[GNUnet-SVN] r32073 - gnunet/src/util

[gnunet]

Author: cfuchs
Date: 2014-01-29 15:34:33 +0100 (Wed, 29 Jan 2014)
New Revision: 32073

Modified:
   gnunet/src/util/crypto_paillier.c
   gnunet/src/util/test_crypto_paillier.c
Log:
- formatting
- forgot to reduce the possible homomorphic opts by one, as a badly chosen n 
might sometimes corrupt the final operation using a simple check. As the 
overall calculation of possible hom. opts is pessimist anyway and might become 
rather inaccurate if many operations are performed, reducing the prediction by 
one is acceptable.

Modified: gnunet/src/util/crypto_paillier.c
===================================================================
--- gnunet/src/util/crypto_paillier.c   2014-01-29 14:28:07 UTC (rev 32072)
+++ gnunet/src/util/crypto_paillier.c   2014-01-29 14:34:33 UTC (rev 32073)
@@ -16,7 +16,7 @@
      along with GNUnet; see the file COPYING.  If not, write to the
      Free Software Foundation, Inc., 59 Temple Place - Suite 330,
      Boston, MA 02111-1307, USA.
-*/
+ */
 
 /**
  * @file util/crypto_paillier.c
@@ -63,7 +63,8 @@
                                              GCRY_WEAK_RANDOM, 0));
     GNUNET_assert (0 == gcry_prime_generate (&q, GNUNET_CRYPTO_PAILLIER_BITS / 
2, 0, NULL, NULL, NULL,
                                              GCRY_WEAK_RANDOM, 0));
-  } while (0 == gcry_mpi_cmp (p, q));
+  }
+  while (0 == gcry_mpi_cmp (p, q));
   gcry_mpi_mul (n, p, q);
   GNUNET_CRYPTO_mpi_print_unsigned (public_key, sizeof (struct 
GNUNET_CRYPTO_PaillierPublicKey), n);
 
@@ -107,24 +108,24 @@
   gcry_mpi_t n;
   gcry_mpi_t tmp1;
   gcry_mpi_t tmp2;
-  
+
   // determine how many operations we could allow, if the other number
   // has the same length. 
-  GNUNET_assert (NULL != (tmp1 = gcry_mpi_set_ui(NULL, 1))); 
-  GNUNET_assert (NULL != (tmp2 = gcry_mpi_set_ui(NULL, 2))); 
-  gcry_mpi_mul_2exp(tmp1,tmp1,GNUNET_CRYPTO_PAILLIER_BITS);
-  
-  for (possible_opts = -1; gcry_mpi_cmp(tmp1, m) > 0; possible_opts++){
-    gcry_mpi_div(tmp1, NULL, tmp1, tmp2, 0);
+  GNUNET_assert (NULL != (tmp1 = gcry_mpi_set_ui (NULL, 1)));
+  GNUNET_assert (NULL != (tmp2 = gcry_mpi_set_ui (NULL, 2)));
+  gcry_mpi_mul_2exp (tmp1, tmp1, GNUNET_CRYPTO_PAILLIER_BITS);
+
+  for (possible_opts = -2; gcry_mpi_cmp (tmp1, m) > 0; possible_opts++) {
+    gcry_mpi_div (tmp1, NULL, tmp1, tmp2, 0);
   }
-  gcry_mpi_release(tmp1);
-  gcry_mpi_release(tmp2);
+  gcry_mpi_release (tmp1);
+  gcry_mpi_release (tmp2);
   if (possible_opts < 1)
     return -1;
   else
     // reduce by one to guarantee the final homomorphic operation
-    ciphertext->remaining_ops = htonl(possible_opts);
-  
+    ciphertext->remaining_ops = htonl (possible_opts);
+
   GNUNET_assert (0 != (n_square = gcry_mpi_new (0)));
   GNUNET_assert (0 != (r = gcry_mpi_new (0)));
   GNUNET_assert (0 != (g = gcry_mpi_new (0)));
@@ -135,8 +136,7 @@
   gcry_mpi_mul (n_square, n, n);
 
   // generate r < n
-  do
-  {
+  do {
     gcry_mpi_randomize (r, GNUNET_CRYPTO_PAILLIER_BITS, GCRY_WEAK_RANDOM);
   }
   while (gcry_mpi_cmp (r, n) >= 0);
@@ -149,14 +149,14 @@
   // c <- r*c mod n^2
   gcry_mpi_mulm (c, r, c, n_square);
 
