[GNUnet-SVN] r31973 - in gnunet/src: include util

[gnunet]

Author: cfuchs
Date: 2014-01-21 10:31:38 +0100 (Tue, 21 Jan 2014)
New Revision: 31973

Modified:
   gnunet/src/include/gnunet_crypto_lib.h
   gnunet/src/util/crypto_paillier.c
Log:
- first extension of paillier with foolproof homomorphism support (ciphertext 
container carries information on support ops)
- adjusted encryt/decrypt functionality to handle gcry_mpi_t, not a plaintext 
container

Modified: gnunet/src/include/gnunet_crypto_lib.h
===================================================================
--- gnunet/src/include/gnunet_crypto_lib.h      2014-01-21 09:20:23 UTC (rev 
31972)
+++ gnunet/src/include/gnunet_crypto_lib.h      2014-01-21 09:31:38 UTC (rev 
31973)
@@ -383,6 +383,11 @@
 struct GNUNET_CRYPTO_PaillierCiphertext
 {
   /**
+   * guaranteed minimum number of homomorphic operations with this ciphertext
+   */
+  uint32_t remaining_ops GNUNET_PACKED;
+  
+  /**
    * The bits of the ciphertext.
    */
   unsigned char bits[GNUNET_CRYPTO_PAILLIER_BITS * 2 / 8];

Modified: gnunet/src/util/crypto_paillier.c
===================================================================
--- gnunet/src/util/crypto_paillier.c   2014-01-21 09:20:23 UTC (rev 31972)
+++ gnunet/src/util/crypto_paillier.c   2014-01-21 09:31:38 UTC (rev 31973)
@@ -90,29 +90,25 @@
  * Encrypt a plaintext with a paillier public key.
  *
  * @param public_key Public key to use.
- * @param plaintext Plaintext to encrypt.
+ * @param m Plaintext to encrypt.
  * @param[out] ciphertext Encrytion of @a plaintext with @a public_key.
  */
 void
 GNUNET_CRYPTO_paillier_encrypt (const struct GNUNET_CRYPTO_PaillierPublicKey 
*public_key,
-                                const struct GNUNET_CRYPTO_PaillierPlaintext 
*plaintext,
+                                const gcry_mpi_t m,
                                 struct GNUNET_CRYPTO_PaillierCiphertext 
*ciphertext)
 {
   gcry_mpi_t n_square;
   gcry_mpi_t r;
   gcry_mpi_t g;
   gcry_mpi_t c;
-
   gcry_mpi_t n;
-  gcry_mpi_t m;
 
-
   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)));
   GNUNET_assert (0 != (c = gcry_mpi_new (0)));
 
-  GNUNET_CRYPTO_mpi_scan_unsigned (&m, plaintext, sizeof (struct 
GNUNET_CRYPTO_PaillierPlaintext));
   GNUNET_CRYPTO_mpi_scan_unsigned (&n, public_key, sizeof (struct 
GNUNET_CRYPTO_PaillierPublicKey));
 
   gcry_mpi_mul (n_square, n, n);
@@ -132,11 +128,12 @@
   // c <- r*c mod n^2
   gcry_mpi_mulm (c, r, c, n_square);
 
-  GNUNET_CRYPTO_mpi_print_unsigned (ciphertext, sizeof *ciphertext, c);
+  GNUNET_CRYPTO_mpi_print_unsigned (ciphertext->bits, 
+                                    sizeof(*ciphertext) - 
sizeof(ciphertext->remaining_ops), 
+                                    c);
 
   gcry_mpi_release (n_square);
   gcry_mpi_release (r);
-  gcry_mpi_release (m);
   gcry_mpi_release (c);
 }
 
@@ -147,15 +144,14 @@
  * @param private_key Private key to use for decryption.
  * @param public_key Public key to use for decryption.
  * @param ciphertext Ciphertext to decrypt.
- * @param[out] plaintext Decryption of @a ciphertext with @private_key.
+ * @param[out] m Decryption of @a ciphertext with @private_key.
  */
 void
 GNUNET_CRYPTO_paillier_decrypt (const struct GNUNET_CRYPTO_PaillierPrivateKey 
*private_key,
                                 const struct GNUNET_CRYPTO_PaillierPublicKey 
*public_key,
                                 const struct GNUNET_CRYPTO_PaillierCiphertext 
*ciphertext,
-                                struct GNUNET_CRYPTO_PaillierPlaintext 
*plaintext)
+                                gcry_mpi_t *m)
 {
-  gcry_mpi_t m;
   gcry_mpi_t mu;
   gcry_mpi_t lambda;
   gcry_mpi_t n;
@@ -163,7 +159,8 @@
   gcry_mpi_t c;
 
   GNUNET_assert (0 != (n_square = gcry_mpi_new (0)));
-  GNUNET_assert (0 != (m = gcry_mpi_new (0)));
+  if (NULL == *m)
+    GNUNET_assert (0 != (m = gcry_mpi_new (0)));
 
   GNUNET_CRYPTO_mpi_scan_unsigned (&lambda, private_key->lambda, sizeof 
private_key->lambda);
   GNUNET_CRYPTO_mpi_scan_unsigned (&mu, private_key->mu, sizeof 
private_key->mu);
@@ -179,9 +176,6 @@
   gcry_mpi_div (m, NULL, m, n, 0);
   gcry_mpi_mulm (m, m, mu, n);
 
-  GNUNET_CRYPTO_mpi_print_unsigned (plaintext, sizeof *plaintext, m);
-
-  gcry_mpi_release (m);
   gcry_mpi_release (mu);
   gcry_mpi_release (lambda);
   gcry_mpi_release (n);