha256(
+void crypto_sha256(
     std::uint8_t const * input, std::size_t input_length,
     std::uint8_t * output
 ) {
@@ -267,7 +267,7 @@ void olm::sha256(
 }
 
 
-void olm::hmac_sha256(
+void crypto_hmac_sha256(
     std::uint8_t const * key, std::size_t key_length,
     std::uint8_t const * input, std::size_t input_length,
     std::uint8_t * output
@@ -283,7 +283,7 @@ void olm::hmac_sha256(
 }
 
 
-void olm::hkdf_sha256(
+void crypto_hkdf_sha256(
     std::uint8_t const * input, std::size_t input_length,
     std::uint8_t const * salt, std::size_t salt_length,
     std::uint8_t const * info, std::size_t info_length,
@@ -291,7 +291,7 @@ void olm::hkdf_sha256(
 ) {
     ::SHA256_CTX context;
     std::uint8_t hmac_key[SHA256_BLOCK_LENGTH];
-    std::uint8_t step_result[olm::SHA256_OUTPUT_LENGTH];
+    std::uint8_t step_result[SHA256_OUTPUT_LENGTH];
     std::size_t bytes_remaining = output_length;
     std::uint8_t iteration = 1;
     if (!salt) {
@@ -303,20 +303,20 @@ void olm::hkdf_sha256(
     hmac_sha256_init(&context, hmac_key);
     ::sha256_update(&context, input, input_length);
     hmac_sha256_final(&context, hmac_key, step_result);
-    hmac_sha256_key(step_result, olm::SHA256_OUTPUT_LENGTH, hmac_key);
+    hmac_sha256_key(step_result, SHA256_OUTPUT_LENGTH, hmac_key);
 
     /* Expand */
     hmac_sha256_init(&context, hmac_key);
     ::sha256_update(&context, info, info_length);
     ::sha256_update(&context, &iteration, 1);
     hmac_sha256_final(&context, hmac_key, step_result);
-    while (bytes_remaining > olm::SHA256_OUTPUT_LENGTH) {
-        std::memcpy(output, step_result, olm::SHA256_OUTPUT_LENGTH);
-        output += olm::SHA256_OUTPUT_LENGTH;
-        bytes_remaining -= olm::SHA256_OUTPUT_LENGTH;
+    while (bytes_remaining > SHA256_OUTPUT_LENGTH) {
+        std::memcpy(output, step_result, SHA256_OUTPUT_LENGTH);
+        output += SHA256_OUTPUT_LENGTH;
+        bytes_remaining -= SHA256_OUTPUT_LENGTH;
         iteration ++;
         hmac_sha256_init(&context, hmac_key);
-        ::sha256_update(&context, step_result, olm::SHA256_OUTPUT_LENGTH);
+        ::sha256_update(&context, step_result, SHA256_OUTPUT_LENGTH);
         ::sha256_update(&context, info, info_length);
         ::sha256_update(&context, &iteration, 1);
         hmac_sha256_final(&context, hmac_key, step_result);
diff --git a/src/ratchet.cpp b/src/ratchet.cpp
index b04099f..8b1f30b 100644
--- a/src/ratchet.cpp
+++ b/src/ratchet.cpp
@@ -50,7 +50,7 @@ static void create_chain_key(
     olm::SharedKey secret;
     olm::curve25519_shared_secret(our_key, their_key, secret);
     std::uint8_t derived_secrets[2 * olm::KEY_LENGTH];
-    olm::hkdf_sha256(
+    crypto_hkdf_sha256(
         secret, sizeof(secret),
         root_key, sizeof(root_key),
         info.ratchet_info, info.ratchet_info_length,
@@ -70,7 +70,7 @@ static void advance_chain_key(
     olm::ChainKey const & chain_key,
     olm::ChainKey & new_chain_key
 ) {
-    olm::hmac_sha256(
+    crypto_hmac_sha256(
         chain_key.key, sizeof(chain_key.key),
         CHAIN_KEY_SEED, sizeof(CHAIN_KEY_SEED),
         new_chain_key.key
@@ -84,7 +84,7 @@ static void create_message_keys(
     olm::ChainKey const & chain_key,
     olm::KdfInfo const & info,
     olm::MessageKey & message_key) {
-    olm::hmac_sha256(
+    crypto_hmac_sha256(
         chain_key.key, sizeof(chain_key.key),
         MESSAGE_KEY_SEED, sizeof(MESSAGE_KEY_SEED),
         message_key.key
@@ -195,7 +195,7 @@ void olm::Ratchet::initialise_as_bob(
     olm::Curve25519PublicKey const & their_ratchet_key
 ) {
     std::uint8_t derived_secrets[2 * olm::KEY_LENGTH];
-    olm::hkdf_sha256(
+    crypto_hkdf_sha256(
         shared_secret, shared_secret_length,
         nullptr, 0,
         kdf_info.root_info, kdf_info.root_info_length,
@@ -217,7 +217,7 @@ void olm::Ratchet::initialise_as_alice(
     olm::Curve25519KeyPair const & our_ratchet_key
 ) {
     std::uint8_t derived_secrets[2 * olm::KEY_LENGTH];
-    olm::hkdf_sha256(
+    crypto_hkdf_sha256(
         shared_secret, shared_secret_length,
         nullptr, 0,
         kdf_info.root_info, kdf_info.root_info_length,
diff --git a/src/session.cpp b/src/session.cpp
index 86ba63b..85c958c 100644
--- a/src/session.cpp
+++ b/src/session.cpp
@@ -192,7 +192,7 @@ std::size_t olm::Session::new_inbound_session(
 
