moving core refresh crypto logic to util -- towards fixing #3777

src/include/taler_crypto_lib.h

@@ -423,6 +423,43 @@ struct TALER_RefreshLinkEncrypted
 };
 
 
+/**
+ * Decrypt the shared @a secret from the information in the
+ * encrypted link secret @e secret_enc using the transfer
+ * private key and the coin's public key.
+ * 
+ * @param secret_enc encrypted link secret
+ * @param transfer_priv transfer private key
+ * @param coin_pub coin public key
+ * @param[out] secret set to the shared secret
+ * @return #GNUNET_OK on success, #GNUNET_SYSERR on error
+ */
+int
+TALER_link_decrypt_secret (const struct TALER_EncryptedLinkSecretP *secret_enc,
+			   const struct TALER_TransferPrivateKeyP *trans_priv,
+			   const union TALER_CoinSpendPublicKeyP *coin_pub,
+			   struct TALER_LinkSecretP *secret);
+
+
+/**
+ * Encrypt the shared @a secret to generate the encrypted link secret.
+ * Also creates the transfer key.
+ * 
+ * @param secret link secret to encrypt 
+ * @param coin_pub coin public key
+ * @param transfer_priv[out] set to transfer private key
+ * @param transfer_pub[out] set to transfer public key
+ * @param[out] secret_enc set to the encryptd @a secret
+ * @return #GNUNET_OK on success, #GNUNET_SYSERR on error
+ */
+int
+TALER_link_encrypt_secret (const struct TALER_LinkSecretP *secret,
+			   const union TALER_CoinSpendPublicKeyP *coin_pub,
+			   struct TALER_TransferPrivateKeyP *trans_priv,
+			   struct TALER_TransferPublicKeyP *trans_pub,
+			   struct TALER_EncryptedLinkSecretP *secret_enc);
+
+
 /**
  * Use the @a trans_sec (from ECDHE) to decrypt the @a secret_enc
  * to obtain the @a secret to decrypt the linkage data.

src/mint/taler-mint-httpd_db.c

@@ -849,7 +849,6 @@ check_commitment (struct MHD_Connection *connection,
 
   for (j = 0; j < num_oldcoins; j++)
   {
-    struct TALER_TransferSecretP transfer_secret;
     struct TALER_LinkSecretP shared_secret;
     struct TALER_TransferPublicKeyP transfer_pub_check;
 
@@ -871,32 +870,18 @@ check_commitment (struct MHD_Connection *connection,
                                          "transfer key");
     }
 
-    /* We're converting key types here, which is not very nice
-     * but necessary and harmless (keys will be thrown away later). */
     if (GNUNET_OK !=
-        GNUNET_CRYPTO_ecc_ecdh (&transfer_privs[j].ecdhe_priv,
+	TALER_link_decrypt_secret (&commit_links[j].shared_secret_enc,
-                                &melts[j].coin.coin_pub.ecdhe_pub,
+				   &transfer_privs[j],
-                                &transfer_secret.key))
+				   &melts[j].coin.coin_pub,
-    {
-      GNUNET_break (0);
-      GNUNET_free (commit_links);
-      return (MHD_YES == TMH_RESPONSE_reply_internal_error (connection,
-                                                            "ECDH error"))
-          ? GNUNET_NO : GNUNET_SYSERR;
-    }
-    if (GNUNET_OK !=
-        TALER_transfer_decrypt (&commit_links[j].shared_secret_enc,
-                                &transfer_secret,
 				   &shared_secret))
     { 
-      GNUNET_break (0);
       GNUNET_free (commit_links);
       return (MHD_YES ==
 	      TMH_RESPONSE_reply_internal_error (connection,
-                                                 "Decryption error"))
+						 "Transfer secret decryption error"))
 	? GNUNET_NO : GNUNET_SYSERR;
     }
-
     if (GNUNET_NO == secret_initialized)
     {
       secret_initialized = GNUNET_YES;

src/util/crypto.c

@@ -1,6 +1,6 @@
 /*
   This file is part of TALER
-  Copyright (C) 2014 Christian Grothoff (and other contributing authors)
+  Copyright (C) 2014, 2015 Christian Grothoff (and other contributing authors)
 
