*
*/
+
+
#include <stdio.h>
#include <time.h>
#include "cryptlib.h"
#include "bn_lcl.h"
#include <openssl/rand.h>
+#include <openssl/sha.h>
static int bnrand(int pseudorand, BIGNUM *rnd, int bits, int top, int bottom)
{
{
return bn_rand_range(1, r, range);
}
+
+#ifndef OPENSSL_NO_SHA512
+/* BN_generate_dsa_nonce generates a random number 0 <= out < range. Unlike
+ * BN_rand_range, it also includes the contents of |priv| and |message| in the
+ * generation so that an RNG failure isn't fatal as long as |priv| remains
+ * secret. This is intended for use in DSA and ECDSA where an RNG weakness
+ * leads directly to private key exposure unless this function is used. */
+int BN_generate_dsa_nonce(BIGNUM *out, const BIGNUM *range, const BIGNUM* priv,
+ const unsigned char *message, size_t message_len,
+ BN_CTX *ctx)
+ {
+ SHA512_CTX sha;
+ /* We use 512 bits of random data per iteration to
+ * ensure that we have at least |range| bits of randomness. */
+ unsigned char random_bytes[64];
+ unsigned char digest[SHA512_DIGEST_LENGTH];
+ unsigned done, todo;
+ /* We generate |range|+8 bytes of random output. */
+ const unsigned num_k_bytes = BN_num_bytes(range) + 8;
+ unsigned char private_bytes[96];
+ unsigned char *k_bytes;
+ int ret = 0;
+
+ k_bytes = OPENSSL_malloc(num_k_bytes);
+ if (!k_bytes)
+ goto err;
+
+ /* We copy |priv| into a local buffer to avoid exposing its length. */
+ todo = sizeof(priv->d[0])*priv->top;
+ if (todo > sizeof(private_bytes))
+ {
+ /* No reasonable DSA or ECDSA key should have a private key
+ * this large and we don't handle this case in order to avoid
+ * leaking the length of the private key. */
+ BNerr(BN_F_BN_GENERATE_DSA_NONCE, BN_R_PRIVATE_KEY_TOO_LARGE);
+ goto err;
+ }
+ memcpy(private_bytes, priv->d, todo);
+ memset(private_bytes + todo, 0, sizeof(private_bytes) - todo);
+
+ for (done = 0; done < num_k_bytes;) {
+ if (RAND_bytes(random_bytes, sizeof(random_bytes)) != 1)
+ goto err;
+ SHA512_Init(&sha);
+ SHA512_Update(&sha, &done, sizeof(done));
+ SHA512_Update(&sha, private_bytes, sizeof(private_bytes));
+ SHA512_Update(&sha, message, message_len);
+ SHA512_Update(&sha, random_bytes, sizeof(random_bytes));
+ SHA512_Final(digest, &sha);
+
+ todo = num_k_bytes - done;
+ if (todo > SHA512_DIGEST_LENGTH)
+ todo = SHA512_DIGEST_LENGTH;
+ memcpy(k_bytes + done, digest, todo);
+ done += todo;
+ }
+
+ if (!BN_bin2bn(k_bytes, num_k_bytes, out))
+ goto err;
+ if (BN_mod(out, out, range, ctx) != 1)
+ goto err;
+ ret = 1;
+
+err:
+ if (k_bytes)
+ OPENSSL_free(k_bytes);
+ return ret;
+ }
+#endif /* OPENSSL_NO_SHA512 */