BGN2/bgn2/src/PrivateKey.cpp

#include "PrivateKey.hpp"

PrivateKey::PrivateKey(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)
{
    set(pub_key, a1, b1, c1, d1, a2, b2, c2, d2);
}

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_curvegen = pi_2(pub_key.get_bipoint_twistgen());
    this->pi_T_curvegen = pi_T(pairing(pub_key.get_bipoint_curvegen(), pub_key.get_bipoint_twistgen()));
}

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

    Bipoint<curvepoint_fp_t> pi_1_ciphertext = pi_1(ciphertext); 

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

    Bipoint<curvepoint_fp_t> 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 Bipoint<twistpoint_fp2_t>& ciphertext)
{
    static std::unordered_map<Bipoint<twistpoint_fp2_t>, Scalar> memoizer;
    static Scalar max_checked = Scalar(0);

    Bipoint<twistpoint_fp2_t> pi_2_ciphertext = pi_2(ciphertext);

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

    Bipoint<twistpoint_fp2_t> 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);
}


void PrivateKey::decrypt(const Quadripoint& ciphertext)
{
    static std::unordered_map<Quadripoint, Scalar> 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_2_ciphertext] = max_checked++;
        i = i + pi_T_pairgen;
    } while (i != pi_T_ciphertext);

    return max_checked - Scalar(1);
}

Bipoint<curvepoint_fp_t> PrivateKey::pi_1(const Bipoint<curvepoint_fp_t>& input) const
{
    Bipoint<curvepoint_fp_t> retval;
    curvepoint_fp_t temp0, temp1;
    

    temp0 = b1 * (c1 * input[0]);
    curvepoint_fp_neg(temp0, temp0);

    temp1 = a1 * (c1 * input[1]);
    curvepoint_fp_add_vartime(temp0, temp0, temp1);
    
    curvepoint_fp_makeaffine(temp0);
    curvepoint_fp_set(retval[0], temp0);


    temp0 = b1 * (d1 * input[0]);
    curvepoint_fp_neg(temp0, temp0);

    temp1 = a1 * (d1 * input[1]);
    curvepoint_fp_add_vartime(temp0, temp0, temp1);
    
    curvepoint_fp_makeaffine(temp0);
    curvepoint_fp_set(retval[1], temp0);


    return retval;
}

Bipoint<twistpoint_fp2_t> PrivateKey::pi_2(const Bipoint<twistpoint_fp2_t>& input) const
{
    Bipoint<twistpoint_fp2_t> retval;
    twistpoint_fp2_t temp0, temp1;
    

    temp0 = b2 * (c2 * input[0]);
    twistpoint_fp2_neg(temp0, temp0);

    temp1 = a2 * (c2 * input[1]);
    twistpoint_fp2_add_vartime(temp0, temp0, temp1);
    
    twistpoint_fp2_makeaffine(temp0);
    twistpoint_fp2_set(retval[0], temp0);


    temp0 = b2 * (d2 * input[0]);
    twistpoint_fp2_neg(temp0, temp0);

    temp1 = a2 * (d2 * input[1]);
    twistpoint_fp2_add_vartime(temp0, temp0, temp1);
    
    twistpoint_fp2_makeaffine(temp0);
    twistpoint_fp2_set(retval[1], temp0);


    return retval;     
}

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


    temp0 = c2 * (b2 * (c1 * (b1 * input[0])));
    
    fp12e_invert(temp1, input[1]);
    temp1 = c2 * (a2 * (c1 * (b1 * temp1)));
    
    fp12e_invert(temp2, input[2]);
    temp2 = c2 * (b2 * (c1 * (a1 * temp2)));
    
    temp3 = c2 * (a2 * (c1 * (a1 * input[3])));

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


    temp0 = d2 * (b2 * (c1 * (b1 * input[0])));
    
    temp1 = b1 * input[0];
    fp12e_invert(temp1, temp1);
    temp1 = d2 * (a2 * (c1 * temp1));

    temp2 = b2 * (c1 * (a1 * input[2]));
    fp12e_invert(temp2, temp2);
    temp2 = d2 * temp2;

    temp3 = d2 * (a2 * (c1 * (a1 * input[3])));

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

    temp0 = c2 * (b2 * (d1 * (b1 * input[0])));
    
    temp1 = b1 * input[0];
    fp12e_invert(temp1, temp1);
    temp1 = c2 * (a2 * (d1 * temp1));

    temp2 = b2 * (d1 * (a1 * input[2]));
    fp12e_invert(temp2, temp2);
    temp2 = c2 * temp2;

    temp3 = c2 * (a2 * (d1 * (a1 * input[3])));
    
    fp12e_mul(temp0, temp0, temp1);
    fp12e_mul(temp1, temp2, temp3);
    fp12e_mul(temp0, temp0, temp1);
    fp12e_set(retval[2], temp0);
    

    temp0 = d2 * (b2 * (d1 * (b1 * input[0])));
    
    temp1 = b1 * input[0];
    fp12e_invert(temp1, temp1);
    temp1 = d2 * (a2 * (d1 * temp1));

    temp2 = b2 * (d1 * (a1 * input[2]));
    fp12e_invert(temp2, temp2);
    temp2 = d2 * temp2;

    temp3 = d2 * (a2 * (d1 * (a1 * input[3])));

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

    return retval;
}