[taler-exchange] 79/130: more crypto refactoring

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grothoff pushed a commit to branch master
in repository exchange.

commit c3e244322b6b7234c0234471b07d67bf6a210b91
Author: Christian Grothoff <christian@grothoff.org>
AuthorDate: Fri Nov 5 23:01:21 2021 +0100

    more crypto refactoring
---
 src/exchange/taler-exchange-httpd_recoup.c | 44 +++++++++++++++---------------
 src/include/taler_crypto_lib.h             | 20 ++++++++++++++
 src/util/crypto.c                          | 22 +++++----------
 src/util/denom.c                           | 32 ++++++++++++++++++++++
 4 files changed, 81 insertions(+), 37 deletions(-)

diff --git a/src/exchange/taler-exchange-httpd_recoup.c 
b/src/exchange/taler-exchange-httpd_recoup.c
index f10bd34b..be4471c0 100644
--- a/src/exchange/taler-exchange-httpd_recoup.c
+++ b/src/exchange/taler-exchange-httpd_recoup.c
@@ -352,8 +352,6 @@ verify_and_execute_recoup (
   struct RecoupContext pc;
   const struct TEH_DenominationKey *dk;
   struct TALER_CoinPubHash c_hash;
-  void *coin_ev;
-  size_t coin_ev_size;
   MHD_RESULT mret;
 
   /* check denomination exists and is in recoup mode */
@@ -442,28 +440,30 @@ verify_and_execute_recoup (
                                          NULL);
     }
   }
-  TALER_coin_pub_hash (&coin->coin_pub,
-                       &c_hash);
-  GNUNET_assert (dk->denom_pub.cipher ==
-                 TALER_DENOMINATION_RSA);
-  // FIXME-RSA migration...
-  if (GNUNET_YES !=
-      TALER_rsa_blind (&c_hash,
-                       &coin_bks->rsa_bks,
-                       dk->denom_pub.details.rsa_public_key,
-                       &coin_ev,
-                       &coin_ev_size))
+
   {
-    GNUNET_break (0);
-    return TALER_MHD_reply_with_error (connection,
-                                       MHD_HTTP_INTERNAL_SERVER_ERROR,
-                                       
TALER_EC_EXCHANGE_RECOUP_BLINDING_FAILED,
-                                       NULL);
+    void *coin_ev;
+    size_t coin_ev_size;
+
+    if (GNUNET_OK !=
+        TALER_denom_blind (&dk->denom_pub,
+                           coin_bks,
+                           &coin->coin_pub,
+                           &c_hash,
+                           &coin_ev,
+                           &coin_ev_size))
+    {
+      GNUNET_break (0);
+      return TALER_MHD_reply_with_error (connection,
+                                         MHD_HTTP_INTERNAL_SERVER_ERROR,
+                                         
TALER_EC_EXCHANGE_RECOUP_BLINDING_FAILED,
+                                         NULL);
+    }
+    TALER_coin_ev_hash (coin_ev,
+                        coin_ev_size,
+                        &pc.h_blind);
+    GNUNET_free (coin_ev);
   }
-  TALER_coin_ev_hash (coin_ev,
-                      coin_ev_size,
-                      &pc.h_blind);
-  GNUNET_free (coin_ev);
 
   /* Perform actual recoup transaction */
   pc.coin_sig = coin_sig;
diff --git a/src/include/taler_crypto_lib.h b/src/include/taler_crypto_lib.h
index 0a0be0cb..8907ca43 100644
--- a/src/include/taler_crypto_lib.h
+++ b/src/include/taler_crypto_lib.h
@@ -724,6 +724,26 @@ void
 TALER_denom_sig_free (struct TALER_DenominationSignature *denom_sig);
 
 
+/**
+ * Blind coin for blind signing with @a dk using blinding secret @a coin_bks.
+ *
+ * @param dk denomination public key to blind for
+ * @param coin_bks blinding secret to use
+ * @param coin_pub public key of the coin to blind
+ * @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
+ * @return #GNUNET_OK on success
+ */
+enum GNUNET_GenericReturnValue
+TALER_denom_blind (const struct TALER_DenominationPublicKey *dk,
+                   const union TALER_DenominationBlindingKeyP *coin_bks,
+                   const struct TALER_CoinSpendPublicKeyP *coin_pub,
+                   struct TALER_CoinPubHash *c_hash,
+                   void **coin_ev,
+                   size_t *coin_ev_size);
+
+
 /**
  * Create blinded signature.
  *
diff --git a/src/util/crypto.c b/src/util/crypto.c
index 7d4a431c..ed32f31d 100644
--- a/src/util/crypto.c
+++ b/src/util/crypto.c
@@ -185,21 +185,13 @@ TALER_planchet_prepare (const struct 
TALER_DenominationPublicKey *dk,
 
   GNUNET_CRYPTO_eddsa_key_get_public (&ps->coin_priv.eddsa_priv,
                                       &coin_pub.eddsa_pub);
-  // FIXME-Oec: replace with function that
-  // also hashes the age vector if we have
-  // one!
-  TALER_coin_pub_hash (&coin_pub,
-                       c_hash);
-  // FIXME-Gian/Lucien: this will be the bigger
-  // change, as you have the extra round trip
-  // => to be discussed!
-  GNUNET_assert (TALER_DENOMINATION_RSA == dk->cipher);
-  if (GNUNET_YES !=
-      TALER_rsa_blind (c_hash,
-                       &ps->blinding_key.rsa_bks,
-                       dk->details.rsa_public_key,
-                       &pd->coin_ev,
-                       &pd->coin_ev_size))
+  if (GNUNET_OK !=
+      TALER_denom_blind (dk,
+                         &ps->blinding_key,
+                         &coin_pub,
+                         c_hash,
+                         &pd->coin_ev,
+                         &pd->coin_ev_size))
   {
     GNUNET_break_op (0);
     return GNUNET_SYSERR;
diff --git a/src/util/denom.c b/src/util/denom.c
index 4a47c66d..4f1fc8e5 100644
--- a/src/util/denom.c
+++ b/src/util/denom.c
@@ -216,6 +216,38 @@ TALER_denom_priv_to_pub (const struct 
TALER_DenominationPrivateKey *denom_priv,
 }
 
 
+enum GNUNET_GenericReturnValue
+TALER_denom_blind (const struct TALER_DenominationPublicKey *dk,
+                   const union TALER_DenominationBlindingKeyP *coin_bks,
+                   const struct TALER_CoinSpendPublicKeyP *coin_pub,
+                   struct TALER_CoinPubHash *c_hash,
+                   void **coin_ev,
+                   size_t *coin_ev_size)
+{
+  switch (dk->cipher)
+  {
+  case TALER_DENOMINATION_RSA:
+    TALER_coin_pub_hash (coin_pub,
+                         c_hash);
+    if (GNUNET_YES !=
+        TALER_rsa_blind (c_hash,
+                         &coin_bks->rsa_bks,
+                         dk->details.rsa_public_key,
+                         coin_ev,
+                         coin_ev_size))
+    {
+      GNUNET_break (0);
+      return GNUNET_SYSERR;
+    }
+    return GNUNET_OK;
+  // TODO: add case for Clause-Schnorr
+  default:
+    GNUNET_break (0);
+    return GNUNET_SYSERR;
+  }
+}
+
+
 enum GNUNET_GenericReturnValue
 TALER_denom_pub_verify (const struct TALER_DenominationPublicKey *denom_pub,
                         const struct TALER_DenominationSignature *denom_sig,

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