centralize (most) offline signing/verifying operations into offline_signatures.c

24 files changed, 692 insertions, 324 deletions

diff --git a/src/auditor/taler-auditor-httpd_deposit-confirmation.c b/src/auditor/taler-auditor-httpd_deposit-confirmation.c
index 67bac1b79..08a781f30 100644
--- a/src/auditor/taler-auditor-httpd_deposit-confirmation.c
+++ b/src/auditor/taler-auditor-httpd_deposit-confirmation.c
@@ -111,10 +111,13 @@ verify_and_execute_deposit_confirmation (
   {
     /* Not in cache, need to verify the signature, persist it, and possibly cache it */
     if (GNUNET_OK !=
-        GNUNET_CRYPTO_eddsa_verify (TALER_SIGNATURE_MASTER_SIGNING_KEY_VALIDITY,
-                                    &skv,
-                                    &es->master_sig.eddsa_signature,
-                                    &es->master_public_key.eddsa_pub))
+        TALER_exchange_offline_signkey_validity_verify (
+          &es->exchange_pub,
+          es->ep_start,
+          es->ep_expire,
+          es->ep_end,
+          &es->master_public_key,
+          &es->master_sig))
     {
       TALER_LOG_WARNING ("Invalid signature on exchange signing key\n");
       return TALER_MHD_reply_with_error (connection,
diff --git a/src/auditor/taler-helper-auditor-aggregation.c b/src/auditor/taler-helper-auditor-aggregation.c
index e3e840e8e..f3f65ffb3 100644
--- a/src/auditor/taler-helper-auditor-aggregation.c
+++ b/src/auditor/taler-helper-auditor-aggregation.c
@@ -944,25 +944,15 @@ get_wire_fee (struct AggregationContext *ac,
      easily make this one up, but it means that we have proof that the master
      key was used for inconsistent wire fees if a merchant complains.) */
   {
-    struct TALER_MasterWireFeePS wf = {
-      .purpose.purpose = htonl (TALER_SIGNATURE_MASTER_WIRE_FEES),
-      .purpose.size = htonl (sizeof (wf)),
-      .start_date = GNUNET_TIME_absolute_hton (wfi->start_date),
-      .end_date = GNUNET_TIME_absolute_hton (wfi->end_date)
-    };
-
-    GNUNET_CRYPTO_hash (method,
-                        strlen (method) + 1,
-                        &wf.h_wire_method);
-    TALER_amount_hton (&wf.wire_fee,
-                       &wfi->wire_fee);
-    TALER_amount_hton (&wf.closing_fee,
-                       &wfi->closing_fee);
     if (GNUNET_OK !=
-        GNUNET_CRYPTO_eddsa_verify (TALER_SIGNATURE_MASTER_WIRE_FEES,
-                                    &wf,
-                                    &master_sig.eddsa_signature,
-                                    &TALER_ARL_master_pub.eddsa_pub))
+        TALER_exchange_offline_wire_fee_verify (
+          method,
+          wfi->start_date,
+          wfi->end_date,
+          &wfi->wire_fee,
+          &wfi->closing_fee,
+          &TALER_ARL_master_pub,
+          &master_sig))
     {
       report_row_inconsistency ("wire-fee",
                                 timestamp.abs_value_us,
diff --git a/src/auditor/taler-helper-auditor-coins.c b/src/auditor/taler-helper-auditor-coins.c
index 067d6703a..55feeec36 100644
--- a/src/auditor/taler-helper-auditor-coins.c
+++ b/src/auditor/taler-helper-auditor-coins.c
@@ -715,19 +715,11 @@ init_denomination (const struct GNUNET_HashCode *denom_hash,
