pqcrypto/crypto_sign/rainbowIIIc-cyclic/clean/rainbow_keypair.c

/// @file rainbow_keypair.c
/// @brief implementations of functions in rainbow_keypair.h
///

#include "rainbow_keypair.h"
#include "blas.h"
#include "blas_comm.h"
#include "rainbow_blas.h"
#include "rainbow_keypair_computation.h"
#include "utils_prng.h"
#include <stdint.h>
#include <stdlib.h>
#include <string.h>

static void generate_S_T(unsigned char *s_and_t, prng_t *prng0) {
    PQCLEAN_RAINBOWIIICCYCLIC_CLEAN_prng_gen(prng0, s_and_t, _O1_BYTE * _O2); // S1
    s_and_t += _O1_BYTE * _O2;
    PQCLEAN_RAINBOWIIICCYCLIC_CLEAN_prng_gen(prng0, s_and_t, _V1_BYTE * _O1); // T1
    s_and_t += _V1_BYTE * _O1;
    PQCLEAN_RAINBOWIIICCYCLIC_CLEAN_prng_gen(prng0, s_and_t, _V1_BYTE * _O2); // T2
    s_and_t += _V1_BYTE * _O2;
    PQCLEAN_RAINBOWIIICCYCLIC_CLEAN_prng_gen(prng0, s_and_t, _O1_BYTE * _O2); // T3
}

static unsigned int generate_l1_F12(unsigned char *sk, prng_t *prng0) {
    unsigned int n_byte_generated = 0;
    PQCLEAN_RAINBOWIIICCYCLIC_CLEAN_prng_gen(prng0, sk, _O1_BYTE * N_TRIANGLE_TERMS(_V1)); // l1_F1
    sk += _O1_BYTE * N_TRIANGLE_TERMS(_V1);
    n_byte_generated += _O1_BYTE * N_TRIANGLE_TERMS(_V1);

    PQCLEAN_RAINBOWIIICCYCLIC_CLEAN_prng_gen(prng0, sk, _O1_BYTE * _V1 * _O1); // l1_F2
    n_byte_generated += _O1_BYTE * _V1 * _O1;
    return n_byte_generated;
}

static unsigned int generate_l2_F12356(unsigned char *sk, prng_t *prng0) {
    unsigned int n_byte_generated = 0;

    PQCLEAN_RAINBOWIIICCYCLIC_CLEAN_prng_gen(prng0, sk, _O2_BYTE * N_TRIANGLE_TERMS(_V1)); // l2_F1
    sk += _O2_BYTE * N_TRIANGLE_TERMS(_V1);
    n_byte_generated += _O2_BYTE * N_TRIANGLE_TERMS(_V1);

    PQCLEAN_RAINBOWIIICCYCLIC_CLEAN_prng_gen(prng0, sk, _O2_BYTE * _V1 * _O1); // l2_F2
    sk += _O2_BYTE * _V1 * _O1;
    n_byte_generated += _O2_BYTE * _V1 * _O1;

    PQCLEAN_RAINBOWIIICCYCLIC_CLEAN_prng_gen(prng0, sk, _O2_BYTE * _V1 * _O2); // l2_F3
    sk += _O2_BYTE * _V1 * _O1;
    n_byte_generated += _O2_BYTE * _V1 * _O1;

    PQCLEAN_RAINBOWIIICCYCLIC_CLEAN_prng_gen(prng0, sk, _O2_BYTE * N_TRIANGLE_TERMS(_O1)); // l2_F5
    sk += _O2_BYTE * N_TRIANGLE_TERMS(_O1);
    n_byte_generated += _O2_BYTE * N_TRIANGLE_TERMS(_O1);

    PQCLEAN_RAINBOWIIICCYCLIC_CLEAN_prng_gen(prng0, sk, _O2_BYTE * _O1 * _O2); // l2_F6
    n_byte_generated += _O2_BYTE * _O1 * _O2;

    return n_byte_generated;
}

static void generate_B1_B2(unsigned char *sk, prng_t *prng0) {
    sk += generate_l1_F12(sk, prng0);
    generate_l2_F12356(sk, prng0);
}

static void calculate_t4(unsigned char *t2_to_t4, const unsigned char *t1, const unsigned char *t3) {
    //  t4 = T_sk.t1 * T_sk.t3 - T_sk.t2
    unsigned char temp[_V1_BYTE + 32];
    unsigned char *t4 = t2_to_t4;
    for (unsigned int i = 0; i < _O2; i++) { /// t3 width
        gfmat_prod(temp, t1, _V1_BYTE, _O1, t3);
        PQCLEAN_RAINBOWIIICCYCLIC_CLEAN_gf256v_add(t4, temp, _V1_BYTE);
        t4 += _V1_BYTE;
        t3 += _O1_BYTE;
    }
}

static void obsfucate_l1_polys(unsigned char *l1_polys, const unsigned char *l2_polys, unsigned int n_terms, const unsigned char *s1) {
    unsigned char temp[_O1_BYTE + 32];
    while (n_terms--) {
        gfmat_prod(temp, s1, _O1_BYTE, _O2, l2_polys);
        PQCLEAN_RAINBOWIIICCYCLIC_CLEAN_gf256v_add(l1_polys, temp, _O1_BYTE);
        l1_polys += _O1_BYTE;
        l2_polys += _O2_BYTE;
    }
}

