BGN2/bgn2/src/PrivateKey.cpp

#include "PrivateKey.hpp"

Scalar PrivateKey::decrypt(const CurveBipoint& ciphertext) const
{
    static std::unordered_map<CurveBipoint, Scalar, CurveBipointHash> memoizer;
    static Scalar max_checked = Scalar(0);

    CurveBipoint pi_1_ciphertext = pi_1(ciphertext); 

    auto lookup = memoizer.find(pi_1_ciphertext);
    if (lookup != memoizer.end())
    {
        return lookup->second;
    }

    CurveBipoint i = pi_1_curvegen * max_checked;
    do
    {
        memoizer[pi_1_ciphertext] = max_checked++;
        i = i + pi_1_curvegen;
    } while (i != pi_1_ciphertext);

    return max_checked - Scalar(1);
}

Scalar PrivateKey::decrypt(const TwistBipoint& ciphertext) const
{
    static std::unordered_map<TwistBipoint, Scalar, TwistBipointHash> memoizer;
    static Scalar max_checked = Scalar(0);

    TwistBipoint pi_2_ciphertext = pi_2(ciphertext);

    auto lookup = memoizer.find(pi_2_ciphertext);
    if (lookup != memoizer.end())
    {
        return lookup->second;
    }

    TwistBipoint i = pi_2_twistgen * max_checked;
    do
    {
        memoizer[pi_2_ciphertext] = max_checked++;
        i = i + pi_2_twistgen;
    } while (i != pi_2_ciphertext);

    return max_checked - Scalar(1);
}


Scalar PrivateKey::decrypt(const Quadripoint& ciphertext) const
{
    static std::unordered_map<Quadripoint, Scalar, QuadripointHash> memoizer;
    static Scalar max_checked = Scalar(0);

    Quadripoint pi_T_ciphertext = pi_T(ciphertext); 

    auto lookup = memoizer.find(pi_T_ciphertext);
    if (lookup != memoizer.end())
    {
        return lookup->second;
    }

    Quadripoint i = pi_T_pairgen * max_checked;
    do
    {
        memoizer[pi_T_ciphertext] = max_checked++;
        i = i + pi_T_pairgen;
    } while (i != pi_T_ciphertext);

    return max_checked - Scalar(1);
}

PrivateKey::PrivateKey()
{ }

void PrivateKey::set(const PublicKey& pub_key, const Scalar& a1, const Scalar& b1, const Scalar& c1, const Scalar& d1, const Scalar& a2, const Scalar& b2, const Scalar& c2, const Scalar& d2)
{
    this->a1 = a1;
    this->b1 = b1;
    this->c1 = c1;
    this->d1 = d1;

    this->a2 = a2;
    this->b2 = b2;
    this->c2 = c2;
    this->d2 = d2;

    this->pi_1_curvegen = pi_1(pub_key.get_bipoint_curvegen());
    this->pi_2_twistgen = pi_2(pub_key.get_bipoint_twistgen());
    this->pi_T_pairgen  = pi_T(pairing(pub_key.get_bipoint_curvegen(), pub_key.get_bipoint_twistgen()));
}

CurveBipoint PrivateKey::pi_1(const CurveBipoint& input) const
{
    CurveBipoint retval;
    curvepoint_fp_t temp0, temp1;
    

    b1.mult(temp0, input[0]);
    c1.mult(temp0, temp0);
    curvepoint_fp_neg(temp0, temp0);

    a1.mult(temp1, input[1]);
    c1.mult(temp1, temp1);

    curvepoint_fp_add_vartime(temp0, temp0, temp1);
    curvepoint_fp_set(retval[0], temp0);


    b1.mult(temp0, input[0]);
    d1.mult(temp0, temp0);
    curvepoint_fp_neg(temp0, temp0);

    a1.mult(temp1, input[1]);
    d1.mult(temp1, temp1);

    curvepoint_fp_add_vartime(temp0, temp0, temp1);
    curvepoint_fp_set(retval[1], temp0);


    return retval;
}

TwistBipoint PrivateKey::pi_2(const TwistBipoint& input) const
{
    TwistBipoint retval;
    twistpoint_fp2_t temp0, temp1;
    

    b2.mult(temp0, input[0]);
    c2.mult(temp0, temp0);
    twistpoint_fp2_neg(temp0, temp0);

    a2.mult(temp1, input[1]);
    c2.mult(temp1, temp1);

    twistpoint_fp2_add_vartime(temp0, temp0, temp1);
    twistpoint_fp2_set(retval[0], temp0);


