Added Curve25519-donna changes.

Added a wrapper class that implements the following API calls which for
Curve25519.
+ ScalarMult to compute the shared key.
+ ScalarBaseMult to get public key.
+ ConvertToPrivateKey returns a private key from random bytes.

Per agl/wtc, grabbed the rev 234205ff from the git repo
(https://github.com/agl/curve25519-donna/tree/234205ff1ecaf6b3c1dc76798a462c4293f31fdb)
and checked it in to crypto/ because that version has pure Google copyright.

R=wtc@chromium.org,agl@chromium.org,rsleevi@chromium.org
TEST=crypto unit tests

Review URL: https://chromiumcodereview.appspot.com/12457004

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@187074 0039d316-1c4b-4281-b951-d872f2087c98

1 files changed, 44 insertions, 0 deletions

diff --git a/crypto/curve25519_unittest.cc b/crypto/curve25519_unittest.cc
new file mode 100644
index 0000000..0ddc422
--- /dev/null
+++ b/crypto/curve25519_unittest.cc
@@ -0,0 +1,44 @@
+// 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);
+
+  // 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);
+
+  // Computed shared key of alice and bob should be the same.
+  ASSERT_EQ(0, memcmp(alice_shared_key, bob_shared_key, curve25519::kBytes));
+}
+
+}  // namespace crypto