   if (0 < qs)
   {
     /* check revocation signature */
-    struct TALER_MasterDenominationKeyRevocationPS rm = {
-      .purpose.purpose = htonl (
-        TALER_SIGNATURE_MASTER_DENOMINATION_KEY_REVOKED),
-      .purpose.size = htonl (sizeof (rm)),
-      .h_denom_pub = *denom_hash
-    };
-
     if (GNUNET_OK !=
-        GNUNET_CRYPTO_eddsa_verify (
-          TALER_SIGNATURE_MASTER_DENOMINATION_KEY_REVOKED,
-          &rm,
-          &msig.eddsa_signature,
-          &TALER_ARL_master_pub.eddsa_pub))
+        TALER_exchange_offline_denomination_revoke_verify (
+          denom_hash,
+          &TALER_ARL_master_pub,
+          &msig))
     {
       report_row_inconsistency ("denomination revocations",
                                 rowid,
diff --git a/src/auditor/taler-helper-auditor-reserves.c b/src/auditor/taler-helper-auditor-reserves.c
index d666aae85..8f7921fa8 100644
--- a/src/auditor/taler-helper-auditor-reserves.c
+++ b/src/auditor/taler-helper-auditor-reserves.c
@@ -747,20 +747,11 @@ handle_recoup_by_reserve (
     }
     else
     {
-      /* verify msig */
-      struct TALER_MasterDenominationKeyRevocationPS kr = {
-        .purpose.purpose = htonl (
-          TALER_SIGNATURE_MASTER_DENOMINATION_KEY_REVOKED),
-        .purpose.size = htonl (sizeof (kr)),
-        .h_denom_pub = coin->denom_pub_hash
-      };
-
       if (GNUNET_OK !=
-          GNUNET_CRYPTO_eddsa_verify (
-            TALER_SIGNATURE_MASTER_DENOMINATION_KEY_REVOKED,
-            &kr,
-            &msig.eddsa_signature,
-            &TALER_ARL_master_pub.eddsa_pub))
+          TALER_exchange_offline_denomination_revoke_verify (
+            &coin->denom_pub_hash,
+            &TALER_ARL_master_pub,
+            &msig))
       {
         rev = "master signature invalid";
       }
diff --git a/src/exchange-tools/taler-exchange-offline.c b/src/exchange-tools/taler-exchange-offline.c
index a33b09eab..506bb9afb 100644
--- a/src/exchange-tools/taler-exchange-offline.c
+++ b/src/exchange-tools/taler-exchange-offline.c
@@ -574,7 +574,9 @@ do_revoke_denomination_key (char *const *args)
   if (GNUNET_OK !=
       load_offline_key ())
     return;
-  // FIXME: do sign, create master_sig!
+  TALER_exchange_offline_denomination_revoke_sign (&h_denom_pub,
+                                                   &master_priv,
+                                                   &master_sig);
   output_operation ("revoke-denomination",
                     json_pack ("{s:o, s:o}",
                                "h_denom_pub",
diff --git a/src/exchange/taler-exchange-httpd_management_denominations_HDP_revoke.c b/src/exchange/taler-exchange-httpd_management_denominations_HDP_revoke.c
index eade5cd1a..75ce3d76b 100644
--- a/src/exchange/taler-exchange-httpd_management_denominations_HDP_revoke.c
+++ b/src/exchange/taler-exchange-httpd_management_denominations_HDP_revoke.c
@@ -56,28 +56,18 @@ TEH_handler_management_denominations_HDP_revoke (
     if (GNUNET_NO == res)
       return MHD_YES; /* failure */
   }
+  if (GNUNET_OK !=
+      TALER_exchange_offline_denomination_revoke_verify (
+        h_denom_pub,
