juce/source/src/cryptography/juce_RSAKey.cpp

   1 /*
   2   ==============================================================================
   3
   4    This file is part of the JUCE library - "Jules' Utility Class Extensions"
   5    Copyright 2004-11 by Raw Material Software Ltd.
   6
   7   ------------------------------------------------------------------------------
   8
   9    JUCE can be redistributed and/or modified under the terms of the GNU General
  10    Public License (Version 2), as published by the Free Software Foundation.
  11    A copy of the license is included in the JUCE distribution, or can be found
  12    online at www.gnu.org/licenses.
  13
  14    JUCE is distributed in the hope that it will be useful, but WITHOUT ANY
  15    WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR
  16    A PARTICULAR PURPOSE.  See the GNU General Public License for more details.
  17
  18   ------------------------------------------------------------------------------
  19
  20    To release a closed-source product which uses JUCE, commercial licenses are
  21    available: visit www.rawmaterialsoftware.com/juce for more information.
  22
  23   ==============================================================================
  24 */
  25
  26 #include "../core/juce_StandardHeader.h"
  27
  28 BEGIN_JUCE_NAMESPACE
  29
  30 #include "juce_RSAKey.h"
  31 #include "juce_Primes.h"
  32
  33
  34 //==============================================================================
  35 RSAKey::RSAKey()
  36 {
  37 }
  38
  39 RSAKey::RSAKey (const String& s)
  40 {
  41     if (s.containsChar (','))
  42     {
  43         part1.parseString (s.upToFirstOccurrenceOf (",", false, false), 16);
  44         part2.parseString (s.fromFirstOccurrenceOf (",", false, false), 16);
  45     }
  46     else
  47     {
  48         // the string needs to be two hex numbers, comma-separated..
  49         jassertfalse;
  50     }
  51 }
  52
  53 RSAKey::~RSAKey()
  54 {
  55 }
  56
  57 bool RSAKey::operator== (const RSAKey& other) const noexcept
  58 {
  59     return part1 == other.part1 && part2 == other.part2;
  60 }
  61
  62 bool RSAKey::operator!= (const RSAKey& other) const noexcept
  63 {
  64     return ! operator== (other);
  65 }
  66
  67 String RSAKey::toString() const
  68 {
  69     return part1.toString (16) + "," + part2.toString (16);
  70 }
  71
  72 bool RSAKey::applyToValue (BigInteger& value) const
  73 {
  74     if (part1.isZero() || part2.isZero() || value <= 0)
  75     {
  76         jassertfalse;   // using an uninitialised key
  77         value.clear();
  78         return false;
  79     }
  80
  81     BigInteger result;
  82
  83     while (! value.isZero())
  84     {
  85         result *= part2;
  86
  87         BigInteger remainder;
  88         value.divideBy (part2, remainder);
  89
  90         remainder.exponentModulo (part1, part2);
  91
  92         result += remainder;
  93     }
  94
  95     value.swapWith (result);
  96     return true;
  97 }
  98
  99 BigInteger RSAKey::findBestCommonDivisor (const BigInteger& p, const BigInteger& q)
 100 {
 101     // try 3, 5, 9, 17, etc first because these only contain 2 bits and so
 102     // are fast to divide + multiply
 103     for (int i = 2; i <= 65536; i *= 2)
 104     {
 105         const BigInteger e (1 + i);
 106
 107         if (e.findGreatestCommonDivisor (p).isOne() && e.findGreatestCommonDivisor (q).isOne())
 108             return e;
 109     }
 110
 111     BigInteger e (4);
 112
 113     while (! (e.findGreatestCommonDivisor (p).isOne() && e.findGreatestCommonDivisor (q).isOne()))
 114         ++e;
 115
 116     return e;
 117 }
 118
 119 void RSAKey::createKeyPair (RSAKey& publicKey, RSAKey& privateKey,
 120                             const int numBits, const int* randomSeeds, const int numRandomSeeds)
 121 {
 122     jassert (numBits > 16); // not much point using less than this..
 123     jassert (numRandomSeeds == 0 || numRandomSeeds >= 2); // you need to provide plenty of seeds here!
 124
 125     BigInteger p (Primes::createProbablePrime (numBits / 2, 30, randomSeeds, numRandomSeeds / 2));
 126     BigInteger q (Primes::createProbablePrime (numBits - numBits / 2, 30, randomSeeds == nullptr ? 0 : (randomSeeds + numRandomSeeds / 2), numRandomSeeds - numRandomSeeds / 2));
 127
 128     const BigInteger n (p * q);
 129     const BigInteger m (--p * --q);
 130     const BigInteger e (findBestCommonDivisor (p, q));
 131
 132     BigInteger d (e);
 133     d.inverseModulo (m);
 134
 135     publicKey.part1 = e;
 136     publicKey.part2 = n;
 137
 138     privateKey.part1 = d;
 139     privateKey.part2 = n;
 140 }
 141
 142
 143 END_JUCE_NAMESPACE