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MySQL 5.1: mysql/src/5.1-dbg/extra/yassl/taocrypt/src/dh.cpp Source File
mysql/src/5.1-dbg/extra/yassl/taocrypt/src/dh.cpp

00001 /* dh.cpp                                
00002  *
00003  * Copyright (C) 2003 Sawtooth Consulting Ltd.
00004  *
00005  * This file is part of yaSSL.
00006  *
00007  * yaSSL is free software; you can redistribute it and/or modify
00008  * it under the terms of the GNU General Public License as published by
00009  * the Free Software Foundation; either version 2 of the License, or
00010  * (at your option) any later version.
00011  *
00012  * There are special exceptions to the terms and conditions of the GPL as it
00013  * is applied to yaSSL. View the full text of the exception in the file
00014  * FLOSS-EXCEPTIONS in the directory of this software distribution.
00015  *
00016  * yaSSL is distributed in the hope that it will be useful,
00017  * but WITHOUT ANY WARRANTY; without even the implied warranty of
00018  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
00019  * GNU General Public License for more details.
00020  *
00021  * You should have received a copy of the GNU General Public License
00022  * along with this program; if not, write to the Free Software
00023  * Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA
00024  */
00025 
00026 
00027 /* dh.cpp implements Diffie-Hellman support
00028 */
00029 
00030 #include "runtime.hpp"
00031 #include "dh.hpp"
00032 #include "asn.hpp"
00033 #include <math.h>
00034 
00035 namespace TaoCrypt {
00036 
00037 
00038 namespace {  // locals
00039 
00040 unsigned int DiscreteLogWorkFactor(unsigned int n)
00041 {
00042     // assuming discrete log takes about the same time as factoring
00043     if (n<5)
00044         return 0;
00045     else
00046         return (unsigned int)(2.4 * pow((double)n, 1.0/3.0) *
00047                 pow(log(double(n)), 2.0/3.0) - 5);
00048 }
00049 
00050 } // namespace locals
00051 
00052 
00053 // Generate a DH Key Pair
00054 void DH::GenerateKeyPair(RandomNumberGenerator& rng, byte* priv, byte* pub)
00055 {
00056     GeneratePrivate(rng, priv);
00057     GeneratePublic(priv, pub);
00058 }
00059 
00060 
00061 // Generate private value
00062 void DH::GeneratePrivate(RandomNumberGenerator& rng, byte* priv)
00063 {
00064     Integer x(rng, Integer::One(), mySTL::min(p_ - 1,
00065         Integer::Power2(2*DiscreteLogWorkFactor(p_.BitCount())) ) );
00066     x.Encode(priv, p_.ByteCount());
00067 }
00068 
00069 
00070 // Generate public value
00071 void DH::GeneratePublic(const byte* priv, byte* pub)
00072 {
00073     const word32 bc(p_.ByteCount());
00074     Integer x(priv, bc);
00075     Integer y(a_exp_b_mod_c(g_, x, p_));
00076     y.Encode(pub, bc);
00077 }
00078 
00079 
00080 // Generate Agreement
00081 void DH::Agree(byte* agree, const byte* priv, const byte* otherPub, word32
00082                otherSz)
00083 {
00084     const word32 bc(p_.ByteCount());
00085     Integer x(priv, bc);
00086     Integer y;
00087     if (otherSz)
00088         y.Decode(otherPub, otherSz);
00089     else
00090         y.Decode(otherPub, bc);
00091 
00092     Integer z(a_exp_b_mod_c(y, x, p_));
00093     z.Encode(agree, bc);
00094 }
00095 
00096 
00097 DH::DH(Source& source)
00098 {
00099     Initialize(source);
00100 }
00101 
00102 
00103 void DH::Initialize(Source& source)
00104 {
00105     DH_Decoder decoder(source);
00106     decoder.Decode(*this);
00107 }
00108 
00109 
00110 } // namespace
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