+        &TEH_master_public_key,
+        &master_sig))
   {
-    struct TALER_MasterDenominationKeyRevocationPS rm = {
-      .purpose.purpose = htonl (
-        TALER_SIGNATURE_MASTER_DENOMINATION_KEY_REVOKED),
-      .purpose.size = htonl (sizeof (rm)),
-      .h_denom_pub = *h_denom_pub
-    };
-
-    if (GNUNET_OK !=
-        GNUNET_CRYPTO_eddsa_verify (
-          TALER_SIGNATURE_MASTER_DENOMINATION_KEY_REVOKED,
-          &rm,
-          &master_sig.eddsa_signature,
-          &TEH_master_public_key.eddsa_pub))
-    {
-      GNUNET_break_op (0);
-      return TALER_MHD_reply_with_error (
-        connection,
-        MHD_HTTP_FORBIDDEN,
-        TALER_EC_EXCHANGE_MANAGEMENT_DENOMINATION_REVOKE_SIGNATURE_INVALID,
-        NULL);
-    }
+    GNUNET_break_op (0);
+    return TALER_MHD_reply_with_error (
+      connection,
+      MHD_HTTP_FORBIDDEN,
+      TALER_EC_EXCHANGE_MANAGEMENT_DENOMINATION_REVOKE_SIGNATURE_INVALID,
+      NULL);
   }
   qs = TEH_plugin->insert_denomination_revocation (TEH_plugin->cls,
                                                    NULL,
diff --git a/src/exchange/taler-exchange-httpd_management_post_keys.c b/src/exchange/taler-exchange-httpd_management_post_keys.c
index 2ac69a1db..43ca5f8c4 100644
--- a/src/exchange/taler-exchange-httpd_management_post_keys.c
+++ b/src/exchange/taler-exchange-httpd_management_post_keys.c
@@ -269,23 +269,15 @@ add_keys (void *cls,
 
     /* check signature is valid */
     {
-      struct TALER_ExchangeSigningKeyValidityPS skv = {
-        .purpose.purpose = htonl (
-          TALER_SIGNATURE_MASTER_SIGNING_KEY_VALIDITY),
-        .purpose.size = htonl (sizeof (skv)),
-        .master_public_key = TEH_master_public_key,
-        .start = x,
-        .expire = y,
-        .end = z,
-        .signkey_pub = akc->s_sigs[i].exchange_pub
-      };
-
       if (GNUNET_OK !=
-          GNUNET_CRYPTO_eddsa_verify (
-            TALER_SIGNATURE_MASTER_SIGNING_KEY_VALIDITY,
-            &skv,
-            &akc->s_sigs[i].master_sig.eddsa_signature,
-            &TEH_master_public_key.eddsa_pub))
+          TALER_exchange_offline_signkey_validity_verify (
+            &akc->s_sigs[i].exchange_pub,
+            x,
+            y,
+            z,
+            &TEH_master_public_key,
+            &
+            & akc->s_sigs[i].master_sig))
       {
         GNUNET_break_op (0);
         return TALER_MHD_reply_with_error (
diff --git a/src/exchange/taler-exchange-httpd_management_signkey_EP_revoke.c b/src/exchange/taler-exchange-httpd_management_signkey_EP_revoke.c
index 63a4f0c65..8a462f967 100644
--- a/src/exchange/taler-exchange-httpd_management_signkey_EP_revoke.c
+++ b/src/exchange/taler-exchange-httpd_management_signkey_EP_revoke.c
@@ -56,28 +56,17 @@ TEH_handler_management_signkeys_EP_revoke (
     if (GNUNET_NO == res)
       return MHD_YES; /* failure */
   }
+  if (GNUNET_OK !=
+      TALER_exchange_offline_signkey_revoke_verify (exchange_pub,
+                                                    &TEH_master_public_key,
+                                                    &master_sig))
   {
-    struct TALER_MasterSigningKeyRevocationPS rm = {
