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// rabin.cpp - written and placed in the public domain by Wei Dai
#include "pch.h"
#include "rabin.h"
#include "nbtheory.h"
#include "asn.h"
#include "sha.h"
#include "modarith.h"
NAMESPACE_BEGIN(CryptoPP)
void RabinFunction::BERDecode(BufferedTransformation &bt)
{
BERSequenceDecoder seq(bt);
m_n.BERDecode(seq);
m_r.BERDecode(seq);
m_s.BERDecode(seq);
seq.MessageEnd();
}
void RabinFunction::DEREncode(BufferedTransformation &bt) const
{
DERSequenceEncoder seq(bt);
m_n.DEREncode(seq);
m_r.DEREncode(seq);
m_s.DEREncode(seq);
seq.MessageEnd();
}
Integer RabinFunction::ApplyFunction(const Integer &in) const
{
DoQuickSanityCheck();
Integer out = in.Squared()%m_n;
if (in.IsOdd())
out = out*m_r%m_n;
if (Jacobi(in, m_n)==-1)
out = out*m_s%m_n;
return out;
}
bool RabinFunction::Validate(RandomNumberGenerator &rng, unsigned int level) const
{
bool pass = true;
pass = pass && m_n > Integer::One() && m_n%4 == 1;
pass = pass && m_r > Integer::One() && m_r < m_n;
pass = pass && m_s > Integer::One() && m_s < m_n;
if (level >= 1)
pass = pass && Jacobi(m_r, m_n) == -1 && Jacobi(m_s, m_n) == -1;
return pass;
}
bool RabinFunction::GetVoidValue(const char *name, const std::type_info &valueType, void *pValue) const
{
return GetValueHelper(this, name, valueType, pValue).Assignable()
CRYPTOPP_GET_FUNCTION_ENTRY(Modulus)
CRYPTOPP_GET_FUNCTION_ENTRY(QuadraticResidueModPrime1)
CRYPTOPP_GET_FUNCTION_ENTRY(QuadraticResidueModPrime2)
;
}
void RabinFunction::AssignFrom(const NameValuePairs &source)
{
AssignFromHelper(this, source)
CRYPTOPP_SET_FUNCTION_ENTRY(Modulus)
CRYPTOPP_SET_FUNCTION_ENTRY(QuadraticResidueModPrime1)
CRYPTOPP_SET_FUNCTION_ENTRY(QuadraticResidueModPrime2)
;
}
// *****************************************************************************
// private key operations:
// generate a random private key
void InvertibleRabinFunction::GenerateRandom(RandomNumberGenerator &rng, const NameValuePairs &alg)
{
int modulusSize = 2048;
alg.GetIntValue("ModulusSize", modulusSize) || alg.GetIntValue("KeySize", modulusSize);
if (modulusSize < 16)
throw InvalidArgument("InvertibleRabinFunction: specified modulus size is too small");
// VC70 workaround: putting these after primeParam causes overlapped stack allocation
bool rFound=false, sFound=false;
Integer t=2;
AlgorithmParameters primeParam = MakeParametersForTwoPrimesOfEqualSize(modulusSize)
("EquivalentTo", 3)("Mod", 4);
m_p.GenerateRandom(rng, primeParam);
m_q.GenerateRandom(rng, primeParam);
while (!(rFound && sFound))
{
int jp = Jacobi(t, m_p);
int jq = Jacobi(t, m_q);
if (!rFound && jp==1 && jq==-1)
{
m_r = t;
rFound = true;
}
if (!sFound && jp==-1 && jq==1)
{
m_s = t;
sFound = true;
}
++t;
}
m_n = m_p * m_q;
m_u = m_q.InverseMod(m_p);
}
void InvertibleRabinFunction::BERDecode(BufferedTransformation &bt)
{
BERSequenceDecoder seq(bt);
m_n.BERDecode(seq);
m_r.BERDecode(seq);
m_s.BERDecode(seq);
m_p.BERDecode(seq);
m_q.BERDecode(seq);
m_u.BERDecode(seq);
seq.MessageEnd();
}
void InvertibleRabinFunction::DEREncode(BufferedTransformation &bt) const
{
DERSequenceEncoder seq(bt);
m_n.DEREncode(seq);
m_r.DEREncode(seq);
m_s.DEREncode(seq);
m_p.DEREncode(seq);
m_q.DEREncode(seq);
m_u.DEREncode(seq);
seq.MessageEnd();
}
Integer InvertibleRabinFunction::CalculateInverse(RandomNumberGenerator &rng, const Integer &in) const
{
DoQuickSanityCheck();
ModularArithmetic modn(m_n);
Integer r(rng, Integer::One(), m_n - Integer::One());
r = modn.Square(r);
Integer r2 = modn.Square(r);
Integer c = modn.Multiply(in, r2); // blind
Integer cp=c%m_p, cq=c%m_q;
int jp = Jacobi(cp, m_p);
int jq = Jacobi(cq, m_q);
if (jq==-1)
{
cp = cp*EuclideanMultiplicativeInverse(m_r, m_p)%m_p;
cq = cq*EuclideanMultiplicativeInverse(m_r, m_q)%m_q;
}
if (jp==-1)
{
cp = cp*EuclideanMultiplicativeInverse(m_s, m_p)%m_p;
cq = cq*EuclideanMultiplicativeInverse(m_s, m_q)%m_q;
}
cp = ModularSquareRoot(cp, m_p);
cq = ModularSquareRoot(cq, m_q);
if (jp==-1)
cp = m_p-cp;
Integer out = CRT(cq, m_q, cp, m_p, m_u);
out = modn.Divide(out, r); // unblind
if ((jq==-1 && out.IsEven()) || (jq==1 && out.IsOdd()))
out = m_n-out;
return out;
}
bool InvertibleRabinFunction::Validate(RandomNumberGenerator &rng, unsigned int level) const
{
bool pass = RabinFunction::Validate(rng, level);
pass = pass && m_p > Integer::One() && m_p%4 == 3 && m_p < m_n;
pass = pass && m_q > Integer::One() && m_q%4 == 3 && m_q < m_n;
pass = pass && m_u.IsPositive() && m_u < m_p;
if (level >= 1)
{
pass = pass && m_p * m_q == m_n;
pass = pass && m_u * m_q % m_p == 1;
pass = pass && Jacobi(m_r, m_p) == 1;
pass = pass && Jacobi(m_r, m_q) == -1;
pass = pass && Jacobi(m_s, m_p) == -1;
pass = pass && Jacobi(m_s, m_q) == 1;
}
if (level >= 2)
pass = pass && VerifyPrime(rng, m_p, level-2) && VerifyPrime(rng, m_q, level-2);
return pass;
}
bool InvertibleRabinFunction::GetVoidValue(const char *name, const std::type_info &valueType, void *pValue) const
{
return GetValueHelper<RabinFunction>(this, name, valueType, pValue).Assignable()
CRYPTOPP_GET_FUNCTION_ENTRY(Prime1)
CRYPTOPP_GET_FUNCTION_ENTRY(Prime2)
CRYPTOPP_GET_FUNCTION_ENTRY(MultiplicativeInverseOfPrime2ModPrime1)
;
}
void InvertibleRabinFunction::AssignFrom(const NameValuePairs &source)
{
AssignFromHelper<RabinFunction>(this, source)
CRYPTOPP_SET_FUNCTION_ENTRY(Prime1)
CRYPTOPP_SET_FUNCTION_ENTRY(Prime2)
CRYPTOPP_SET_FUNCTION_ENTRY(MultiplicativeInverseOfPrime2ModPrime1)
;
}
NAMESPACE_END
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