    b2.mult(temp0, input[0]);
    d2.mult(temp0, temp0);
    twistpoint_fp2_neg(temp0, temp0);

    a2.mult(temp1, input[1]);
    d2.mult(temp1, temp1);

    twistpoint_fp2_add_vartime(temp0, temp0, temp1);
    twistpoint_fp2_set(retval[1], temp0);


    return retval;     
}

Quadripoint PrivateKey::pi_T(const Quadripoint& input) const
{
    Quadripoint retval;
    fp12e_t temp0, temp1, temp2, temp3;


    b1.mult(temp0, input[0]);
    c1.mult(temp0, temp0);
    b2.mult(temp0, temp0);
    c2.mult(temp0, temp0);
    
    b1.mult(temp1, input[1]);
    c1.mult(temp1, temp1);
    a2.mult(temp1, temp1);
    c2.mult(temp1, temp1);
    fp12e_invert(temp1, temp1);

    a1.mult(temp2, input[2]);
    c1.mult(temp2, temp2);
    b2.mult(temp2, temp2);
    c2.mult(temp2, temp2);
    fp12e_invert(temp2, temp2);
    
    a1.mult(temp3, input[3]);
    c1.mult(temp3, temp3);
    a2.mult(temp3, temp3);
    c2.mult(temp3, temp3);

    fp12e_mul(temp0, temp0, temp1);
    fp12e_mul(temp1, temp2, temp3);
    fp12e_mul(temp0, temp0, temp1);
    fp12e_set(retval[0], temp0);


    b1.mult(temp0, input[0]);
    c1.mult(temp0, temp0);
    b2.mult(temp0, temp0);
    d2.mult(temp0, temp0);
    
    b1.mult(temp1, input[1]);
    c1.mult(temp1, temp1);
    a2.mult(temp1, temp1);
    d2.mult(temp1, temp1);
    fp12e_invert(temp1, temp1);

    a1.mult(temp2, input[2]);
    c1.mult(temp2, temp2);
    b2.mult(temp2, temp2);
    d2.mult(temp2, temp2);
    fp12e_invert(temp2, temp2);
    
    a1.mult(temp3, input[3]);
    c1.mult(temp3, temp3);
    a2.mult(temp3, temp3);
    d2.mult(temp3, temp3);

    fp12e_mul(temp0, temp0, temp1);
    fp12e_mul(temp1, temp2, temp3);
    fp12e_mul(temp0, temp0, temp1);
    fp12e_set(retval[1], temp0);
    

    b1.mult(temp0, input[0]);
    d1.mult(temp0, temp0);
    b2.mult(temp0, temp0);
    c2.mult(temp0, temp0);
    
    b1.mult(temp1, input[1]);
    d1.mult(temp1, temp1);
    a2.mult(temp1, temp1);
    c2.mult(temp1, temp1);
    fp12e_invert(temp1, temp1);

    a1.mult(temp2, input[2]);
    d1.mult(temp2, temp2);
    b2.mult(temp2, temp2);
    c2.mult(temp2, temp2);
    fp12e_invert(temp2, temp2);
    
    a1.mult(temp3, input[3]);
    d1.mult(temp3, temp3);
    a2.mult(temp3, temp3);
    c2.mult(temp3, temp3);
    
    fp12e_mul(temp0, temp0, temp1);
    fp12e_mul(temp1, temp2, temp3);
    fp12e_mul(temp0, temp0, temp1);
    fp12e_set(retval[2], temp0);
    

    b1.mult(temp0, input[0]);
    d1.mult(temp0, temp0);
    b2.mult(temp0, temp0);
    d2.mult(temp0, temp0);
    
    b1.mult(temp1, input[1]);
    d1.mult(temp1, temp1);
    a2.mult(temp1, temp1);
    d2.mult(temp1, temp1);
    fp12e_invert(temp1, temp1);

    a1.mult(temp2, input[2]);
    d1.mult(temp2, temp2);
    b2.mult(temp2, temp2);
    d2.mult(temp2, temp2);
    fp12e_invert(temp2, temp2);
    
    a1.mult(temp3, input[3]);
    d1.mult(temp3, temp3);
    a2.mult(temp3, temp3);
    d2.mult(temp3, temp3);

    fp12e_mul(temp0, temp0, temp1);
    fp12e_mul(temp1, temp2, temp3);
    fp12e_mul(temp0, temp0, temp1);
    fp12e_set(retval[3], temp0);
    

    return retval;
}