-      .purpose.purpose = htonl (
-        TALER_SIGNATURE_MASTER_SIGNING_KEY_REVOKED),
-      .purpose.size = htonl (sizeof (rm)),
-      .exchange_pub = *exchange_pub
-    };
-
-    if (GNUNET_OK !=
-        GNUNET_CRYPTO_eddsa_verify (
-          TALER_SIGNATURE_MASTER_SIGNING_KEY_REVOKED,
-          &rm,
-          &master_sig.eddsa_signature,
-          &TEH_master_public_key.eddsa_pub))
-    {
-      GNUNET_break_op (0);
-      return TALER_MHD_reply_with_error (
-        connection,
-        MHD_HTTP_FORBIDDEN,
-        TALER_EC_EXCHANGE_MANAGEMENT_SIGNKEY_REVOKE_SIGNATURE_INVALID,
-        NULL);
-    }
+    GNUNET_break_op (0);
+    return TALER_MHD_reply_with_error (
+      connection,
+      MHD_HTTP_FORBIDDEN,
+      TALER_EC_EXCHANGE_MANAGEMENT_SIGNKEY_REVOKE_SIGNATURE_INVALID,
+      NULL);
   }
   qs = TEH_plugin->insert_signkey_revocation (TEH_plugin->cls,
                                               NULL,
diff --git a/src/exchange/taler-exchange-httpd_management_wire.c b/src/exchange/taler-exchange-httpd_management_wire.c
index 2ec42c3bc..15e5b3610 100644
--- a/src/exchange/taler-exchange-httpd_management_wire.c
+++ b/src/exchange/taler-exchange-httpd_management_wire.c
@@ -168,29 +168,18 @@ TEH_handler_management_denominations_wire (
     if (GNUNET_NO == res)
       return MHD_YES; /* failure */
   }
+  if (GNUNET_OK !=
+      TALER_exchange_offline_wire_add_verify (awc.payto_uri,
+                                              awc.validity_start,
+                                              &TEH_master_public_key,
+                                              &awc.master_sig_add))
   {
-    struct TALER_MasterAddWirePS aw = {
-      .purpose.purpose = htonl (TALER_SIGNATURE_MASTER_ADD_WIRE),
-      .purpose.size = htonl (sizeof (aw)),
-      .start_date = GNUNET_TIME_absolute_hton (awc.validity_start),
-    };
-
-    TALER_exchange_wire_signature_hash (awc.payto_uri,
-                                        &aw.h_wire);
-    if (GNUNET_OK !=
-        GNUNET_CRYPTO_eddsa_verify (
-          TALER_SIGNATURE_MASTER_ADD_WIRE,
-          &aw,
-          &awc.master_sig_add.eddsa_signature,
-          &TEH_master_public_key.eddsa_pub))
-    {
-      GNUNET_break_op (0);
-      return TALER_MHD_reply_with_error (
-        connection,
-        MHD_HTTP_FORBIDDEN,
-        TALER_EC_EXCHANGE_MANAGEMENT_WIRE_ADD_SIGNATURE_INVALID,
-        NULL);
-    }
+    GNUNET_break_op (0);
+    return TALER_MHD_reply_with_error (
+      connection,
+      MHD_HTTP_FORBIDDEN,
+      TALER_EC_EXCHANGE_MANAGEMENT_WIRE_ADD_SIGNATURE_INVALID,
+      NULL);
   }
   if (GNUNET_OK !=
       TALER_exchange_wire_signature_check (awc.payto_uri,
diff --git a/src/exchange/taler-exchange-httpd_management_wire_disable.c b/src/exchange/taler-exchange-httpd_management_wire_disable.c
index af5942a1b..51b811604 100644
--- a/src/exchange/taler-exchange-httpd_management_wire_disable.c
+++ b/src/exchange/taler-exchange-httpd_management_wire_disable.c
@@ -161,30 +161,19 @@ TEH_handler_management_denominations_wire_disable (
     if (GNUNET_NO == res)
       return MHD_YES; /* failure */
   }
+  if (GNUNET_OK !=
+      TALER_exchange_offline_wire_del_verify (
