Torne (Richard Coles) | 2a99a7e | 2013-03-28 15:31:22 +0000 | [diff] [blame] | 1 | // Copyright (c) 2013 The Chromium Authors. All rights reserved. |
| 2 | // Use of this source code is governed by a BSD-style license that can be |
| 3 | // found in the LICENSE file. |
| 4 | |
| 5 | #ifndef CRYPTO_CURVE25519_H |
| 6 | #define CRYPTO_CURVE25519_H |
| 7 | |
| 8 | #include "base/basictypes.h" |
| 9 | #include "crypto/crypto_export.h" |
| 10 | |
| 11 | namespace crypto { |
| 12 | |
| 13 | // Curve25519 implements the elliptic curve group known as Curve25519, as |
| 14 | // described in "Curve 25519: new Diffie-Hellman Speed Records", |
| 15 | // by D.J. Bernstein. Additional information is available at |
| 16 | // http://cr.yp.to/ecdh.html. |
| 17 | namespace curve25519 { |
| 18 | |
| 19 | // kBytes is the number of bytes in the result of the Diffie-Hellman operation, |
| 20 | // which is an element of GF(2^255-19). |
| 21 | static const size_t kBytes = 32; |
| 22 | |
| 23 | // kScalarBytes is the number of bytes in an element of the scalar field: |
| 24 | // GF(2^252 + 27742317777372353535851937790883648493). |
| 25 | static const size_t kScalarBytes = 32; |
| 26 | |
| 27 | // ScalarMult computes the |shared_key| from |private_key| and |
| 28 | // |peer_public_key|. This method is a wrapper for |curve25519_donna()|. It |
| 29 | // calls that function with |private_key| as |secret| and |peer_public_key| as |
| 30 | // basepoint. |private_key| should be of length |kScalarBytes| and |
| 31 | // |peer_public_key| should be of length |kBytes|. |
| 32 | // See "Computing shared secrets" section of/ http://cr.yp.to/ecdh.html. |
| 33 | CRYPTO_EXPORT void ScalarMult(const uint8* private_key, |
| 34 | const uint8* peer_public_key, |
| 35 | uint8* shared_key); |
| 36 | |
| 37 | // ScalarBaseMult computes the |public_key| from |private_key|. This method is a |
| 38 | // wrapper for |curve25519_donna()|. It calls that function with |private_key| |
| 39 | // as |secret| and |kBasePoint| as basepoint. |private_key| should be of length |
| 40 | // |kScalarBytes|. See "Computing public keys" section of |
| 41 | // http://cr.yp.to/ecdh.html. |
| 42 | CRYPTO_EXPORT void ScalarBaseMult(const uint8* private_key, uint8* public_key); |
| 43 | |
| 44 | } // namespace curve25519 |
| 45 | |
| 46 | } // namespace crypto |
| 47 | |
| 48 | #endif // CRYPTO_CURVE25519_H |