luc.cpp

// luc.cpp - originally written and placed in the public domain by Wei Dai
 
#include "pch.h"
#include "luc.h"
#include "asn.h"
#include "sha.h"
#include "integer.h"
#include "nbtheory.h"
#include "algparam.h"
#include "pkcspad.h"
 
NAMESPACE_BEGIN(CryptoPP)
 
#if defined(CRYPTOPP_DEBUG) && !defined(CRYPTOPP_DOXYGEN_PROCESSING)
void LUC_TestInstantiations()
{
    LUC_HMP<SHA1>::Signer t1;
    LUCFunction t2;
    InvertibleLUCFunction t3;
}
#endif
 
void DL_Algorithm_LUC_HMP::Sign(const DL_GroupParameters<Integer> &params, const Integer &x, const Integer &k, const Integer &e, Integer &r, Integer &s) const
{
    const Integer &q = params.GetSubgroupOrder();
    r = params.ExponentiateBase(k);
    s = (k + x*(r+e)) % q;
}
 
bool DL_Algorithm_LUC_HMP::Verify(const DL_GroupParameters<Integer> &params, const DL_PublicKey<Integer> &publicKey, const Integer &e, const Integer &r, const Integer &s) const
{
    const Integer p = params.GetGroupOrder()-1;
    const Integer &q = params.GetSubgroupOrder();
 
    Integer Vsg = params.ExponentiateBase(s);
    Integer Vry = publicKey.ExponentiatePublicElement((r+e)%q);
    return (Vsg*Vsg + Vry*Vry + r*r) % p == (Vsg * Vry * r + 4) % p;
}
 
Integer DL_BasePrecomputation_LUC::Exponentiate(const DL_GroupPrecomputation<Element> &group, const Integer &exponent) const
{
    return Lucas(exponent, m_g, static_cast<const DL_GroupPrecomputation_LUC &>(group).GetModulus());
}
 
void DL_GroupParameters_LUC::SimultaneousExponentiate(Element *results, const Element &base, const Integer *exponents, unsigned int exponentsCount) const
{
    for (unsigned int i=0; i<exponentsCount; i++)
        results[i] = Lucas(exponents[i], base, GetModulus());
}
 
void LUCFunction::BERDecode(BufferedTransformation &bt)
{
    BERSequenceDecoder seq(bt);
    m_n.BERDecode(seq);
    m_e.BERDecode(seq);
    seq.MessageEnd();
}
 
void LUCFunction::DEREncode(BufferedTransformation &bt) const
{
    DERSequenceEncoder seq(bt);
    m_n.DEREncode(seq);
    m_e.DEREncode(seq);
    seq.MessageEnd();
}
 
Integer LUCFunction::ApplyFunction(const Integer &x) const
{
    DoQuickSanityCheck();
    return Lucas(m_e, x, m_n);
}
 
bool LUCFunction::Validate(RandomNumberGenerator &rng, unsigned int level) const
{
    CRYPTOPP_UNUSED(rng), CRYPTOPP_UNUSED(level);
    bool pass = true;
    pass = pass && m_n > Integer::One() && m_n.IsOdd();
    CRYPTOPP_ASSERT(pass);
    pass = pass && m_e > Integer::One() && m_e.IsOdd() && m_e < m_n;
    CRYPTOPP_ASSERT(pass);
    return pass;
}
 
bool LUCFunction::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 LUCFunction::AssignFrom(const NameValuePairs &source)
{
    AssignFromHelper(this, source)
        CRYPTOPP_SET_FUNCTION_ENTRY(Modulus)
        CRYPTOPP_SET_FUNCTION_ENTRY(PublicExponent)
        ;
}
 
// *****************************************************************************
// private key operations:
 
class LUCPrimeSelector : public PrimeSelector
{
public:
    LUCPrimeSelector(const Integer &e) : m_e(e) {}
    bool IsAcceptable(const Integer &candidate) const
    {
        return RelativelyPrime(m_e, candidate+1) && RelativelyPrime(m_e, candidate-1);
    }
    Integer m_e;
};
 
void InvertibleLUCFunction::GenerateRandom(RandomNumberGenerator &rng, const NameValuePairs &alg)
{
    int modulusSize = 2048;
    alg.GetIntValue("ModulusSize", modulusSize) || alg.GetIntValue("KeySize", modulusSize);
 
    if (modulusSize < 16)
        throw InvalidArgument("InvertibleLUCFunction: specified modulus size is too small");
 
    m_e = alg.GetValueWithDefault("PublicExponent", Integer(17));
 
    if (m_e < 5 || m_e.IsEven())
        throw InvalidArgument("InvertibleLUCFunction: invalid public exponent");
 
