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 49
