Curve25519-donna changes.

crypto/curve25519_unittest.cc

+// Copyright (c) 2013 The Chromium Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+#include "crypto/curve25519.h"
+
+#include <string>
+
+#include "crypto/random.h"
+#include "testing/gtest/include/gtest/gtest.h"
+
+namespace crypto {
+
+// Test that the basic shared key exchange identity holds: that both parties end
+// up with the same shared key. This test starts with a fixed private key for
+// two parties: alice and bob. Runs ScalarBaseMult and ScalarMult to compute
+// public key and shared key for alice and bob. It asserts that alice and bob
+// have the same shared key.
+TEST(Curve25519, SharedKeyIdentity) {
+  uint8 alice_private_key[curve25519::kScalarBytes] = {3};
+  uint8 bob_private_key[curve25519::kScalarBytes] = {5};
+
+  // Get public key for alice and bob.
+  uint8 alice_public_key[curve25519::kBytes];
+  curve25519::ScalarBaseMult(alice_private_key, alice_public_key);
+
+  uint8 bob_public_key[curve25519::kBytes];
+  curve25519::ScalarBaseMult(bob_private_key, bob_public_key);
+
+  // Get the shared key for alice, by using alice's private key and bob's
+  // public key.
+  uint8 alice_shared_key[curve25519::kBytes];
+  curve25519::ScalarMult(alice_private_key, bob_public_key, alice_shared_key);
+  std::string alice_shared;
+  alice_shared.assign(reinterpret_cast<char*>(alice_shared_key),
+                      sizeof(alice_shared_key));
+
+  // Get the shared key for bob, by using bob's private key and alice's public
+  // key.
+  uint8 bob_shared_key[curve25519::kBytes];
+  curve25519::ScalarMult(bob_private_key, alice_public_key, bob_shared_key);
+  std::string bob_shared;
+  bob_shared.assign(reinterpret_cast<char*>(bob_shared_key),
+                    sizeof(bob_shared_key));
+
+  // Computed shared key of alice and bob should be the same.
+  ASSERT_EQ(alice_shared, bob_shared);

[Ryan Sleevi, 2013/03/08 18:37:27]

Since |bob_shared| and |alice_shared| may contain arbitrary bytes, you may not
wish to use ASSERT_EQ (which will log the byte strings and their differences).

ASSERT_EQ(0, memcmp(alice_shared, bob_shared, alice_shared.size()))

This is minor though.

[ramant (doing other things), 2013/03/08 19:09:45]

Done.

+}
+
+}  // namespace crypto