[taler-exchange] 08/37: fixed CS signatures and cleanup/refactoring

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gian-demarmels pushed a commit to branch master
in repository exchange.

commit ca247f6f5821415b8c3437916e473785d6fd6403
Author: Gian Demarmels <gian@demarmels.org>
AuthorDate: Mon Dec 27 16:21:26 2021 +0100

    fixed CS signatures and cleanup/refactoring
---
 src/include/taler_crypto_lib.h | 89 +++++++-----------------------------------
 src/util/crypto.c              | 12 +++---
 src/util/denom.c               | 49 ++++++-----------------
 src/util/test_crypto.c         | 24 +++++-------
 4 files changed, 40 insertions(+), 134 deletions(-)

diff --git a/src/include/taler_crypto_lib.h b/src/include/taler_crypto_lib.h
index 87e38896..3de843a2 100644
--- a/src/include/taler_crypto_lib.h
+++ b/src/include/taler_crypto_lib.h
@@ -353,12 +353,12 @@ struct TALER_CoinSpendSignatureP
 
 /**
  * @brief Type of blinding keys for Taler.
- * must be 32 bytes
+ * must be 32 bytes (DB)
  */
 union TALER_DenominationBlindingKeyP
 {
   /**
-   * Clause Schnorr Signatures have 2 blinding secrets, each containing two 
unpredictable values.
+   * Clause Schnorr Signatures have 2 blinding secrets, each containing two 
unpredictable values. (must be 32 bytes)
    */
   struct GNUNET_CRYPTO_CsNonce nonce;
 
@@ -618,10 +618,9 @@ struct TALER_DenominationSignature
 };
 
 /**
- * The Sign Answer for Clause B lind Schnorr signature.
+ * The Sign Answer for Clause Blind Schnorr signature.
  * The sign operation returns a parameter @param b and the signature
  * scalar @param s_scalar.
- * The function does not return the whole signature, due to that is only the 
blinded s_scalar.
  */
 struct TALER_BlindedDenominationCsSignAnswer
 {
@@ -833,57 +832,6 @@ struct TALER_DenominationCsPrivateR
   struct GNUNET_CRYPTO_CsRSecret r[2];
 };
 
-/**
- * @brief RSA Parameters to create blinded messages
- *
- */
-struct TALER_DenominationBlindMessageRsaParams
-{
-  /**
-   * blinded message to be signed
-   * Note: is malloc()'ed!
-   */
-  void **coin_ev;
-
-  /**
-   * size of the blinded message to be signed
-   */
-  size_t *coin_ev_size;
-};
-
-
-/**
- * @brief CS Parameters to create blinded messages
- *
- */
-struct TALER_DenominationBlindMessageCsParams
-{
-
-};
-
-/**
- * @brief Type including Parameters to create blinded message
- *
- */
-struct TALER_DenominationBlindMessageParams
-{
-  /**
-   * Details, depending on @e cipher.
-   */
-  union
-  {
-    /**
-     * If we use #TALER_DENOMINATION_CS in @a cipher.
-     */
-    struct TALER_DenominationBlindMessageCsParams cs_blind_msg_params;
-
-    /**
-     * If we use #TALER_DENOMINATION_RSA in @a cipher.
-     */
-    struct TALER_DenominationBlindMessageRsaParams rsa_blind_msg_params;
-
-  } details;
-};
 
 /**
  * @brief Public information about a coin (including the public key
@@ -968,6 +916,9 @@ TALER_cs_withdraw_nonce_derive (const struct
  * Create a blinding secret @a bs for @a cipher.
  *
  * @param[out] bs blinding secret to initialize
+ * @param cipher algorithm to use (CS or RSA)
+ * @param ... If CS signature, R_0 and R_1 (TALER_DenominationCsPublicR)
+ * and the coins private key is needed
  */
 void
 TALER_blinding_secret_create (union TALER_DenominationBlindingKeyP *bs,
@@ -1013,20 +964,6 @@ void
 TALER_denom_sig_free (struct TALER_DenominationSignature *denom_sig);
 
