Add methods for computing sha256 hashes and validating ed25519 signatures

2 files changed, 95 insertions, 0 deletions

diff --git a/include/olm/olm.hh b/include/olm/olm.hh
index a5a50de..34d84fd 100644
--- a/include/olm/olm.hh
+++ b/include/olm/olm.hh
@@ -27,6 +27,7 @@ static const size_t OLM_MESSAGE_TYPE_MESSAGE = 1;
 
 struct OlmAccount;
 struct OlmSession;
+struct OlmUtility;
 
 /** The size of an account object in bytes */
 size_t olm_account_size();
@@ -34,6 +35,9 @@ size_t olm_account_size();
 /** The size of a session object in bytes */
 size_t olm_session_size();
 
+/** The size of a utility object in bytes */
+size_t olm_utility_size();
+
 /** Initialise an account object using the supplied memory
  *  The supplied memory must be at least olm_account_size() bytes */
 OlmAccount * olm_account(
@@ -46,6 +50,12 @@ OlmSession * olm_session(
     void * memory
 );
 
+/** Initialise a utility object using the supplied memory
+ *  The supplied memory must be at least olm_session_size() bytes */
+OlmUtility * olm_utility(
+    void * memory
+);
+
 /** The value that olm will return from a function if there was an error */
 size_t olm_error();
 
@@ -61,6 +71,12 @@ const char * olm_session_last_error(
     OlmSession * session
 );
 
+/** A null terminated string describing the most recent error to happen to a
+ * utility */
+const char * olm_utility_last_error(
+    OlmUtility * utility
+);
+
 /** Clears the memory used to back this account */
 size_t olm_clear_account(
     OlmAccount * account
@@ -71,6 +87,11 @@ size_t olm_clear_session(
     OlmSession * session
 );
 
+/** Clears the memory used to back this utility */
+size_t olm_clear_utility(
+    OlmUtility * utility
+);
+
 /** Returns the number of bytes needed to store an account */
 size_t olm_pickle_account_length(
     OlmAccount * account
@@ -370,7 +391,29 @@ size_t olm_decrypt(
     void * plaintext, size_t max_plaintext_length
 );
 
+/** The length of the buffer needed to hold the SHA-256 hash. */
+size_t olm_sha256_length(
+   OlmUtility * utility
+);
+
+/** Calculates the SHA-256 hash of the input and encodes it as base64. If the
+ * output buffer is smaller than olm_sha256_length() then
+ * olm_session_last_error() will be "OUTPUT_BUFFER_TOO_SMALL". */
+size_t olm_sha256(
+    OlmUtility * utility,
+    void const * input, size_t input_length,
+    void * output, size_t output_length
+);
 
+/** Verify an ed25519 signature. If the key was too small then
+ * olm_session_last_error will be "INVALID_BASE64". If the signature was invalid
+ * then olm_session_last_error() will be "BAD_MESSAGE_MAC". */
+size_t olm_ed25519_verify(
+    OlmUtility * utility,
+    void const * key, size_t key_length,
+    void const * message, size_t message_length,
+    void * signature, size_t signature_length
+);
 
 #ifdef __cplusplus
 }
diff --git a/include/olm/utility.hh b/include/olm/utility.hh
new file mode 100644
index 0000000..241d7e0
--- /dev/null
+++ b/include/olm/utility.hh
@@ -0,0 +1,52 @@
+/* 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.
+ */
+
+#ifndef UTILITY_HH_
+#define UTILITY_HH_
+
+#include "olm/error.hh"
+
+#include <cstddef>
+#include <cstdint>
+
+namespace olm {
+
+class Ed25519PublicKey;
+
+struct Utility {
+
+    Utility();
+
+    ErrorCode last_error;
+
+    std::size_t sha256_length();
+
+    std::size_t sha256(
+        std::uint8_t const * input, std::size_t input_length,
+        std::uint8_t * output, std::size_t output_length
+    );
+
+    std::size_t ed25519_verify(
+        Ed25519PublicKey const & key,
+        std::uint8_t const * message, std::size_t message_length,
+        std::uint8_t const * signature, std::size_t signature_length
+    );
+
+};
+
+
+} // namespace olm
+
+#endif /* UTILITY_HH_ */