    LUCPrimeSelector selector(m_e);
    AlgorithmParameters primeParam = MakeParametersForTwoPrimesOfEqualSize(modulusSize)
        ("PointerToPrimeSelector", selector.GetSelectorPointer());
    m_p.GenerateRandom(rng, primeParam);
    m_q.GenerateRandom(rng, primeParam);
 
    m_n = m_p * m_q;
    m_u = m_q.InverseMod(m_p);
}
 
void InvertibleLUCFunction::Initialize(RandomNumberGenerator &rng, unsigned int keybits, const Integer &e)
{
    GenerateRandom(rng, MakeParameters("ModulusSize", (int)keybits)("PublicExponent", e));
}
 
void InvertibleLUCFunction::BERDecode(BufferedTransformation &bt)
{
    BERSequenceDecoder seq(bt);
 
    Integer version(seq);
    if (!!version)  // make sure version is 0
        BERDecodeError();
 
    m_n.BERDecode(seq);
    m_e.BERDecode(seq);
    m_p.BERDecode(seq);
    m_q.BERDecode(seq);
    m_u.BERDecode(seq);
    seq.MessageEnd();
}
 
void InvertibleLUCFunction::DEREncode(BufferedTransformation &bt) const
{
    DERSequenceEncoder seq(bt);
 
    const byte version[] = {INTEGER, 1, 0};
    seq.Put(version, sizeof(version));
    m_n.DEREncode(seq);
    m_e.DEREncode(seq);
    m_p.DEREncode(seq);
    m_q.DEREncode(seq);
    m_u.DEREncode(seq);
    seq.MessageEnd();
}
 
Integer InvertibleLUCFunction::CalculateInverse(RandomNumberGenerator &rng, const Integer &x) const
{
    // not clear how to do blinding with LUC
    CRYPTOPP_UNUSED(rng);
    DoQuickSanityCheck();
    return InverseLucas(m_e, x, m_q, m_p, m_u);
}
 
bool InvertibleLUCFunction::Validate(RandomNumberGenerator &rng, unsigned int level) const
{
    bool pass = LUCFunction::Validate(rng, level);
    CRYPTOPP_ASSERT(pass);
    pass = pass && m_p > Integer::One() && m_p.IsOdd() && m_p < m_n;
    CRYPTOPP_ASSERT(pass);
    pass = pass && m_q > Integer::One() && m_q.IsOdd() && m_q < m_n;
    CRYPTOPP_ASSERT(pass);
    pass = pass && m_u.IsPositive() && m_u < m_p;
    CRYPTOPP_ASSERT(pass);
    if (level >= 1)
    {
        pass = pass && m_p * m_q == m_n;
        CRYPTOPP_ASSERT(pass);
        pass = pass && RelativelyPrime(m_e, m_p+1);
        CRYPTOPP_ASSERT(pass);
        pass = pass && RelativelyPrime(m_e, m_p-1);
        CRYPTOPP_ASSERT(pass);
        pass = pass && RelativelyPrime(m_e, m_q+1);
        CRYPTOPP_ASSERT(pass);
        pass = pass && RelativelyPrime(m_e, m_q-1);
        CRYPTOPP_ASSERT(pass);
        pass = pass && m_u * m_q % m_p == 1;
        CRYPTOPP_ASSERT(pass);
    }
    if (level >= 2)
    {
        pass = pass && VerifyPrime(rng, m_p, level-2) && VerifyPrime(rng, m_q, level-2);
        CRYPTOPP_ASSERT(pass);
    }
    return pass;
}
 
bool InvertibleLUCFunction::GetVoidValue(const char *name, const std::type_info &valueType, void *pValue) const
{
    return GetValueHelper<LUCFunction>(this, name, valueType, pValue).Assignable()
        CRYPTOPP_GET_FUNCTION_ENTRY(Prime1)
        CRYPTOPP_GET_FUNCTION_ENTRY(Prime2)
        CRYPTOPP_GET_FUNCTION_ENTRY(MultiplicativeInverseOfPrime2ModPrime1)
        ;
}
 
void InvertibleLUCFunction::AssignFrom(const NameValuePairs &source)
{
    AssignFromHelper<LUCFunction>(this, source)
        CRYPTOPP_SET_FUNCTION_ENTRY(Prime1)
        CRYPTOPP_SET_FUNCTION_ENTRY(Prime2)
        CRYPTOPP_SET_FUNCTION_ENTRY(MultiplicativeInverseOfPrime2ModPrime1)
        ;
}
 
NAMESPACE_END