pqcrypto/crypto_sign/rainbowVc-classic/clean/rainbow.c

/// @file rainbow.c
/// @brief The standard implementations for functions in rainbow.h
///

#include "blas.h"
#include "rainbow.h"
#include "rainbow_blas.h"
#include "rainbow_config.h"
#include "rainbow_keypair.h"
#include "utils_hash.h"
#include "utils_prng.h"
#include <stdint.h>
#include <stdlib.h>
#include <string.h>


#define MAX_ATTEMPT_FRMAT  128
#define _MAX_O  ((_O1>_O2)?_O1:_O2)
#define _MAX_O_BYTE  ((_O1_BYTE>_O2_BYTE)?_O1_BYTE:_O2_BYTE)

int PQCLEAN_RAINBOWVCCLASSIC_CLEAN_rainbow_sign( uint8_t *signature, const sk_t *sk, const uint8_t *_digest ) {
    uint8_t mat_l1[_O1 * _O1_BYTE];
    uint8_t mat_l2[_O2 * _O2_BYTE];
    uint8_t mat_buffer[2 * _MAX_O * _MAX_O_BYTE];

    // setup PRNG
    prng_t prng_sign;
    uint8_t prng_preseed[LEN_SKSEED + _HASH_LEN];
    memcpy( prng_preseed, sk->sk_seed, LEN_SKSEED );
    memcpy( prng_preseed + LEN_SKSEED, _digest, _HASH_LEN );                          // prng_preseed = sk_seed || digest
    uint8_t prng_seed[_HASH_LEN];
    PQCLEAN_RAINBOWVCCLASSIC_CLEAN_hash_msg( prng_seed, _HASH_LEN, prng_preseed, _HASH_LEN + LEN_SKSEED );
    PQCLEAN_RAINBOWVCCLASSIC_CLEAN_prng_set( &prng_sign, prng_seed, _HASH_LEN );                                     // seed = H( sk_seed || digest )
    for (unsigned i = 0; i < LEN_SKSEED + _HASH_LEN; i++) {
        prng_preseed[i] ^= prng_preseed[i];    // clean
    }
    for (unsigned i = 0; i < _HASH_LEN; i++) {
        prng_seed[i] ^= prng_seed[i];    // clean
    }

    // roll vinegars.
    uint8_t vinegar[_V1_BYTE];
    unsigned n_attempt = 0;
    unsigned l1_succ = 0;
    while ( !l1_succ ) {
        if ( MAX_ATTEMPT_FRMAT <= n_attempt ) {
            break;
        }
        PQCLEAN_RAINBOWVCCLASSIC_CLEAN_prng_gen( &prng_sign, vinegar, _V1_BYTE );                         // generating vinegars
        gfmat_prod( mat_l1, sk->l1_F2, _O1 * _O1_BYTE, _V1, vinegar );     // generating the linear equations for layer 1
        l1_succ = gfmat_inv( mat_l1, mat_l1, _O1, mat_buffer );            // check if the linear equation solvable
        n_attempt ++;
    }

    // Given the vinegars, pre-compute variables needed for layer 2
    uint8_t r_l1_F1[_O1_BYTE] = {0};
    uint8_t r_l2_F1[_O2_BYTE] = {0};
    batch_quad_trimat_eval( r_l1_F1, sk->l1_F1, vinegar, _V1, _O1_BYTE );
    batch_quad_trimat_eval( r_l2_F1, sk->l2_F1, vinegar, _V1, _O2_BYTE );
    uint8_t mat_l2_F3[ _O2 * _O2_BYTE];
    uint8_t mat_l2_F2[_O1 * _O2_BYTE];
    gfmat_prod( mat_l2_F3, sk->l2_F3, _O2 * _O2_BYTE, _V1, vinegar );
    gfmat_prod( mat_l2_F2, sk->l2_F2, _O1 * _O2_BYTE, _V1, vinegar );

    // Some local variables.
    uint8_t _z[_PUB_M_BYTE];
    uint8_t y[_PUB_M_BYTE];
    uint8_t *x_v1 = vinegar;
    uint8_t x_o1[_O1_BYTE];
    uint8_t x_o2[_O1_BYTE];

    uint8_t digest_salt[_HASH_LEN + _SALT_BYTE];
    memcpy( digest_salt, _digest, _HASH_LEN );
    uint8_t *salt = digest_salt + _HASH_LEN;

    uint8_t temp_o[_MAX_O_BYTE + 32]  = {0};
    unsigned succ = 0;
    while ( !succ ) {
        if ( MAX_ATTEMPT_FRMAT <= n_attempt ) {
            break;
        }
        // The computation:  H(digest||salt)  -->   z   --S-->   y  --C-map-->   x   --T-->   w

        PQCLEAN_RAINBOWVCCLASSIC_CLEAN_prng_gen( &prng_sign, salt, _SALT_BYTE );                          // roll the salt
        PQCLEAN_RAINBOWVCCLASSIC_CLEAN_hash_msg( _z, _PUB_M_BYTE, digest_salt, _HASH_LEN + _SALT_BYTE );  // H(digest||salt)