+        awc.payto_uri,
+        awc.validity_end,
+        &TEH_master_public_key,
+        &awc.master_sig))
   {
-    struct TALER_MasterDelWirePS aw = {
-      .purpose.purpose = htonl (
-        TALER_SIGNATURE_MASTER_DEL_WIRE),
-      .purpose.size = htonl (sizeof (aw)),
-      .end_date = GNUNET_TIME_absolute_hton (awc.validity_end),
-    };
-
-    TALER_exchange_wire_signature_hash (awc.payto_uri,
-                                        &aw.h_wire);
-    if (GNUNET_OK !=
-        GNUNET_CRYPTO_eddsa_verify (
-          TALER_SIGNATURE_MASTER_DEL_WIRE,
-          &aw,
-          &awc.master_sig.eddsa_signature,
-          &TEH_master_public_key.eddsa_pub))
-    {
-      GNUNET_break_op (0);
-      return TALER_MHD_reply_with_error (
-        connection,
-        MHD_HTTP_FORBIDDEN,
-        TALER_EC_EXCHANGE_MANAGEMENT_WIRE_DEL_SIGNATURE_INVALID,
-        NULL);
-    }
+    GNUNET_break_op (0);
+    return TALER_MHD_reply_with_error (
+      connection,
+      MHD_HTTP_FORBIDDEN,
+      TALER_EC_EXCHANGE_MANAGEMENT_WIRE_DEL_SIGNATURE_INVALID,
+      NULL);
   }
   qs = TEH_DB_run_transaction (connection,
                                "del wire",
diff --git a/src/exchange/taler-exchange-httpd_management_wire_fees.c b/src/exchange/taler-exchange-httpd_management_wire_fees.c
index 58f2c41d7..9878821c1 100644
--- a/src/exchange/taler-exchange-httpd_management_wire_fees.c
+++ b/src/exchange/taler-exchange-httpd_management_wire_fees.c
@@ -221,36 +221,23 @@ TEH_handler_management_post_wire_fees (
                                        TEH_currency);
   }
 
+  if (GNUNET_OK !=
+      TALER_exchange_offline_wire_fee_verify (
+        afc.wire_method,
+        afc.start_time,
+        afc.end_time,
+        &afc.wire_fee,
+        &afc.closing_fee,
+        &TEH_master_public_key,
+        &afc.master_sig))
   {
-    struct TALER_MasterWireFeePS wf = {
-      .purpose.purpose = htonl (TALER_SIGNATURE_MASTER_WIRE_FEES),
-      .purpose.size = htonl (sizeof (wf)),
-      .start_date = GNUNET_TIME_absolute_hton (afc.start_time),
-      .end_date = GNUNET_TIME_absolute_hton (afc.end_time),
-    };
-
-    TALER_amount_hton (&wf.wire_fee,
-                       &afc.wire_fee);
-    TALER_amount_hton (&wf.closing_fee,
-                       &afc.closing_fee);
-    GNUNET_CRYPTO_hash (afc.wire_method,
-                        strlen (afc.wire_method) + 1,
-                        &wf.h_wire_method);
-    if (GNUNET_OK !=
-        GNUNET_CRYPTO_eddsa_verify (
-          TALER_SIGNATURE_MASTER_WIRE_FEES,
-          &wf,
-          &afc.master_sig.eddsa_signature,
-          &TEH_master_public_key.eddsa_pub))
-    {
-      /* signature invalid */
-      GNUNET_break_op (0);
-      return TALER_MHD_reply_with_error (
-        connection,
-        MHD_HTTP_FORBIDDEN,
-        TALER_EC_EXCHANGE_MANAGEMENT_WIRE_FEE_SIGNATURE_INVALID,
-        NULL);
-    }
+    /* signature invalid */
+    GNUNET_break_op (0);
+    return TALER_MHD_reply_with_error (
+      connection,
+      MHD_HTTP_FORBIDDEN,
+      TALER_EC_EXCHANGE_MANAGEMENT_WIRE_FEE_SIGNATURE_INVALID,
+      NULL);
   }
 
   qs = TEH_DB_run_transaction (connection,
