error bignum_mult(bignum *tmp, bignum *r, const bignum *a, const bignum *b)
{
if (r == a || r == b)
{
error err = bignum_mul(tmp, a, b);
if (err)
return err;
return bignum_dup(r, tmp);
}
return bignum_mul(r, a, b);
}
static _rs_inline obj long_mul( INT_64 a, INT_64 b )
{
int am, bm;
if((am = search_one(a))<0 ||
(bm = search_one(b))<0)
return ZERO;
if(am + bm <= 63)
return int_64_compact( int_64_mul(a,b) );
return bignum_mul(int64_to_bignum(a), int64_to_bignum(b));
}
/**
* Algo de karatsuba pour la multiplication de grands entiers
*/
bignum* bignum_mul(bignum a, bignum b) {
int len_a = bignum_len(a);
int len_b = bignum_len(b);
// Multiplication stupide pour les petits nombres
if(len_a < 2 || len_b < 2) {
return bignum_dumb_mul(a, b);
}
int max = MAX(len_a, len_b);
int max_middle = max/2;
bignum* high_a = bignum_init();
bignum* high_b = bignum_init();
bignum* low_a = bignum_init();
bignum* low_b = bignum_init();
bignum_split(a, max-max_middle, high_a, low_a);
bignum_split(b, max-max_middle, high_b, low_b);
bignum* z2 = bignum_mul(*high_a, *high_b);
bignum* z0 = bignum_mul(*low_a, *low_b);
// Je voudrais de l'operator overloading : (z2*10^(max))+((z1-z2-z0)*10^(max_middle))+(z0)
bignum* sum_a = bignum_add(*low_a, *high_a);
bignum* sum_b = bignum_add(*low_b, *high_b);
bignum_destoroyah(high_a);
bignum_destoroyah(high_b);
bignum_destoroyah(low_a);
bignum_destoroyah(low_b);
// z1 = (sum_a*sum_b) - z2 - z0
bignum* mul_of_sum = bignum_mul(*sum_a, *sum_b);
bignum* diff_a = bignum_sub(*mul_of_sum,*z2);
bignum* z1 = bignum_sub(*diff_a, *z0);
bignum_destoroyah(mul_of_sum);
bignum_destoroyah(diff_a);
bignum_destoroyah(sum_a);
bignum_destoroyah(sum_b);
//arrondir pour avoir la bonne puissance de 10 dans les shifts.
float inter = (float)max;
inter = inter/2.0f;
inter += 0.5f;
max_middle = (int) inter;
if(max%2 == 1){
max++;
}
//r1 = z2*10^(max)
bignum* r1 = bignum_copy(z2);
bignum_shift_left(r1, max);
//r2 = z1
bignum* r2 = bignum_copy(z1);
//r2 = r2*10^(max_middle)
bignum_shift_left(r2, max_middle);
//r3 = r2 + z0
bignum* r3 = bignum_add(*r2, *z0);
//bignum_destoroyah(z0);
bignum_destoroyah(r2);
//rf = r1+r3
bignum* rf = bignum_add(*r1, *r3);
bignum_destoroyah(r1);
bignum_destoroyah(r3);
bignum_destoroyah(z0);
bignum_destoroyah(z1);
bignum_destoroyah(z2);
return rf;
}
/**
* crypto_rsa_exptmod - RSA modular exponentiation
* @in: Input data
* @inlen: Input data length
* @out: Buffer for output data
* @outlen: Maximum size of the output buffer and used size on success
* @key: RSA key
* @use_private: 1 = Use RSA private key, 0 = Use RSA public key
* Returns: 0 on success, -1 on failure
*/
int crypto_rsa_exptmod(const u8 *in, size_t inlen, u8 *out, size_t *outlen,
struct crypto_rsa_key *key, int use_private)
{
struct bignum *tmp, *a = NULL, *b = NULL;
int ret = -1;
size_t modlen;
if (use_private && !key->private_key)
return -1;
tmp = bignum_init();
if (tmp == NULL)
return -1;
if (bignum_set_unsigned_bin(tmp, in, inlen) < 0)
goto error;
if (bignum_cmp(key->n, tmp) < 0) {
/* Too large input value for the RSA key modulus */
goto error;
}
if (use_private) {
/*
* Decrypt (or sign) using Chinese remainer theorem to speed
* up calculation. This is equivalent to tmp = tmp^d mod n
* (which would require more CPU to calculate directly).
*
* dmp1 = (1/e) mod (p-1)
* dmq1 = (1/e) mod (q-1)
* iqmp = (1/q) mod p, where p > q
* m1 = c^dmp1 mod p
* m2 = c^dmq1 mod q
* h = q^-1 (m1 - m2) mod p
* m = m2 + hq
*/
a = bignum_init();
b = bignum_init();
if (a == NULL || b == NULL)
goto error;
/* a = tmp^dmp1 mod p */
if (bignum_exptmod(tmp, key->dmp1, key->p, a) < 0)
goto error;
/* b = tmp^dmq1 mod q */
if (bignum_exptmod(tmp, key->dmq1, key->q, b) < 0)
goto error;
/* tmp = (a - b) * (1/q mod p) (mod p) */
if (bignum_sub(a, b, tmp) < 0 ||
bignum_mulmod(tmp, key->iqmp, key->p, tmp) < 0)
goto error;
/* tmp = b + q * tmp */
if (bignum_mul(tmp, key->q, tmp) < 0 ||
bignum_add(tmp, b, tmp) < 0)
goto error;
} else {
/* Encrypt (or verify signature) */
/* tmp = tmp^e mod N */
if (bignum_exptmod(tmp, key->e, key->n, tmp) < 0)
goto error;
}
modlen = crypto_rsa_get_modulus_len(key);
if (modlen > *outlen) {
*outlen = modlen;
goto error;
}
if (bignum_get_unsigned_bin_len(tmp) > modlen)
goto error; /* should never happen */
*outlen = modlen;
os_memset(out, 0, modlen);
if (bignum_get_unsigned_bin(
tmp, out +
(modlen - bignum_get_unsigned_bin_len(tmp)), NULL) < 0)
goto error;
ret = 0;
error:
bignum_deinit(tmp);
bignum_deinit(a);
bignum_deinit(b);
return ret;
}
