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197 lines
5.0 KiB
197 lines
5.0 KiB
![]()
4 years ago
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// rw.cpp - written and placed in the public domain by Wei Dai
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#include "pch.h"
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#include "rw.h"
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#include "nbtheory.h"
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#include "asn.h"
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#ifndef CRYPTOPP_IMPORTS
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NAMESPACE_BEGIN(CryptoPP)
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void RWFunction::BERDecode(BufferedTransformation &bt)
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{
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BERSequenceDecoder seq(bt);
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m_n.BERDecode(seq);
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seq.MessageEnd();
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}
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void RWFunction::DEREncode(BufferedTransformation &bt) const
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{
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DERSequenceEncoder seq(bt);
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m_n.DEREncode(seq);
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seq.MessageEnd();
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}
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Integer RWFunction::ApplyFunction(const Integer &in) const
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{
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DoQuickSanityCheck();
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Integer out = in.Squared()%m_n;
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const word r = 12;
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// this code was written to handle both r = 6 and r = 12,
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// but now only r = 12 is used in P1363
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const word r2 = r/2;
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const word r3a = (16 + 5 - r) % 16; // n%16 could be 5 or 13
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const word r3b = (16 + 13 - r) % 16;
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const word r4 = (8 + 5 - r/2) % 8; // n%8 == 5
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switch (out % 16)
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{
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case r:
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break;
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case r2:
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case r2+8:
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out <<= 1;
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break;
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case r3a:
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case r3b:
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out.Negate();
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out += m_n;
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break;
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case r4:
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case r4+8:
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out.Negate();
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out += m_n;
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out <<= 1;
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break;
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default:
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out = Integer::Zero();
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}
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return out;
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}
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bool RWFunction::Validate(RandomNumberGenerator &rng, unsigned int level) const
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{
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bool pass = true;
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pass = pass && m_n > Integer::One() && m_n%8 == 5;
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return pass;
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}
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bool RWFunction::GetVoidValue(const char *name, const std::type_info &valueType, void *pValue) const
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{
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return GetValueHelper(this, name, valueType, pValue).Assignable()
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CRYPTOPP_GET_FUNCTION_ENTRY(Modulus)
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;
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}
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void RWFunction::AssignFrom(const NameValuePairs &source)
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{
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AssignFromHelper(this, source)
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CRYPTOPP_SET_FUNCTION_ENTRY(Modulus)
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;
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}
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// *****************************************************************************
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// private key operations:
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// generate a random private key
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void InvertibleRWFunction::GenerateRandom(RandomNumberGenerator &rng, const NameValuePairs &alg)
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{
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int modulusSize = 2048;
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alg.GetIntValue("ModulusSize", modulusSize) || alg.GetIntValue("KeySize", modulusSize);
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if (modulusSize < 16)
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throw InvalidArgument("InvertibleRWFunction: specified modulus length is too small");
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AlgorithmParameters primeParam = MakeParametersForTwoPrimesOfEqualSize(modulusSize);
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m_p.GenerateRandom(rng, CombinedNameValuePairs(primeParam, MakeParameters("EquivalentTo", 3)("Mod", 8)));
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m_q.GenerateRandom(rng, CombinedNameValuePairs(primeParam, MakeParameters("EquivalentTo", 7)("Mod", 8)));
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m_n = m_p * m_q;
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m_u = m_q.InverseMod(m_p);
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}
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void InvertibleRWFunction::BERDecode(BufferedTransformation &bt)
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{
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BERSequenceDecoder seq(bt);
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m_n.BERDecode(seq);
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m_p.BERDecode(seq);
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m_q.BERDecode(seq);
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m_u.BERDecode(seq);
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seq.MessageEnd();
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}
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void InvertibleRWFunction::DEREncode(BufferedTransformation &bt) const
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{
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DERSequenceEncoder seq(bt);
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m_n.DEREncode(seq);
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m_p.DEREncode(seq);
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m_q.DEREncode(seq);
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m_u.DEREncode(seq);
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seq.MessageEnd();
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}
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Integer InvertibleRWFunction::CalculateInverse(RandomNumberGenerator &rng, const Integer &x) const
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{
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DoQuickSanityCheck();
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ModularArithmetic modn(m_n);
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Integer r, rInv;
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do { // do this in a loop for people using small numbers for testing
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r.Randomize(rng, Integer::One(), m_n - Integer::One());
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rInv = modn.MultiplicativeInverse(r);
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} while (rInv.IsZero());
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Integer re = modn.Square(r);
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re = modn.Multiply(re, x); // blind
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Integer cp=re%m_p, cq=re%m_q;
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if (Jacobi(cp, m_p) * Jacobi(cq, m_q) != 1)
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{
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cp = cp.IsOdd() ? (cp+m_p) >> 1 : cp >> 1;
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cq = cq.IsOdd() ? (cq+m_q) >> 1 : cq >> 1;
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}
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#pragma omp parallel
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#pragma omp sections
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{
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#pragma omp section
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cp = ModularSquareRoot(cp, m_p);
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#pragma omp section
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cq = ModularSquareRoot(cq, m_q);
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}
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Integer y = CRT(cq, m_q, cp, m_p, m_u);
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y = modn.Multiply(y, rInv); // unblind
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y = STDMIN(y, m_n-y);
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if (ApplyFunction(y) != x) // check
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throw Exception(Exception::OTHER_ERROR, "InvertibleRWFunction: computational error during private key operation");
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return y;
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}
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bool InvertibleRWFunction::Validate(RandomNumberGenerator &rng, unsigned int level) const
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{
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bool pass = RWFunction::Validate(rng, level);
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pass = pass && m_p > Integer::One() && m_p%8 == 3 && m_p < m_n;
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pass = pass && m_q > Integer::One() && m_q%8 == 7 && m_q < m_n;
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pass = pass && m_u.IsPositive() && m_u < m_p;
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if (level >= 1)
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{
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pass = pass && m_p * m_q == m_n;
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pass = pass && m_u * m_q % m_p == 1;
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}
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if (level >= 2)
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pass = pass && VerifyPrime(rng, m_p, level-2) && VerifyPrime(rng, m_q, level-2);
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return pass;
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}
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bool InvertibleRWFunction::GetVoidValue(const char *name, const std::type_info &valueType, void *pValue) const
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{
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return GetValueHelper<RWFunction>(this, name, valueType, pValue).Assignable()
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CRYPTOPP_GET_FUNCTION_ENTRY(Prime1)
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CRYPTOPP_GET_FUNCTION_ENTRY(Prime2)
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CRYPTOPP_GET_FUNCTION_ENTRY(MultiplicativeInverseOfPrime2ModPrime1)
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;
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}
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void InvertibleRWFunction::AssignFrom(const NameValuePairs &source)
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{
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AssignFromHelper<RWFunction>(this, source)
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CRYPTOPP_SET_FUNCTION_ENTRY(Prime1)
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CRYPTOPP_SET_FUNCTION_ENTRY(Prime2)
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CRYPTOPP_SET_FUNCTION_ENTRY(MultiplicativeInverseOfPrime2ModPrime1)
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;
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}
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NAMESPACE_END
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#endif
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