diff --git a/src/exchangedb/exchangedb_denomkeys.c b/src/exchangedb/exchangedb_denomkeys.c
index ec77d7f0b..81828aaee 100644
--- a/src/exchangedb/exchangedb_denomkeys.c
+++ b/src/exchangedb/exchangedb_denomkeys.c
@@ -22,6 +22,7 @@
  * @author Christian Grothoff
  */
 #include "platform.h"
+#include "taler_crypto_lib.h"
 #include "taler_exchangedb_lib.h"
 
 
@@ -67,18 +68,9 @@ TALER_EXCHANGEDB_denomination_key_revoke (
   int ret;
   struct RevocationFileP rd;
 
-  {
-    struct TALER_MasterDenominationKeyRevocationPS rm = {
-      .purpose.purpose = htonl (
-        TALER_SIGNATURE_MASTER_DENOMINATION_KEY_REVOKED),
-      .purpose.size = htonl (sizeof (rm)),
-      .h_denom_pub = *denom_hash
-    };
-
-    GNUNET_CRYPTO_eddsa_sign (&mpriv->eddsa_priv,
-                              &rm,
-                              &rd.msig.eddsa_signature);
-  }
+  TALER_exchange_offline_denomination_revoke_sign (denom_hash,
+                                                   mpriv,
+                                                   &rd.msig);
   GNUNET_asprintf (&fn,
                    "%s" DIR_SEPARATOR_STR
                    "%s.rev",
@@ -464,34 +456,24 @@ revocations_iterate_cb (void *cls,
     return GNUNET_OK;
   }
 
+  if (GNUNET_OK !=
+      TALER_exchange_offline_denomination_revoke_verify (
+        &rf.denom_hash,
+        ric->master_pub,
+        &rf.msig))
   {
-    struct TALER_MasterDenominationKeyRevocationPS rm = {
-      .purpose.purpose = htonl (
-        TALER_SIGNATURE_MASTER_DENOMINATION_KEY_REVOKED),
-      .purpose.size = htonl (sizeof (rm)),
-      .h_denom_pub = rf.denom_hash
-    };
-
-    if (GNUNET_OK !=
-        GNUNET_CRYPTO_eddsa_verify (
-          TALER_SIGNATURE_MASTER_DENOMINATION_KEY_REVOKED,
-          &rm,
-          &rf.msig.eddsa_signature,
-          &ric->master_pub->eddsa_pub))
-    {
-      GNUNET_log (GNUNET_ERROR_TYPE_ERROR,
-                  "Invalid revocation file `%s' found and ignored (bad signature)\n",
-                  filename);
-      return GNUNET_OK;
-    }
-
-    GNUNET_log (GNUNET_ERROR_TYPE_DEBUG,
-                "Denomination key `%s' was revoked!\n",
-                GNUNET_h2s (&rm.h_denom_pub));
-    return ric->it (ric->it_cls,
-                    &rm.h_denom_pub,
-                    &rf.msig);
+    GNUNET_log (GNUNET_ERROR_TYPE_ERROR,
+                "Invalid revocation file `%s' found and ignored (bad signature)\n",
+                filename);
+    return GNUNET_OK;
   }
+
+  GNUNET_log (GNUNET_ERROR_TYPE_DEBUG,
+              "Denomination key `%s' was revoked!\n",
+              GNUNET_h2s (&rf.denom_hash));
+  return ric->it (ric->it_cls,
+                  &rf.denom_hash,
+                  &rf.msig);
 }
 
 
diff --git a/src/include/taler_crypto_lib.h b/src/include/taler_crypto_lib.h
index 5e50ddd3f..8203bb9af 100644
--- a/src/include/taler_crypto_lib.h
+++ b/src/include/taler_crypto_lib.h
@@ -1050,10 +1050,222 @@ TALER_CRYPTO_helper_esign_disconnect (
   struct TALER_CRYPTO_ExchangeSignHelper *esh);
 
 
+/* ********************* offline signing ************************** */
+
+/**
+ * Create denomination revocation signature.
