From 2a873fd4e1d53c45898b27e1c953b551b2cf6023 Mon Sep 17 00:00:00 2001
From: Mark Haines <mark.haines@matrix.org>
Date: Tue, 7 Jul 2015 09:50:32 +0100
Subject: Add functions for creating and verifying ed25519 signatures

---
 include/olm/crypto.hh | 39 ++++++++++++++++++++++++++++++++++++++-
 src/crypto.cpp        | 36 ++++++++++++++++++++++++++++++++++++
 tests/test_crypto.cpp | 34 +++++++++++++++++++++++++++++++---
 3 files changed, 105 insertions(+), 4 deletions(-)

diff --git a/include/olm/crypto.hh b/include/olm/crypto.hh
index 7f8f069..b845bfe 100644
--- a/include/olm/crypto.hh
+++ b/include/olm/crypto.hh
@@ -33,6 +33,18 @@ struct Curve25519KeyPair : public Curve25519PublicKey {
 };
 
 
+struct Ed25519PublicKey {
+    static const int LENGTH = 32;
+    std::uint8_t public_key[32];
+};
+
+
+struct Ed25519KeyPair : public Ed25519PublicKey {
+    static const int LENGTH = 64;
+    std::uint8_t private_key[32];
+};
+
+
 /** Generate a curve25519 key pair from 32 random bytes. */
 void curve25519_generate_key(
     std::uint8_t const * random_32_bytes,
@@ -61,7 +73,7 @@ void curve25519_sign(
 );
 
 
-/** Verify thei message using their public key.
+/** Verify their message using their public key.
  * The signature input buffer must be 64 bytes long.
  * Returns true if the signature is valid. */
 bool curve25519_verify(
@@ -70,6 +82,31 @@ bool curve25519_verify(
     std::uint8_t const * signature
 );
 
+/** Generate a curve25519 key pair from 32 random bytes. */
+void ed25519_generate_key(
+    std::uint8_t const * random_32_bytes,
+    Ed25519KeyPair & key_pair
+);
+
+
+/** Signs the message using our private key.
+ * The output buffer must be at least 64 bytes long. */
+void ed25519_sign(
+    Ed25519KeyPair const & our_key,
+    std::uint8_t const * message, std::size_t message_length,
+    std::uint8_t * output
+);
+
+
+/** Verify their message using their public key.
+ * The signature input buffer must be 64 bytes long.
+ * Returns true if the signature is valid. */
+bool ed25519_verify(
+    Ed25519PublicKey const & their_key,
+    std::uint8_t const * message, std::size_t message_length,
+    std::uint8_t const * signature
+);
+
 
 struct Aes256Key {
     static const int LENGTH = 32;
diff --git a/src/crypto.cpp b/src/crypto.cpp
index db4bfa6..ed89d64 100644
--- a/src/crypto.cpp
+++ b/src/crypto.cpp
@@ -191,6 +191,42 @@ bool olm::curve25519_verify(
     );
 }
 
+
+void olm::ed25519_generate_key(
+    std::uint8_t const * random_32_bytes,
+    olm::Ed25519KeyPair & key_pair
+) {
+    std::memcpy(key_pair.private_key, random_32_bytes, 32);
+    ::ed25519_keypair(key_pair.private_key, key_pair.public_key);
+}
+
+
+void olm::ed25519_sign(
+    olm::Ed25519KeyPair const & our_key,
+    std::uint8_t const * message, std::size_t message_length,
+    std::uint8_t * output
+) {
+    ::ed25519_sign(
+        output,
+        message, message_length,
+        our_key.public_key, our_key.private_key
+    );
+}
+
+
+bool olm::ed25519_verify(
+    olm::Ed25519PublicKey const & their_key,
+    std::uint8_t const * message, std::size_t message_length,
+    std::uint8_t const * signature
+) {
+    return 0 != ::ed25519_verify(
+        signature,
+        message, message_length,
+        their_key.public_key
+    );
+}
+
+
 std::size_t olm::aes_encrypt_cbc_length(
     std::size_t input_length
 ) {
diff --git a/tests/test_crypto.cpp b/tests/test_crypto.cpp
index b8ffbcd..b3ff593 100644
--- a/tests/test_crypto.cpp
+++ b/tests/test_crypto.cpp
@@ -83,8 +83,8 @@ assert_equals(expected_agreement, actual_agreement, 32);
 } /* Curve25529 Test Case 1 */
 
 
-{ /* Signature Test Cast 1 */
-TestCase test_case("Signature Test Case 1");
+{ /* Curve25519 Signature Test Case 1 */
+TestCase test_case("Curve25519 Signature Test Case 1");
 
 std::uint8_t private_key[33] = "This key is a string of 32 bytes";
 std::uint8_t message[] = "message";
@@ -110,7 +110,35 @@ result = olm::curve25519_verify(
 );
 assert_equals(false, result);
 
-} /* Signature Test Cast 1 */
+} /* Curve25519 Signature Test Case 1 */
+
+{
+TestCase test_case("Ed25519 Signature Test Case 1");
+std::uint8_t private_key[33] = "This key is a string of 32 bytes";
+
+std::uint8_t message[] = "Hello, World";
+std::size_t message_length = sizeof(message) - 1;
+
+olm::Ed25519KeyPair key_pair;
+olm::ed25519_generate_key(private_key, key_pair);
+
+std::uint8_t signature[64];
+olm::ed25519_sign(
+    key_pair, message, message_length, signature
+);
+
+bool result = olm::ed25519_verify(
+    key_pair, message, message_length, signature
+);
+assert_equals(true, result);
+
+message[0] = 'n';
+result = olm::ed25519_verify(
+    key_pair, message, message_length, signature
+);
+assert_equals(false, result);
+}
+
 
 { /* AES Test Case 1 */
 
-- 
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