 
-/**
- * Function for CS signatures to derive the secret r_0 and r_1
- *
- * @param nonce withdraw nonce from a client
- * @param denom_priv denomination privkey as long-term secret
- * @param r the resulting r_0 and r_1
- * @return enum GNUNET_GenericReturnValue, returns SYSERR when denom key has 
wrong type
- */
-enum GNUNET_GenericReturnValue
-TALER_denom_cs_derive_r_secret (const struct TALER_WithdrawNonce *nonce,
-                                const struct
-                                TALER_DenominationPrivateKey *denom_priv,
-                                struct TALER_DenominationCsPrivateR *r);
-
 /**
  * @brief Function for CS signatures to derive public R_0 and R_1
  *
@@ -1053,6 +990,7 @@ TALER_denom_cs_derive_r_public (const struct 
TALER_WithdrawNonce *nonce,
  * @param[out] c_hash resulting hashed coin
  * @param[out] coin_ev blinded coin to submit
  * @param[out] coin_ev_size number of bytes in @a coin_ev
+ * @param ... cipher-specific parameters
  * @return #GNUNET_OK on success
  */
 enum GNUNET_GenericReturnValue
@@ -1070,8 +1008,8 @@ TALER_denom_blind (const struct 
TALER_DenominationPublicKey *dk,
  *
  * @param[out] denom_sig where to write the signature
  * @param denom_priv private key to use for signing
- * @param blinded_msg message to sign
- * @param blinded_msg_size number of bytes in @a blinded_msg
+ * @param blinded_planchet the planchet already blinded
+ * @param ... If CS signature, a TALER_WithdrawNonce is needed
  * @return #GNUNET_OK on success
  */
 enum GNUNET_GenericReturnValue
@@ -1088,6 +1026,7 @@ TALER_denom_sign_blinded (struct 
TALER_BlindedDenominationSignature *denom_sig,
  * @param bdenom_sig the blinded signature
  * @param bks blinding secret to use
  * @param denom_pub public key used for signing
+ * @param ... cipher-specific parameters
  * @return #GNUNET_OK on success
  */
 enum GNUNET_GenericReturnValue
@@ -1125,7 +1064,7 @@ TALER_denom_pub_hash (const struct 
TALER_DenominationPublicKey *denom_pub,
  * @a denom_dst.
  *
  * @param[out] denom_dst target to copy to
- * @param denom_str public key to copy
+ * @param denom_src public key to copy
  */
 void
 TALER_denom_pub_deep_copy (struct TALER_DenominationPublicKey *denom_dst,
@@ -1137,7 +1076,7 @@ TALER_denom_pub_deep_copy (struct 
TALER_DenominationPublicKey *denom_dst,
  * @a denom_dst.
  *
  * @param[out] denom_dst target to copy to
- * @param denom_str public key to copy
+ * @param denom_src public key to copy
  */
 void
 TALER_denom_sig_deep_copy (struct TALER_DenominationSignature *denom_dst,
@@ -1149,7 +1088,7 @@ TALER_denom_sig_deep_copy (struct 
TALER_DenominationSignature *denom_dst,
  * @a denom_dst.
  *
  * @param[out] denom_dst target to copy to
- * @param denom_str public key to copy
+ * @param denom_src public key to copy
  */
 void
 TALER_blinded_denom_sig_deep_copy (
@@ -1466,6 +1405,7 @@ TALER_planchet_setup_random (struct 
TALER_PlanchetSecretsP *ps,
  * @param[out] c_hash set to the hash of the public key of the coin (needed 
later)
  * @param[out] pd set to the planchet detail for TALER_MERCHANT_tip_pickup() 
and
  *               other withdraw operations
+ * @param ... cipher-specific parameters
  * @return #GNUNET_OK on success
  */
 enum GNUNET_GenericReturnValue
@@ -1485,6 +1425,7 @@ TALER_planchet_prepare (const struct 
TALER_DenominationPublicKey *dk,
  * @param ps secrets from #TALER_planchet_prepare()
  * @param c_hash hash of the coin's public key for verification of the 
signature
  * @param[out] coin set to the details of the fresh coin
+ * @param ... cipher-specific parameters
  * @return #GNUNET_OK on success
  */
 enum GNUNET_GenericReturnValue
diff --git a/src/util/crypto.c b/src/util/crypto.c
index 03a438d2..1e5033a0 100644
--- a/src/util/crypto.c
+++ b/src/util/crypto.c
@@ -247,7 +247,7 @@ TALER_blinding_secret_create (union 
TALER_DenominationBlindingKeyP *bs,
 /**
  * @brief setup a random planchet
  * In Case of RSA planchet, the bks gets set
- * In Case of Schnorr this will be set in future
+ * In Case of Clause Schnorr this will be set in future
  */
 void
 TALER_planchet_setup_random (struct TALER_PlanchetSecretsP *ps,
@@ -307,11 +307,9 @@ TALER_planchet_prepare (const struct 
TALER_DenominationPublicKey *dk,
     {
       va_list ap;
       va_start (ap, pd);
-      struct TALER_WithdrawNonce *nonce;
       struct TALER_DenominationCsPublicR *r_pub;
       struct TALER_DenominationCsPublicR *blinded_r_pub;
 
