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// esign.cpp - written and placed in the public domain by Wei Dai
#include "pch.h"
#include "esign.h"
#include "asn.h"
#include "modarith.h"
#include "nbtheory.h"
#include "sha.h"
#include "algparam.h"
NAMESPACE_BEGIN(CryptoPP)
void ESIGN_TestInstantiations()
{
ESIGN<SHA>::Verifier x1(1, 1);
ESIGN<SHA>::Signer x2(NullRNG(), 1);
ESIGN<SHA>::Verifier x3(x2);
ESIGN<SHA>::Verifier x4(x2.GetKey());
ESIGN<SHA>::Verifier x5(x3);
ESIGN<SHA>::Signer x6 = x2;
x6 = x2;
x3 = ESIGN<SHA>::Verifier(x2);
x4 = x2.GetKey();
}
void ESIGNFunction::BERDecode(BufferedTransformation &bt)
{
BERSequenceDecoder seq(bt);
m_n.BERDecode(seq);
m_e.BERDecode(seq);
seq.MessageEnd();
}
void ESIGNFunction::DEREncode(BufferedTransformation &bt) const
{
DERSequenceEncoder seq(bt);
m_n.DEREncode(seq);
m_e.DEREncode(seq);
seq.MessageEnd();
}
Integer ESIGNFunction::ApplyFunction(const Integer &x) const
{
DoQuickSanityCheck();
return STDMIN(a_exp_b_mod_c(x, m_e, m_n) >> (2*GetK()+2), MaxImage());
}
bool ESIGNFunction::Validate(RandomNumberGenerator &rng, unsigned int level) const
{
bool pass = true;
pass = pass && m_n > Integer::One() && m_n.IsOdd();
pass = pass && m_e >= 8 && m_e < m_n;
return pass;
}
bool ESIGNFunction::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(PublicExponent)
;
}
void ESIGNFunction::AssignFrom(const NameValuePairs &source)
{
AssignFromHelper(this, source)
CRYPTOPP_SET_FUNCTION_ENTRY(Modulus)
CRYPTOPP_SET_FUNCTION_ENTRY(PublicExponent)
;
}
// *****************************************************************************
void InvertibleESIGNFunction::GenerateRandom(RandomNumberGenerator &rng, const NameValuePairs ¶m)
{
int modulusSize = 1023*2;
param.GetIntValue("ModulusSize", modulusSize) || param.GetIntValue("KeySize", modulusSize);
if (modulusSize < 24)
throw InvalidArgument("InvertibleESIGNFunction: specified modulus size is too small");
if (modulusSize % 3 != 0)
throw InvalidArgument("InvertibleESIGNFunction: modulus size must be divisible by 3");
m_e = param.GetValueWithDefault("PublicExponent", Integer(32));
if (m_e < 8)
throw InvalidArgument("InvertibleESIGNFunction: public exponents less than 8 may not be secure");
// VC70 workaround: putting these after primeParam causes overlapped stack allocation
ConstByteArrayParameter seedParam;
SecByteBlock seed;
const Integer minP = Integer(204) << (modulusSize/3-8);
const Integer maxP = Integer::Power2(modulusSize/3)-1;
AlgorithmParameters primeParam = MakeParameters("Min", minP)("Max", maxP)("RandomNumberType", Integer::PRIME);
if (param.GetValue("Seed", seedParam))
{
seed.resize(seedParam.size() + 4);
memcpy(seed + 4, seedParam.begin(), seedParam.size());
PutWord(false, BIG_ENDIAN_ORDER, seed, (word32)0);
m_p.GenerateRandom(rng, CombinedNameValuePairs(primeParam, MakeParameters("Seed", ConstByteArrayParameter(seed))));
PutWord(false, BIG_ENDIAN_ORDER, seed, (word32)1);
m_q.GenerateRandom(rng, CombinedNameValuePairs(primeParam, MakeParameters("Seed", ConstByteArrayParameter(seed))));
}
else
{
m_p.GenerateRandom(rng, primeParam);
m_q.GenerateRandom(rng, primeParam);
}
m_n = m_p * m_p * m_q;
assert(m_n.BitCount() == modulusSize);
}
void InvertibleESIGNFunction::BERDecode(BufferedTransformation &bt)
{
BERSequenceDecoder privateKey(bt);
m_n.BERDecode(privateKey);
m_e.BERDecode(privateKey);
m_p.BERDecode(privateKey);
m_q.BERDecode(privateKey);
privateKey.MessageEnd();
}
void InvertibleESIGNFunction::DEREncode(BufferedTransformation &bt) const
{
DERSequenceEncoder privateKey(bt);
m_n.DEREncode(privateKey);
m_e.DEREncode(privateKey);
m_p.DEREncode(privateKey);
m_q.DEREncode(privateKey);
privateKey.MessageEnd();
}
Integer InvertibleESIGNFunction::CalculateRandomizedInverse(RandomNumberGenerator &rng, const Integer &x) const
{
DoQuickSanityCheck();
Integer pq = m_p * m_q;
Integer p2 = m_p * m_p;
Integer r, z, re, a, w0, w1;
do
{
r.Randomize(rng, Integer::Zero(), pq);
z = x << (2*GetK()+2);
re = a_exp_b_mod_c(r, m_e, m_n);
a = (z - re) % m_n;
Integer::Divide(w1, w0, a, pq);
if (w1.NotZero())
{
++w0;
w1 = pq - w1;
}
}
while ((w1 >> 2*GetK()+1).IsPositive());
ModularArithmetic modp(m_p);
Integer t = modp.Divide(w0 * r % m_p, m_e * re % m_p);
Integer s = r + t*pq;
assert(s < m_n);
/*
using namespace std;
cout << "f = " << x << endl;
cout << "r = " << r << endl;
cout << "z = " << z << endl;
cout << "a = " << a << endl;
cout << "w0 = " << w0 << endl;
cout << "w1 = " << w1 << endl;
cout << "t = " << t << endl;
cout << "s = " << s << endl;
*/
return s;
}
bool InvertibleESIGNFunction::Validate(RandomNumberGenerator &rng, unsigned int level) const
{
bool pass = ESIGNFunction::Validate(rng, level);
pass = pass && m_p > Integer::One() && m_p.IsOdd() && m_p < m_n;
pass = pass && m_q > Integer::One() && m_q.IsOdd() && m_q < m_n;
pass = pass && m_p.BitCount() == m_q.BitCount();
if (level >= 1)
pass = pass && m_p * m_p * m_q == m_n;
if (level >= 2)
pass = pass && VerifyPrime(rng, m_p, level-2) && VerifyPrime(rng, m_q, level-2);
return pass;
}
bool InvertibleESIGNFunction::GetVoidValue(const char *name, const std::type_info &valueType, void *pValue) const
{
return GetValueHelper<ESIGNFunction>(this, name, valueType, pValue).Assignable()
CRYPTOPP_GET_FUNCTION_ENTRY(Prime1)
CRYPTOPP_GET_FUNCTION_ENTRY(Prime2)
;
}
void InvertibleESIGNFunction::AssignFrom(const NameValuePairs &source)
{
AssignFromHelper<ESIGNFunction>(this, source)
CRYPTOPP_SET_FUNCTION_ENTRY(Prime1)
CRYPTOPP_SET_FUNCTION_ENTRY(Prime2)
;
}
NAMESPACE_END
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