mirror of
https://github.com/shadps4-emu/ext-cryptopp.git
synced 2024-11-30 05:10:40 +00:00
81b1a18063
We have made a fair number of changes, and we don't want WD to receive credit for issues he was not part of
104 lines
3.0 KiB
C++
104 lines
3.0 KiB
C++
// xtr.cpp - originally written and placed in the public domain by Wei Dai
|
|
|
|
#include "pch.h"
|
|
|
|
#include "xtr.h"
|
|
#include "nbtheory.h"
|
|
#include "integer.h"
|
|
#include "algebra.h"
|
|
#include "modarith.h"
|
|
#include "algebra.cpp"
|
|
|
|
NAMESPACE_BEGIN(CryptoPP)
|
|
|
|
const GFP2Element & GFP2Element::Zero()
|
|
{
|
|
return Singleton<GFP2Element>().Ref();
|
|
}
|
|
|
|
void XTR_FindPrimesAndGenerator(RandomNumberGenerator &rng, Integer &p, Integer &q, GFP2Element &g, unsigned int pbits, unsigned int qbits)
|
|
{
|
|
CRYPTOPP_ASSERT(qbits > 9); // no primes exist for pbits = 10, qbits = 9
|
|
CRYPTOPP_ASSERT(pbits > qbits);
|
|
|
|
const Integer minQ = Integer::Power2(qbits - 1);
|
|
const Integer maxQ = Integer::Power2(qbits) - 1;
|
|
const Integer minP = Integer::Power2(pbits - 1);
|
|
const Integer maxP = Integer::Power2(pbits) - 1;
|
|
|
|
Integer r1, r2;
|
|
do
|
|
{
|
|
bool qFound = q.Randomize(rng, minQ, maxQ, Integer::PRIME, 7, 12);
|
|
CRYPTOPP_UNUSED(qFound); CRYPTOPP_ASSERT(qFound);
|
|
bool solutionsExist = SolveModularQuadraticEquation(r1, r2, 1, -1, 1, q);
|
|
CRYPTOPP_UNUSED(solutionsExist); CRYPTOPP_ASSERT(solutionsExist);
|
|
} while (!p.Randomize(rng, minP, maxP, Integer::PRIME, CRT(rng.GenerateBit()?r1:r2, q, 2, 3, EuclideanMultiplicativeInverse(p, 3)), 3*q));
|
|
CRYPTOPP_ASSERT(((p.Squared() - p + 1) % q).IsZero());
|
|
|
|
GFP2_ONB<ModularArithmetic> gfp2(p);
|
|
GFP2Element three = gfp2.ConvertIn(3), t;
|
|
|
|
while (true)
|
|
{
|
|
g.c1.Randomize(rng, Integer::Zero(), p-1);
|
|
g.c2.Randomize(rng, Integer::Zero(), p-1);
|
|
t = XTR_Exponentiate(g, p+1, p);
|
|
if (t.c1 == t.c2)
|
|
continue;
|
|
g = XTR_Exponentiate(g, (p.Squared()-p+1)/q, p);
|
|
if (g != three)
|
|
break;
|
|
}
|
|
CRYPTOPP_ASSERT(XTR_Exponentiate(g, q, p) == three);
|
|
}
|
|
|
|
GFP2Element XTR_Exponentiate(const GFP2Element &b, const Integer &e, const Integer &p)
|
|
{
|
|
unsigned int bitCount = e.BitCount();
|
|
if (bitCount == 0)
|
|
return GFP2Element(-3, -3);
|
|
|
|
// find the lowest bit of e that is 1
|
|
unsigned int lowest1bit;
|
|
for (lowest1bit=0; e.GetBit(lowest1bit) == 0; lowest1bit++) {}
|
|
|
|
GFP2_ONB<MontgomeryRepresentation> gfp2(p);
|
|
GFP2Element c = gfp2.ConvertIn(b);
|
|
GFP2Element cp = gfp2.PthPower(c);
|
|
GFP2Element S[5] = {gfp2.ConvertIn(3), c, gfp2.SpecialOperation1(c)};
|
|
|
|
// do all exponents bits except the lowest zeros starting from the top
|
|
unsigned int i;
|
|
for (i = e.BitCount() - 1; i>lowest1bit; i--)
|
|
{
|
|
if (e.GetBit(i))
|
|
{
|
|
gfp2.RaiseToPthPower(S[0]);
|
|
gfp2.Accumulate(S[0], gfp2.SpecialOperation2(S[2], c, S[1]));
|
|
S[1] = gfp2.SpecialOperation1(S[1]);
|
|
S[2] = gfp2.SpecialOperation1(S[2]);
|
|
S[0].swap(S[1]);
|
|
}
|
|
else
|
|
{
|
|
gfp2.RaiseToPthPower(S[2]);
|
|
gfp2.Accumulate(S[2], gfp2.SpecialOperation2(S[0], cp, S[1]));
|
|
S[1] = gfp2.SpecialOperation1(S[1]);
|
|
S[0] = gfp2.SpecialOperation1(S[0]);
|
|
S[2].swap(S[1]);
|
|
}
|
|
}
|
|
|
|
// now do the lowest zeros
|
|
while (i--)
|
|
S[1] = gfp2.SpecialOperation1(S[1]);
|
|
|
|
return gfp2.ConvertOut(S[1]);
|
|
}
|
|
|
|
template class AbstractRing<GFP2Element>;
|
|
template class AbstractGroup<GFP2Element>;
|
|
|
|
NAMESPACE_END
|