ssh_string ssh_make_bignum_string(bignum num) {
ssh_string ptr = NULL;
int pad = 0;
unsigned int len = bignum_num_bytes(num);
unsigned int bits = bignum_num_bits(num);
if (len == 0) {
return NULL;
}
/* If the first bit is set we have a negative number */
if (!(bits % 8) && bignum_is_bit_set(num, bits - 1)) {
pad++;
}
#ifdef DEBUG_CRYPTO
fprintf(stderr, "%d bits, %d bytes, %d padding\n", bits, len, pad);
#endif /* DEBUG_CRYPTO */
ptr = ssh_string_new(len + pad);
if (ptr == NULL) {
return NULL;
}
/* We have a negative number so we need a leading zero */
if (pad) {
ptr->data[0] = 0;
}
bignum_bn2bin(num, len, ptr->data + pad);
return ptr;
}
ssh_string make_bignum_string(bignum num) {
ssh_string ptr = NULL;
int pad = 0;
unsigned int len = bignum_num_bytes(num);
unsigned int bits = bignum_num_bits(num);
/* Remember if the fist bit is set, it is considered as a
* negative number. So 0's must be appended */
if (!(bits % 8) && bignum_is_bit_set(num, bits - 1)) {
pad++;
}
#ifdef DEBUG_CRYPTO
fprintf(stderr, "%d bits, %d bytes, %d padding\n", bits, len, pad);
#endif /* DEBUG_CRYPTO */
/* TODO: fix that crap !! */
ptr = malloc(4 + len + pad);
if (ptr == NULL) {
return NULL;
}
ptr->size = htonl(len + pad);
if (pad) {
ptr->string[0] = 0;
}
#ifdef HAVE_LIBGCRYPT
bignum_bn2bin(num, len, ptr->string + pad);
#elif HAVE_LIBCRYPTO
bignum_bn2bin(num, ptr->string + pad);
#endif
return ptr;
}
/** @brief generates a random integer between 0 and max
* @returns 1 in case of success, 0 otherwise
*/
int ssh_gcry_rand_range(bignum dest, bignum max)
{
size_t bits;
bignum rnd;
int rc;
bits = bignum_num_bits(max) + 64;
rnd = bignum_new();
if (rnd == NULL) {
return 0;
}
rc = bignum_rand(rnd, bits);
if (rc != 1) {
return rc;
}
gcry_mpi_mod(dest, rnd, max);
bignum_safe_free(rnd);
return 1;
}