///////////////////  Classic //////////////////////////////////


/////////////////////   Cyclic   //////////////////////////////////
void PQCLEAN_RAINBOWIIICCYCLIC_CLEAN_generate_keypair_cyclic(cpk_t *pk, sk_t *sk, const unsigned char *pk_seed, const unsigned char *sk_seed) {
    memcpy(pk->pk_seed, pk_seed, LEN_PKSEED);
    memcpy(sk->sk_seed, sk_seed, LEN_SKSEED);

    // prng for sk
    prng_t prng;
    prng_t *prng0 = &prng;
    PQCLEAN_RAINBOWIIICCYCLIC_CLEAN_prng_set(prng0, sk_seed, LEN_SKSEED);
    generate_S_T(sk->s1, prng0); // S,T:  only a part of sk

    unsigned char t2[sizeof(sk->t4)];
    memcpy(t2, sk->t4, _V1_BYTE * _O2);   // temporarily store t2
    calculate_t4(sk->t4, sk->t1, sk->t3); // t2 <- t4

    // prng for pk
    sk_t inst_Qs;
    sk_t *Qs = &inst_Qs;
    prng_t *prng1 = &prng;
    PQCLEAN_RAINBOWIIICCYCLIC_CLEAN_prng_set(prng1, pk_seed, LEN_PKSEED);
    generate_B1_B2(Qs->l1_F1, prng1); // generating l1_Q1, l1_Q2, l2_Q1, l2_Q2, l2_Q3, l2_Q5, l2_Q6
    obsfucate_l1_polys(Qs->l1_F1, Qs->l2_F1, N_TRIANGLE_TERMS(_V1), sk->s1);
    obsfucate_l1_polys(Qs->l1_F2, Qs->l2_F2, _V1 * _O1, sk->s1);
    // so far, the Qs contains l1_F1, l1_F2, l2_F1, l2_F2, l2_F3, l2_F5, l2_F6.

    PQCLEAN_RAINBOWIIICCYCLIC_CLEAN_calculate_F_from_Q(sk, Qs, sk); // calcuate the rest parts of secret key from Qs and S,T

    unsigned char t4[sizeof(sk->t4)];
    memcpy(t4, sk->t4, _V1_BYTE * _O2);                      // temporarily store t4
    memcpy(sk->t4, t2, _V1_BYTE * _O2);                      // restore t2
    PQCLEAN_RAINBOWIIICCYCLIC_CLEAN_calculate_Q_from_F_cyclic(pk, sk, sk); // calculate the rest parts of public key: l1_Q3, l1_Q5, l1_Q6, l1_Q9, l2_Q9
    memcpy(sk->t4, t4, _V1_BYTE * _O2);                      // restore t4

    obsfucate_l1_polys(pk->l1_Q3, Qs->l2_F3, _V1 * _O2, sk->s1);
    obsfucate_l1_polys(pk->l1_Q5, Qs->l2_F5, N_TRIANGLE_TERMS(_O1), sk->s1);
    obsfucate_l1_polys(pk->l1_Q6, Qs->l2_F6, _O1 * _O2, sk->s1);
    obsfucate_l1_polys(pk->l1_Q9, pk->l2_Q9, N_TRIANGLE_TERMS(_O2), sk->s1);

    // clean
    memset(&prng, 0, sizeof(prng_t));
}



void PQCLEAN_RAINBOWIIICCYCLIC_CLEAN_cpk_to_pk(pk_t *rpk, const cpk_t *cpk) {
    // procedure:  cpk_t --> extcpk_t  --> pk_t

    // convert from cpk_t to extcpk_t
    ext_cpk_t pk;

    // setup prng
    prng_t prng0;
    PQCLEAN_RAINBOWIIICCYCLIC_CLEAN_prng_set(&prng0, cpk->pk_seed, LEN_SKSEED);

    // generating parts of key with prng
    generate_l1_F12(pk.l1_Q1, &prng0);
    // copying parts of key from input. l1_Q3, l1_Q5, l1_Q6, l1_Q9
    memcpy(pk.l1_Q3, cpk->l1_Q3, _O1_BYTE * (_V1 * _O2 + N_TRIANGLE_TERMS(_O1) + _O1 * _O2 + N_TRIANGLE_TERMS(_O2)));

    // generating parts of key with prng
    generate_l2_F12356(pk.l2_Q1, &prng0);
    // copying parts of key from input: l2_Q9
    memcpy(pk.l2_Q9, cpk->l2_Q9, _O2_BYTE * N_TRIANGLE_TERMS(_O2));

    // convert from extcpk_t to pk_t
    PQCLEAN_RAINBOWIIICCYCLIC_CLEAN_extcpk_to_pk(rpk, &pk);
}