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1 files changed, 243 insertions, 0 deletions

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+// rw.cpp - written and placed in the public domain by Wei Dai
+
+#include "pch.h"
+#include "rw.h"
+#include "nbtheory.h"
+#include "asn.h"
+
+NAMESPACE_BEGIN(CryptoPP)
+
+template<> const byte EMSA2DigestDecoration<SHA>::decoration = 0x33;
+template<> const byte EMSA2DigestDecoration<RIPEMD160>::decoration = 0x31;
+
+void EMSA2Pad::Pad(RandomNumberGenerator &, const byte *input, unsigned int inputLen, byte *emsa2Block, unsigned int emsa2BlockLen) const
+{
+	assert (inputLen > 0 && inputLen <= MaxUnpaddedLength(emsa2BlockLen));
+
+	// convert from bit length to byte length
+	emsa2BlockLen++;
+	if (emsa2BlockLen % 8 > 1)
+	{
+		emsa2Block[0] = 0;
+		emsa2Block++;
+	}
+	emsa2BlockLen /= 8;
+
+	emsa2Block[0] = input[0];			// indicate empty or non-empty message
+	memset(emsa2Block+1, 0xbb, emsa2BlockLen-inputLen-2);	// padd with 0xbb
+	emsa2Block[emsa2BlockLen-inputLen-1] = 0xba;	// separator
+	memcpy(emsa2Block+emsa2BlockLen-inputLen, input+1, inputLen-1);
+	emsa2Block[emsa2BlockLen-1] = 0xcc;	// make it congruent to 12 mod 16
+}
+
+DecodingResult EMSA2Pad::Unpad(const byte *emsa2Block, unsigned int emsa2BlockLen, byte *output) const
+{
+	// convert from bit length to byte length
+	emsa2BlockLen++;
+	if (emsa2BlockLen % 8 > 1)
+	{
+		if (emsa2Block[0] != 0)
+			return DecodingResult();
+		emsa2Block++;
+	}
+	emsa2BlockLen /= 8;
+
+	// check last byte
+	if (emsa2Block[emsa2BlockLen-1] != 0xcc)
+		return DecodingResult();
+
+	// skip past the padding until we find the seperator
+	unsigned i=1;
+	while (i<emsa2BlockLen-1 && emsa2Block[i++] != 0xba)
+		if (emsa2Block[i-1] != 0xbb)     // not valid padding
+			return DecodingResult();
+	assert(i==emsa2BlockLen-1 || emsa2Block[i-1]==0xba);
+
+	unsigned int outputLen = emsa2BlockLen - i;
+	output[0] = emsa2Block[0];
+	memcpy (output+1, emsa2Block+i, outputLen-1);
+	return DecodingResult(outputLen);
+}
+
+// *****************************************************************************
+
+template <word r>
+void RWFunction<r>::BERDecode(BufferedTransformation &bt)
+{
+	BERSequenceDecoder seq(bt);
+	m_n.BERDecode(seq);
+	seq.MessageEnd();
+}
+
+template <word r>
+void RWFunction<r>::DEREncode(BufferedTransformation &bt) const
+{
+	DERSequenceEncoder seq(bt);
+	m_n.DEREncode(seq);
+	seq.MessageEnd();
+}
+
+template <word r>
+Integer RWFunction<r>::ApplyFunction(const Integer &in) const
+{
+	DoQuickSanityCheck();
+
+	Integer out = in.Squared()%m_n;
+	const word r2 = r/2;
+	const word r3a = (16 + 5 - r) % 16;	// n%16 could be 5 or 13
+	const word r3b = (16 + 13 - r) % 16;
+	const word r4 = (8 + 5 - r/2) % 8;	// n%8 == 5
+	switch (out % 16)
+	{
+	case r:
+		break;
+	case r2:
+	case r2+8:
+		out <<= 1;
+		break;
+	case r3a:
+	case r3b:
+		out.Negate();
+		out += m_n;
+		break;
+	case r4:
+	case r4+8:
+		out.Negate();
+		out += m_n;
+		out <<= 1;
+		break;
+	default:
+		out = Integer::Zero();
+	}
+	return out;
+}
+
+template <word r>
+bool RWFunction<r>::Validate(RandomNumberGenerator &rng, unsigned int level) const
+{
+	bool pass = true;
+	pass = pass && m_n > Integer::One() && m_n%8 == 5;
+	return pass;
+}
+
+template <word r>
+bool RWFunction<r>::GetVoidValue(const char *name, const std::type_info &valueType, void *pValue) const
