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, 48 insertions, 0 deletions

diff --git a/crypto/curve25519.h b/crypto/curve25519.h
new file mode 100644
index 0000000..ba24c92
--- /dev/null
+++ b/crypto/curve25519.h
@@ -0,0 +1,48 @@
+// 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.
+
+#ifndef CRYPTO_CURVE25519_H
+#define CRYPTO_CURVE25519_H
+
+#include "base/basictypes.h"
+#include "crypto/crypto_export.h"
+
+namespace crypto {
+
+// Curve25519 implements the elliptic curve group known as Curve25519, as
+// described in "Curve 25519: new Diffie-Hellman Speed Records",
+// by D.J. Bernstein. Additional information is available at
+// http://cr.yp.to/ecdh.html.
+namespace curve25519 {
+
+// kBytes is the number of bytes in the result of the Diffie-Hellman operation,
+// which is an element of GF(2^255-19).
+static const size_t kBytes = 32;
+
+// kScalarBytes is the number of bytes in an element of the scalar field:
+// GF(2^252 + 27742317777372353535851937790883648493).
+static const size_t kScalarBytes = 32;
+
+// ScalarMult computes the |shared_key| from |private_key| and
+// |peer_public_key|. This method is a wrapper for |curve25519_donna()|. It
+// calls that function with |private_key| as |secret| and |peer_public_key| as
+// basepoint. |private_key| should be of length |kScalarBytes| and
+// |peer_public_key| should be of length |kBytes|.
+// See "Computing shared secrets" section of/ http://cr.yp.to/ecdh.html.
+CRYPTO_EXPORT void ScalarMult(const uint8* private_key,
+                              const uint8* peer_public_key,
+                              uint8* shared_key);
+
+// ScalarBaseMult computes the |public_key| from |private_key|. This method is a
+// wrapper for |curve25519_donna()|. It calls that function with |private_key|
+// as |secret| and |kBasePoint| as basepoint. |private_key| should be of length
+// |kScalarBytes|. See "Computing public keys" section of
+// http://cr.yp.to/ecdh.html.
+CRYPTO_EXPORT void ScalarBaseMult(const uint8* private_key, uint8* public_key);
+
+}  // namespace curve25519
+
+}  // namespace crypto
+
+#endif  // CRYPTO_CURVE25519_H