   TALER is free software; you can redistribute it and/or modify it under the
   terms of the GNU General Public License as published by the Free Software
@@ -333,4 +333,91 @@ TALER_test_coin_valid (const struct TALER_CoinPublicInfo *coin_public_info)
 }
 
 
+
+/**
+ * Decrypt the shared @a secret from the information in the
+ * encrypted link secret @e secret_enc using the transfer
+ * private key and the coin's public key.
+ * 
+ * @param secret_enc encrypted link secret
+ * @param transfer_priv transfer private key
+ * @param coin_pub coin public key
+ * @param[out] secret set to the shared secret
+ * @return #GNUNET_OK on success, #GNUNET_SYSERR on error
+ */
+int
+TALER_link_decrypt_secret (const struct TALER_EncryptedLinkSecretP *secret_enc,
+			   const struct TALER_TransferPrivateKeyP *trans_priv,
+			   const union TALER_CoinSpendPublicKeyP *coin_pub,
+			   struct TALER_LinkSecretP *secret)
+{
+  struct TALER_TransferSecretP transfer_secret;
+
+  if (GNUNET_OK !=
+      GNUNET_CRYPTO_ecc_ecdh (&trans_priv->ecdhe_priv,
+			      &coin_pub->ecdhe_pub,
+			      &transfer_secret.key))
+  {
+    GNUNET_break (0);
+    return GNUNET_SYSERR;
+  }
+  if (GNUNET_OK !=
+      TALER_transfer_decrypt (secret_enc,
+			      &transfer_secret,
+			      secret))
+  {
+    GNUNET_break (0);
+    return GNUNET_SYSERR;
+  }
+  return GNUNET_OK;
+}
+
+
+/**
+ * Encrypt the shared @a secret to generate the encrypted link secret.
+ * Also creates the transfer key.
+ * 
+ * @param secret link secret to encrypt 
+ * @param coin_pub coin public key
+ * @param transfer_priv[out] set to transfer private key
+ * @param transfer_pub[out] set to transfer public key
+ * @param[out] secret_enc set to the encryptd @a secret
+ * @return #GNUNET_OK on success, #GNUNET_SYSERR on error
+ */
+int
+TALER_link_encrypt_secret (const struct TALER_LinkSecretP *secret,
+			   const union TALER_CoinSpendPublicKeyP *coin_pub,
+			   struct TALER_TransferPrivateKeyP *trans_priv,
+			   struct TALER_TransferPublicKeyP *trans_pub,
+			   struct TALER_EncryptedLinkSecretP *secret_enc)
+{
+  struct TALER_TransferSecretP transfer_secret;
+  struct GNUNET_CRYPTO_EcdhePrivateKey *pk;
+
+  pk = GNUNET_CRYPTO_ecdhe_key_create ();
+  if (GNUNET_OK !=
+      GNUNET_CRYPTO_ecc_ecdh (pk,
+			      &coin_pub->ecdhe_pub,
+			      &transfer_secret.key))
+  {
+    GNUNET_break (0);
+    GNUNET_free (pk);
+    return GNUNET_SYSERR;
+  }
+  if (GNUNET_OK !=
+      TALER_transfer_encrypt (secret,
+			      &transfer_secret,
+			      secret_enc))
+  {
+    GNUNET_break (0);
+    return GNUNET_SYSERR;
+  }
+  trans_priv->ecdhe_priv = *pk;
+  GNUNET_CRYPTO_ecdhe_key_get_public (pk,
+				      &trans_pub->ecdhe_pub);
+  GNUNET_free (pk);
+  return GNUNET_OK;
+}
+
+
 /* end of crypto.c */