-      nonce = va_arg (ap, struct TALER_WithdrawNonce *);
       r_pub = va_arg (ap, struct TALER_DenominationCsPublicR *);
       blinded_r_pub = va_arg (ap, struct TALER_DenominationCsPublicR *);
 
@@ -322,7 +320,6 @@ TALER_planchet_prepare (const struct 
TALER_DenominationPublicKey *dk,
                              &coin_pub,
                              c_hash,
                              &pd->blinded_planchet,
-                             nonce,
                              r_pub,
                              blinded_r_pub))
       {
@@ -373,14 +370,14 @@ TALER_planchet_to_coin (
       va_list ap;
       va_start (ap, coin);
 
-      struct TALER_DenominationCsPublicR *r_pub_dash;
-      r_pub_dash = va_arg (ap, struct TALER_DenominationCsPublicR *);
+      struct TALER_DenominationCsPublicR *r_pub_blind;
+      r_pub_blind = va_arg (ap, struct TALER_DenominationCsPublicR *);
       if (GNUNET_OK !=
           TALER_denom_sig_unblind (&sig,
                                    blind_sig,
                                    &ps->blinding_key,
                                    dk,
-                                   r_pub_dash))
+                                   r_pub_blind))
       {
         GNUNET_break_op (0);
         va_end (ap);
@@ -403,6 +400,7 @@ TALER_planchet_to_coin (
     TALER_denom_sig_free (&sig);
     return GNUNET_SYSERR;
   }
+
   coin->sig = sig;
   coin->coin_priv = ps->coin_priv;
   return GNUNET_OK;
diff --git a/src/util/denom.c b/src/util/denom.c
index ada2289c..12b499aa 100644
--- a/src/util/denom.c
+++ b/src/util/denom.c
@@ -81,25 +81,6 @@ TALER_denom_priv_create (struct TALER_DenominationPrivateKey 
*denom_priv,
 }
 
 
-enum GNUNET_GenericReturnValue
-TALER_denom_cs_derive_r_secret (const struct TALER_WithdrawNonce *nonce,
-                                const struct
-                                TALER_DenominationPrivateKey *denom_priv,
-                                struct TALER_DenominationCsPrivateR *r)
-{
-  if (denom_priv->cipher != TALER_DENOMINATION_CS)
-  {
-    GNUNET_break (0);
-    return GNUNET_SYSERR;
-  }
-
-  GNUNET_CRYPTO_cs_r_derive (&nonce->nonce,
-                             &denom_priv->details.cs_private_key,
-                             r->r);
-  return GNUNET_OK;
-}
-
-
 enum GNUNET_GenericReturnValue
 TALER_denom_cs_derive_r_public (const struct TALER_WithdrawNonce *nonce,
                                 const struct
@@ -216,26 +197,19 @@ TALER_denom_sig_unblind (
     {
       va_list ap;
       va_start (ap, denom_pub);
-      struct TALER_DenominationCsPublicR *r_pub_dash;
-      r_pub_dash = va_arg (ap, struct TALER_DenominationCsPublicR *);
+      struct TALER_DenominationCsPublicR *r_pub_blind;
+      r_pub_blind = va_arg (ap, struct TALER_DenominationCsPublicR *);
 
       struct GNUNET_CRYPTO_CsBlindingSecret bs[2];
       GNUNET_CRYPTO_cs_blinding_secrets_derive (&bks->nonce, bs);
 
-      struct GNUNET_CRYPTO_CsS s_scalar;
-
       GNUNET_CRYPTO_cs_unblind 
(&bdenom_sig->details.blinded_cs_answer.s_scalar,
                                 &bs[bdenom_sig->details.blinded_cs_answer.b],
-                                &s_scalar);
-
-      // TODO: This seems to work, but is this a good idea?
-      // Not working:
-      // denom_sig->details.cs_signature.r_point = 
r_pub_dash->r_pub[bdenom_sig->details.blinded_cs_answer.b];
-      GNUNET_memcpy (&denom_sig->details.cs_signature, &s_scalar, sizeof(struct
-                                                                         
GNUNET_CRYPTO_CsS));
-      GNUNET_memcpy (&denom_sig->details.cs_signature + sizeof(struct
-                                                               
GNUNET_CRYPTO_CsS),
-                     
&r_pub_dash->r_pub[bdenom_sig->details.blinded_cs_answer.b],
+                                &denom_sig->details.cs_signature.s_scalar);
+
+      GNUNET_memcpy (&denom_sig->details.cs_signature.r_point,
+                     
&r_pub_blind->r_pub[bdenom_sig->details.blinded_cs_answer.b
+                     ],
                      sizeof(struct GNUNET_CRYPTO_CsRPublic));
 
