From eaf9d728f54681be4e9ed3467ff9d10e71ad2b04 Mon Sep 17 00:00:00 2001
From: Christian Grothoff <christian@grothoff.org>
Date: Fri, 5 Nov 2021 22:48:11 +0100
Subject: more crypto refactoring

---
 src/include/taler_crypto_lib.h | 15 ---------------
 src/lib/exchange_api_link.c    | 16 +++++++++-------
 src/util/crypto.c              | 37 ++++++++++++-------------------------
 src/util/denom.c               |  2 +-
 4 files changed, 22 insertions(+), 48 deletions(-)

(limited to 'src')

diff --git a/src/include/taler_crypto_lib.h b/src/include/taler_crypto_lib.h
index 961c36695..0a0be0cb7 100644
--- a/src/include/taler_crypto_lib.h
+++ b/src/include/taler_crypto_lib.h
@@ -2165,19 +2165,4 @@ TALER_rsa_blind (const struct TALER_CoinPubHash *hash,
                  size_t *buf_size);
 
 
-/**
- * Unblind a blind-signed signature.  The signature should have been generated
- * with GNUNET_CRYPTO_rsa_sign() using a hash that was blinded with
- * GNUNET_CRYPTO_rsa_blind().
- *
- * @param sig the signature made on the blinded signature purpose
- * @param bks the blinding key secret used to blind the signature purpose
- * @param pkey the public key of the signer
- * @return unblinded signature on success, NULL if RSA key is bad or malicious.
- */
-struct GNUNET_CRYPTO_RsaSignature *
-TALER_rsa_unblind (const struct GNUNET_CRYPTO_RsaSignature *sig,
-                   const struct GNUNET_CRYPTO_RsaBlindingKeySecret *bks,
-                   struct GNUNET_CRYPTO_RsaPublicKey *pkey);
-
 #endif
diff --git a/src/lib/exchange_api_link.c b/src/lib/exchange_api_link.c
index f544e71e3..a9dc8852f 100644
--- a/src/lib/exchange_api_link.c
+++ b/src/lib/exchange_api_link.c
@@ -123,14 +123,16 @@ parse_link_coin (const struct TALER_EXCHANGE_LinkHandle *lh,
                                 &fc);
 
   /* extract coin and signature */
+  if (GNUNET_OK !=
+      TALER_denom_sig_unblind (sig,
+                               &bsig,
+                               &fc.blinding_key,
+                               &rpub))
+  {
+    GNUNET_break_op (0);
+    return GNUNET_SYSERR;
+  }
   *coin_priv = fc.coin_priv;
-  // FIXME: use more generlized unblinding API!
-  GNUNET_assert (TALER_DENOMINATION_RSA == bsig.cipher);
-  sig->cipher = TALER_DENOMINATION_RSA;
-  sig->details.rsa_signature
-    = TALER_rsa_unblind (bsig.details.blinded_rsa_signature,
-                         &fc.blinding_key.rsa_bks,
-                         rpub.details.rsa_public_key);
   /* verify link_sig */
   {
     struct TALER_PlanchetDetail pd;
diff --git a/src/util/crypto.c b/src/util/crypto.c
index 668a91adf..7d4a431c6 100644
--- a/src/util/crypto.c
+++ b/src/util/crypto.c
@@ -188,9 +188,8 @@ TALER_planchet_prepare (const struct TALER_DenominationPublicKey *dk,
   // FIXME-Oec: replace with function that
   // also hashes the age vector if we have
   // one!
-  GNUNET_CRYPTO_hash (&coin_pub.eddsa_pub,
-                      sizeof (struct GNUNET_CRYPTO_EcdsaPublicKey),
-                      &c_hash->hash);
+  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!
@@ -221,23 +220,22 @@ TALER_planchet_to_coin (
 {
   struct TALER_DenominationSignature sig;
 
-  // FIXME-Gian/Lucien: this may need a bigger
-  // change, as you have the extra round trip
-  // => to be discussed!
-  GNUNET_assert (TALER_DENOMINATION_RSA == dk->cipher);
-  GNUNET_assert (TALER_DENOMINATION_RSA == blind_sig->cipher);
-  sig.cipher = TALER_DENOMINATION_RSA;
-  sig.details.rsa_signature
-    = TALER_rsa_unblind (blind_sig->details.blinded_rsa_signature,
-                         &ps->blinding_key.rsa_bks,
-                         dk->details.rsa_public_key);
+  if (GNUNET_OK !=
+      TALER_denom_sig_unblind (&sig,
+                               blind_sig,
+                               &ps->blinding_key,
+                               dk))
+  {
+    GNUNET_break_op (0);
+    return GNUNET_SYSERR;
+  }
   if (GNUNET_OK !=
       TALER_denom_pub_verify (dk,
                               &sig,
                               c_hash))
   {
     GNUNET_break_op (0);
-    GNUNET_CRYPTO_rsa_signature_free (sig.details.rsa_signature);
+    TALER_denom_sig_free (&sig);
     return GNUNET_SYSERR;
   }
   coin->sig = sig;
@@ -330,17 +328,6 @@ TALER_rsa_blind (const struct TALER_CoinPubHash *hash,
 }
 
 
-struct GNUNET_CRYPTO_RsaSignature *
-TALER_rsa_unblind (const struct GNUNET_CRYPTO_RsaSignature *sig,
-                   const struct GNUNET_CRYPTO_RsaBlindingKeySecret *bks,
-                   struct GNUNET_CRYPTO_RsaPublicKey *pkey)
-{
-  return GNUNET_CRYPTO_rsa_unblind (sig,
-                                    bks,
-                                    pkey);
-}
-
-
 void
 TALER_coin_ev_hash (const void *coin_ev,
                     size_t coin_ev_size,
diff --git a/src/util/denom.c b/src/util/denom.c
index a1f511fe6..4a47c66d4 100644
--- a/src/util/denom.c
+++ b/src/util/denom.c
@@ -128,7 +128,7 @@ TALER_denom_sig_unblind (
     return GNUNET_SYSERR;
   case TALER_DENOMINATION_RSA:
     denom_sig->details.rsa_signature
-      = TALER_rsa_unblind (
+      = GNUNET_CRYPTO_rsa_unblind (
           bdenom_sig->details.blinded_rsa_signature,
           &bks->rsa_bks,
           denom_pub->details.rsa_public_key);
-- 
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