        //  y = S^-1 * z
        memcpy(y, _z, _PUB_M_BYTE);                                     // identity part of S
        gfmat_prod(temp_o, sk->s1, _O1_BYTE, _O2, _z + _O1_BYTE);
        gf256v_add(y, temp_o, _O1_BYTE);

        // Central Map:
        // layer 1: calculate x_o1
        memcpy( temp_o, r_l1_F1, _O1_BYTE );
        gf256v_add( temp_o, y, _O1_BYTE );
        gfmat_prod( x_o1, mat_l1, _O1_BYTE, _O1, temp_o );

        // layer 2: calculate x_o2
        PQCLEAN_RAINBOWVCCLASSIC_CLEAN_gf256v_set_zero( temp_o, _O2_BYTE );
        gfmat_prod( temp_o, mat_l2_F2, _O2_BYTE, _O1, x_o1 );               // F2
        batch_quad_trimat_eval( mat_l2, sk->l2_F5, x_o1, _O1, _O2_BYTE );   // F5
        gf256v_add( temp_o, mat_l2, _O2_BYTE );
        gf256v_add( temp_o, r_l2_F1, _O2_BYTE );                        // F1
        gf256v_add( temp_o, y + _O1_BYTE, _O2_BYTE );

        // generate the linear equations of the 2nd layer
        gfmat_prod( mat_l2, sk->l2_F6, _O2 * _O2_BYTE, _O1, x_o1 );     // F6
        gf256v_add( mat_l2, mat_l2_F3, _O2 * _O2_BYTE);                 // F3
        succ = gfmat_inv( mat_l2, mat_l2, _O2, mat_buffer );
        gfmat_prod( x_o2, mat_l2, _O2_BYTE, _O2, temp_o );             // solve l2 eqs

        n_attempt ++;
    };
    //  w = T^-1 * y
    uint8_t w[_PUB_N_BYTE];
    // identity part of T.
    memcpy( w, x_v1, _V1_BYTE );
    memcpy( w + _V1_BYTE, x_o1, _O1_BYTE );
    memcpy( w + _V2_BYTE, x_o2, _O2_BYTE );
    // Computing the t1 part.
    gfmat_prod(y, sk->t1, _V1_BYTE, _O1, x_o1 );
    gf256v_add(w, y, _V1_BYTE );
    // Computing the t4 part.
    gfmat_prod(y, sk->t4, _V1_BYTE, _O2, x_o2 );
    gf256v_add(w, y, _V1_BYTE );
    // Computing the t3 part.
    gfmat_prod(y, sk->t3, _O1_BYTE, _O2, x_o2 );
    gf256v_add(w + _V1_BYTE, y, _O1_BYTE );

    memset( signature, 0, _SIGNATURE_BYTE );    // set the output 0
    // clean
    memset( &prng_sign, 0, sizeof(prng_t) );
    memset( vinegar, 0, _V1_BYTE );
    memset( r_l1_F1, 0, _O1_BYTE );
    memset( r_l2_F1, 0, _O2_BYTE );
    memset( _z, 0, _PUB_M_BYTE );
    memset( y, 0, _PUB_M_BYTE );
    memset( x_o1, 0, _O1_BYTE );
    memset( x_o2, 0, _O2_BYTE );
    memset( temp_o, 0, sizeof(temp_o) );

    // return: copy w and salt to the signature.
    if ( MAX_ATTEMPT_FRMAT <= n_attempt ) {
        return -1;
    }
    gf256v_add( signature, w, _PUB_N_BYTE );
    gf256v_add( signature + _PUB_N_BYTE, salt, _SALT_BYTE );
    return 0;
}

int PQCLEAN_RAINBOWVCCLASSIC_CLEAN_rainbow_verify( const uint8_t *digest, const uint8_t *signature, const pk_t *pk ) {
    unsigned char digest_ck[_PUB_M_BYTE];
    // public_map( digest_ck , pk , signature ); Evaluating the quadratic public polynomials.
    batch_quad_trimat_eval( digest_ck, pk->pk, signature, _PUB_N, _PUB_M_BYTE );

    unsigned char correct[_PUB_M_BYTE];
    unsigned char digest_salt[_HASH_LEN + _SALT_BYTE];
    memcpy( digest_salt, digest, _HASH_LEN );
    memcpy( digest_salt + _HASH_LEN, signature + _PUB_N_BYTE, _SALT_BYTE );
    PQCLEAN_RAINBOWVCCLASSIC_CLEAN_hash_msg( correct, _PUB_M_BYTE, digest_salt, _HASH_LEN + _SALT_BYTE );   // H( digest || salt )

    // check consistancy.
    unsigned char cc = 0;
    for (unsigned i = 0; i < _PUB_M_BYTE; i++) {
        cc |= (digest_ck[i] ^ correct[i]);
    }
    return (0 == cc) ? 0 : -1;
}