       denom_sig->cipher = TALER_DENOMINATION_CS;
@@ -362,16 +336,14 @@ TALER_denom_blind (const struct 
TALER_DenominationPublicKey *dk,
     {
       va_list ap;
       va_start (ap, blinded_planchet);
-      struct TALER_WithdrawNonce *nonce;
       struct TALER_DenominationCsPublicR *r_pub;
       struct TALER_DenominationCsPublicR *blinded_r_pub;
 
-      nonce = va_arg (ap, struct TALER_WithdrawNonce *);
       r_pub = va_arg (ap, struct TALER_DenominationCsPublicR *);
       blinded_r_pub = va_arg (ap, struct TALER_DenominationCsPublicR *);
 
       struct GNUNET_CRYPTO_CsBlindingSecret bs[2];
-      GNUNET_CRYPTO_cs_blinding_secrets_derive (&nonce->nonce, bs);
+      GNUNET_CRYPTO_cs_blinding_secrets_derive (&coin_bks->nonce, bs);
 
       GNUNET_CRYPTO_cs_calc_blinded_c (bs,
                                        r_pub->r_pub,
@@ -422,11 +394,12 @@ TALER_denom_pub_verify (const struct 
TALER_DenominationPublicKey *denom_pub,
     if (GNUNET_OK !=
         GNUNET_CRYPTO_cs_verify (&denom_sig->details.cs_signature,
                                  &denom_pub->details.cs_public_key,
-                                 c_hash,
-                                 sizeof(*c_hash)))
+                                 &c_hash->hash,
+                                 sizeof(struct GNUNET_HashCode)))
     {
       GNUNET_log (GNUNET_ERROR_TYPE_WARNING,
                   "Coin signature is invalid\n");
+      // return GNUNET_YES;
       return GNUNET_NO;
     }
     return GNUNET_YES;
diff --git a/src/util/test_crypto.c b/src/util/test_crypto.c
index 64958cfc..760ec0fa 100644
--- a/src/util/test_crypto.c
+++ b/src/util/test_crypto.c
@@ -149,7 +149,6 @@ test_planchets_cs (void)
   struct TALER_WithdrawNonce nonce;
   struct TALER_DenominationCsPublicR r_pub;
   struct TALER_DenominationCsPublicR r_pub_blind;
-  struct TALER_DenominationCsPrivateR priv_r;
   struct TALER_BlindedDenominationSignature blind_sig;
   struct TALER_FreshCoin coin;
 
@@ -174,30 +173,25 @@ test_planchets_cs (void)
                                          &ps,
                                          &c_hash,
                                          &pd,
-                                         &nonce,
                                          &r_pub,
                                          &r_pub_blind));
-  // TODO: Remove r_secret if not needed
-  GNUNET_assert (GNUNET_OK ==
-                 TALER_denom_cs_derive_r_secret (&nonce,
-                                                 &dk_priv,
-                                                 &priv_r));
+
   GNUNET_assert (GNUNET_OK ==
                  TALER_denom_sign_blinded (&blind_sig,
                                            &dk_priv,
                                            &pd.blinded_planchet,
                                            &nonce));
 
-  // GNUNET_assert (GNUNET_OK ==
-  //                TALER_planchet_to_coin (&dk_pub,
-  //                                        &blind_sig,
-  //                                        &ps,
-  //                                        &c_hash,
-  //                                        &coin,
-  //                                        &r_pub_blind));
+  GNUNET_assert (GNUNET_OK ==
+                 TALER_planchet_to_coin (&dk_pub,
+                                         &blind_sig,
+                                         &ps,
+                                         &c_hash,
+                                         &coin,
+                                         &r_pub_blind));
 
   TALER_blinded_denom_sig_free (&blind_sig);
-  // TALER_denom_sig_free (&coin.sig);
+  TALER_denom_sig_free (&coin.sig);
   TALER_denom_priv_free (&dk_priv);
   TALER_denom_pub_free (&dk_pub);
   return 0;

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