+{
+	return GetValueHelper(this, name, valueType, pValue).Assignable()
+		CRYPTOPP_GET_FUNCTION_ENTRY(Modulus)
+		;
+}
+
+template <word r>
+void RWFunction<r>::AssignFrom(const NameValuePairs &source)
+{
+	AssignFromHelper(this, source)
+		CRYPTOPP_SET_FUNCTION_ENTRY(Modulus)
+		;
+}
+
+// *****************************************************************************
+// private key operations:
+
+// generate a random private key
+template <word r>
+void InvertibleRWFunction<r>::GenerateRandom(RandomNumberGenerator &rng, const NameValuePairs &alg)
+{
+	int modulusSize = 2048;
+	alg.GetIntValue("ModulusSize", modulusSize) || alg.GetIntValue("KeySize", modulusSize);
+
+	if (modulusSize < 16)
+		throw InvalidArgument("InvertibleRWFunction: specified modulus length is too small");
+
+	const NameValuePairs &primeParam = MakeParametersForTwoPrimesOfEqualSize(modulusSize);
+	m_p.GenerateRandom(rng, CombinedNameValuePairs(primeParam, MakeParameters("EquivalentTo", 3)("Mod", 8)));
+	m_q.GenerateRandom(rng, CombinedNameValuePairs(primeParam, MakeParameters("EquivalentTo", 7)("Mod", 8)));
+
+	m_n = m_p * m_q;
+	m_u = m_q.InverseMod(m_p);
+}
+
+template <word r>
+void InvertibleRWFunction<r>::BERDecode(BufferedTransformation &bt)
+{
+	BERSequenceDecoder seq(bt);
+	m_n.BERDecode(seq);
+	m_p.BERDecode(seq);
+	m_q.BERDecode(seq);
+	m_u.BERDecode(seq);
+	seq.MessageEnd();
+}
+
+template <word r>
+void InvertibleRWFunction<r>::DEREncode(BufferedTransformation &bt) const
+{
+	DERSequenceEncoder seq(bt);
+	m_n.DEREncode(seq);
+	m_p.DEREncode(seq);
+	m_q.DEREncode(seq);
+	m_u.DEREncode(seq);
+	seq.MessageEnd();
+}
+
+template <word r>
+Integer InvertibleRWFunction<r>::CalculateInverse(const Integer &in) const
+{
+	DoQuickSanityCheck();
+
+	Integer cp=in%m_p, cq=in%m_q;
+
+	if (Jacobi(cp, m_p) * Jacobi(cq, m_q) != 1)
+	{
+		cp = cp%2 ? (cp+m_p) >> 1 : cp >> 1;
+		cq = cq%2 ? (cq+m_q) >> 1 : cq >> 1;
+	}
+
+	cp = ModularSquareRoot(cp, m_p);
+	cq = ModularSquareRoot(cq, m_q);
+
+	Integer out = CRT(cq, m_q, cp, m_p, m_u);
+
+	return STDMIN(out, m_n-out);
+}
+
+template <word r>
+bool InvertibleRWFunction<r>::Validate(RandomNumberGenerator &rng, unsigned int level) const
+{
+	bool pass = RWFunction<r>::Validate(rng, level);
+	pass = pass && m_p > Integer::One() && m_p%8 == 3 && m_p < m_n;
+	pass = pass && m_q > Integer::One() && m_q%8 == 7 && 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;
+	}
+	if (level >= 2)
+		pass = pass && VerifyPrime(rng, m_p, level-2) && VerifyPrime(rng, m_q, level-2);
+	return pass;
+}
+
+template <word r>
+bool InvertibleRWFunction<r>::GetVoidValue(const char *name, const std::type_info &valueType, void *pValue) const
+{
+	return GetValueHelper<RWFunction<r> >(this, name, valueType, pValue).Assignable()
+		CRYPTOPP_GET_FUNCTION_ENTRY(Prime1)
+		CRYPTOPP_GET_FUNCTION_ENTRY(Prime2)
+		CRYPTOPP_GET_FUNCTION_ENTRY(MultiplicativeInverseOfPrime2ModPrime1)
+		;
+}
+
+template <word r>
+void InvertibleRWFunction<r>::AssignFrom(const NameValuePairs &source)
+{
+	AssignFromHelper<RWFunction<r> >(this, source)
+		CRYPTOPP_SET_FUNCTION_ENTRY(Prime1)
+		CRYPTOPP_SET_FUNCTION_ENTRY(Prime2)
+		CRYPTOPP_SET_FUNCTION_ENTRY(MultiplicativeInverseOfPrime2ModPrime1)
+		;
+}
+
+template class RWFunction<IFSSA_R>;
+template class InvertibleRWFunction<IFSSA_R>;
+
+NAMESPACE_END