 
 std::size_t olm::Session::session_id_length() {
-    return olm::SHA256_OUTPUT_LENGTH;
+    return SHA256_OUTPUT_LENGTH;
 }
 
 
@@ -208,7 +208,7 @@ std::size_t olm::Session::session_id(
     pos = olm::store_array(pos, alice_identity_key.public_key);
     pos = olm::store_array(pos, alice_base_key.public_key);
     pos = olm::store_array(pos, bob_one_time_key.public_key);
-    olm::sha256(tmp, sizeof(tmp), id);
+    crypto_sha256(tmp, sizeof(tmp), id);
     return session_id_length();
 }
 
diff --git a/src/utility.cpp b/src/utility.cpp
index bc51cff..2217778 100644
--- a/src/utility.cpp
+++ b/src/utility.cpp
@@ -23,7 +23,7 @@ olm::Utility::Utility(
 
 
 size_t olm::Utility::sha256_length() {
-    return olm::SHA256_OUTPUT_LENGTH;
+    return SHA256_OUTPUT_LENGTH;
 }
 
 
@@ -35,8 +35,8 @@ size_t olm::Utility::sha256(
         last_error = olm::ErrorCode::OUTPUT_BUFFER_TOO_SMALL;
         return std::size_t(-1);
     }
-    olm::sha256(input, input_length, output);
-    return olm::SHA256_OUTPUT_LENGTH;
+    crypto_sha256(input, input_length, output);
+    return SHA256_OUTPUT_LENGTH;
 }
 
 
diff --git a/tests/test_crypto.cpp b/tests/test_crypto.cpp
index 4606c52..e86f3ab 100644
--- a/tests/test_crypto.cpp
+++ b/tests/test_crypto.cpp
@@ -186,7 +186,7 @@ std::uint8_t expected[32] = {
 
 std::uint8_t actual[32];
 
-olm::sha256(input, sizeof(input), actual);
+crypto_sha256(input, sizeof(input), actual);
 
 assert_equals(expected, actual, 32);
 
@@ -207,7 +207,7 @@ std::uint8_t expected[32] = {
 
 std::uint8_t actual[32];
 
-olm::hmac_sha256(input, sizeof(input), input, sizeof(input), actual);
+crypto_hmac_sha256(input, sizeof(input), input, sizeof(input), actual);
 
 assert_equals(expected, actual, 32);
 
@@ -242,7 +242,7 @@ std::uint8_t hmac_expected_output[32] = {
 
 std::uint8_t hmac_actual_output[32] = {};
 
-olm::hmac_sha256(
+crypto_hmac_sha256(
     salt, sizeof(salt),
     input, sizeof(input),
     hmac_actual_output
@@ -261,7 +261,7 @@ std::uint8_t hkdf_expected_output[42] = {
 
 std::uint8_t hkdf_actual_output[42] = {};
 
-olm::hkdf_sha256(
+crypto_hkdf_sha256(
     input, sizeof(input),
     salt, sizeof(salt),
     info, sizeof(info),