-  GNUNET_CRYPTO_mpi_print_unsigned (ciphertext->bits, 
-                                    sizeof ciphertext->bits, 
+  GNUNET_CRYPTO_mpi_print_unsigned (ciphertext->bits,
+                                    sizeof ciphertext->bits,
                                     c);
 
   gcry_mpi_release (n_square);
   gcry_mpi_release (r);
   gcry_mpi_release (c);
-  
+
   return possible_opts;
 }
 
@@ -230,29 +230,29 @@
   gcry_mpi_t n_square;
   int32_t o1;
   int32_t o2;
-  
-  o1 = ntohl(c1->remaining_ops);
-  o2 = ntohl(c2->remaining_ops);
+
+  o1 = ntohl (c1->remaining_ops);
+  o2 = ntohl (c2->remaining_ops);
   if (0 >= o1 || 0 >= o2)
     return GNUNET_SYSERR;
-  
+
   GNUNET_assert (0 != (c = gcry_mpi_new (0)));
-  
+
   GNUNET_CRYPTO_mpi_scan_unsigned (&a, c1->bits, sizeof c1->bits);
   GNUNET_CRYPTO_mpi_scan_unsigned (&b, c1->bits, sizeof c2->bits);
   GNUNET_CRYPTO_mpi_scan_unsigned (&n_square, public_key, sizeof *public_key);
-  gcry_mpi_mul(n_square, n_square,n_square);
-  gcry_mpi_mulm(c,a,b,n_square);
-  
-  result->remaining_ops = htonl(((o2 > o1) ? o1 : o2) - 1);
-  GNUNET_CRYPTO_mpi_print_unsigned (result->bits, 
-                                    sizeof result->bits, 
+  gcry_mpi_mul (n_square, n_square, n_square);
+  gcry_mpi_mulm (c, a, b, n_square);
+
+  result->remaining_ops = htonl (((o2 > o1) ? o1 : o2) - 1);
+  GNUNET_CRYPTO_mpi_print_unsigned (result->bits,
+                                    sizeof result->bits,
                                     c);
   gcry_mpi_release (a);
   gcry_mpi_release (b);
   gcry_mpi_release (c);
   gcry_mpi_release (n_square);
-  return ntohl(result->remaining_ops);
+  return ntohl (result->remaining_ops);
 }
 
 
@@ -265,8 +265,8 @@
 int
 GNUNET_CRYPTO_paillier_hom_get_remaining (const struct 
GNUNET_CRYPTO_PaillierCiphertext *c)
 {
-  GNUNET_assert(NULL != c);
-  return ntohl(c->remaining_ops);
+  GNUNET_assert (NULL != c);
+  return ntohl (c->remaining_ops);
 }
 
 /* end of crypto_paillier.c */

Modified: gnunet/src/util/test_crypto_paillier.c
===================================================================
--- gnunet/src/util/test_crypto_paillier.c      2014-01-29 14:28:07 UTC (rev 
32072)
+++ gnunet/src/util/test_crypto_paillier.c      2014-01-29 14:34:33 UTC (rev 
32073)
@@ -51,10 +51,10 @@
   GNUNET_assert (NULL != (hom_result = gcry_mpi_new (0)));
   //gcry_mpi_randomize (m1, GNUNET_CRYPTO_PAILLIER_BITS-2, GCRY_WEAK_RANDOM);
   m1 = gcry_mpi_set_ui(m1,1);
-  gcry_mpi_mul_2exp(m1,m1,GNUNET_CRYPTO_PAILLIER_BITS-2);
+  gcry_mpi_mul_2exp(m1,m1,GNUNET_CRYPTO_PAILLIER_BITS-3);
   //gcry_mpi_randomize (m2, GNUNET_CRYPTO_PAILLIER_BITS-2, GCRY_WEAK_RANDOM);
   m2 = gcry_mpi_set_ui(m2,1);
-  gcry_mpi_mul_2exp(m2,m2,GNUNET_CRYPTO_PAILLIER_BITS-2);
+  gcry_mpi_mul_2exp(m2,m2,GNUNET_CRYPTO_PAILLIER_BITS-3);
   gcry_mpi_add(result,m1,m2);
 
   if (1 != (ret = GNUNET_CRYPTO_paillier_encrypt (&public_key, m1, &c1))){