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/*
==============================================================================
This file is part of the JUCE library.
Copyright (c) 2017 - ROLI Ltd.
JUCE is an open source library subject to commercial or open-source
licensing.
By using JUCE, you agree to the terms of both the JUCE 5 End-User License
Agreement and JUCE 5 Privacy Policy (both updated and effective as of the
27th April 2017).
End User License Agreement: www.juce.com/juce-5-licence
Privacy Policy: www.juce.com/juce-5-privacy-policy
Or: You may also use this code under the terms of the GPL v3 (see
www.gnu.org/licenses).
JUCE IS PROVIDED "AS IS" WITHOUT ANY WARRANTY, AND ALL WARRANTIES, WHETHER
EXPRESSED OR IMPLIED, INCLUDING MERCHANTABILITY AND FITNESS FOR PURPOSE, ARE
DISCLAIMED.
==============================================================================
*/
namespace juce
{
RSAKey::RSAKey()
{
}
RSAKey::RSAKey (const String& s)
{
if (s.containsChar (','))
{
part1.parseString (s.upToFirstOccurrenceOf (",", false, false), 16);
part2.parseString (s.fromFirstOccurrenceOf (",", false, false), 16);
}
else
{
// the string needs to be two hex numbers, comma-separated..
jassertfalse;
}
}
RSAKey::~RSAKey()
{
}
bool RSAKey::operator== (const RSAKey& other) const noexcept
{
return part1 == other.part1 && part2 == other.part2;
}
bool RSAKey::operator!= (const RSAKey& other) const noexcept
{
return ! operator== (other);
}
bool RSAKey::isValid() const noexcept
{
return operator!= (RSAKey());
}
String RSAKey::toString() const
{
return part1.toString (16) + "," + part2.toString (16);
}
bool RSAKey::applyToValue (BigInteger& value) const
{
if (part1.isZero() || part2.isZero() || value <= 0)
{
jassertfalse; // using an uninitialised key
value.clear();
return false;
}
BigInteger result;
while (! value.isZero())
{
result *= part2;
BigInteger remainder;
value.divideBy (part2, remainder);
remainder.exponentModulo (part1, part2);
result += remainder;
}
value.swapWith (result);
return true;
}
BigInteger RSAKey::findBestCommonDivisor (const BigInteger& p, const BigInteger& q)
{
// try 3, 5, 9, 17, etc first because these only contain 2 bits and so
// are fast to divide + multiply
for (int i = 2; i <= 65536; i *= 2)
{
const BigInteger e (1 + i);
if (e.findGreatestCommonDivisor (p).isOne() && e.findGreatestCommonDivisor (q).isOne())
return e;
}
BigInteger e (4);
while (! (e.findGreatestCommonDivisor (p).isOne() && e.findGreatestCommonDivisor (q).isOne()))
++e;
return e;
}
void RSAKey::createKeyPair (RSAKey& publicKey, RSAKey& privateKey,
const int numBits, const int* randomSeeds, const int numRandomSeeds)
{
jassert (numBits > 16); // not much point using less than this..
jassert (numRandomSeeds == 0 || numRandomSeeds >= 2); // you need to provide plenty of seeds here!
BigInteger p (Primes::createProbablePrime (numBits / 2, 30, randomSeeds, numRandomSeeds / 2));
BigInteger q (Primes::createProbablePrime (numBits - numBits / 2, 30, randomSeeds == nullptr ? nullptr : (randomSeeds + numRandomSeeds / 2), numRandomSeeds - numRandomSeeds / 2));
const BigInteger n (p * q);
const BigInteger m (--p * --q);
const BigInteger e (findBestCommonDivisor (p, q));
BigInteger d (e);
d.inverseModulo (m);
publicKey.part1 = e;
publicKey.part2 = n;
privateKey.part1 = d;
privateKey.part2 = n;
}
} // namespace juce
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