+ *
+ * @param h_denom_pub hash of public denomination key to revoke
+ * @param master_priv private key to sign with
+ * @param[out] master_sig where to write the signature
+ */
+void
+TALER_exchange_offline_denomination_revoke_sign (
+  const struct GNUNET_HashCode *h_denom_pub,
+  const struct TALER_MasterPrivateKeyP *master_priv,
+  struct TALER_MasterSignatureP *master_sig);
+
+
+/**
+ * Verify denomination revocation signature.
+ *
+ * @param h_denom_pub hash of public denomination key to revoke
+ * @param master_pub public key to verify against
+ * @param master_sig the signature the signature
+ * @return #GNUNET_OK if the signature is valid
+ */
+int
+TALER_exchange_offline_denomination_revoke_verify (
+  const struct GNUNET_HashCode *h_denom_pub,
+  const struct TALER_MasterPublicKeyP *master_pub,
+  const struct TALER_MasterSignatureP *master_sig);
+
+
+/**
+ * Create signkey revocation signature.
+ *
+ * @param exchange_pub public signing key to revoke
+ * @param master_priv private key to sign with
+ * @param[out] master_sig where to write the signature
+ */
+void
+TALER_exchange_offline_signkey_revoke_sign (
+  const struct TALER_ExchangePublicKeyP *exchange_pub,
+  const struct TALER_MasterPrivateKeyP *master_priv,
+  struct TALER_MasterSignatureP *master_sig);
+
+
+/**
+ * Verify signkey revocation signature.
+ *
+ * @param exchange_pub public signkey key to revoke
+ * @param master_pub public key to verify against
+ * @param master_sig the signature the signature
+ * @return #GNUNET_OK if the signature is valid
+ */
+int
+TALER_exchange_offline_signkey_revoke_verify (
+  const struct TALER_ExchangePublicKeyP *exchange_pub,
+  const struct TALER_MasterPublicKeyP *master_pub,
+  const struct TALER_MasterSignatureP *master_sig);
+
+
+/**
+ * Create signkey validity signature.
+ *
+ * @param exchange_pub public signing key to validate
+ * @param start_sign starting point of validity for signing
+ * @param end_sign end point (exclusive) for validity for signing
+ * @param end_legal legal end point of signature validity
+ * @param master_priv private key to sign with
+ * @param[out] master_sig where to write the signature
+ */
+void
+TALER_exchange_offline_signkey_validity_sign (
+  const struct TALER_ExchangePublicKeyP *exchange_pub,
+  struct GNUNET_TIME_Absolute start_sign,
+  struct GNUNET_TIME_Absolute end_sign,
+  struct GNUNET_TIME_Absolute end_legal,
+  const struct TALER_MasterPrivateKeyP *master_priv,
+  struct TALER_MasterSignatureP *master_sig);
+
+
+/**
+ * Verify signkey validitity signature.
+ *
+ * @param exchange_pub public signkey key to validate
+ * @param start_sign starting point of validity for signing
+ * @param end_sign end point (exclusive) for validity for signing
+ * @param end_legal legal end point of signature validity
+ * @param master_pub public key to verify against
+ * @param master_sig the signature the signature
+ * @return #GNUNET_OK if the signature is valid
+ */
+int
+TALER_exchange_offline_signkey_validity_verify (
+  const struct TALER_ExchangePublicKeyP *exchange_pub,
+  struct GNUNET_TIME_Absolute start_sign,
+  struct GNUNET_TIME_Absolute end_sign,
+  struct GNUNET_TIME_Absolute end_legal,
+  const struct TALER_MasterPublicKeyP *master_pub,
+  const struct TALER_MasterSignatureP *master_sig);
+
+
 /* **************** /wire account offline signing **************** */
 
 
 /**
+ * Create wire fee signature.
+ *
+ * @param payment_method the payment method
+ * @param start_time when do the fees start to apply
+ * @param end_time when do the fees start to apply
+ * @param wire_fee the wire fee
+ * @param closing_fee the closing fee
+ * @param master_priv private key to sign with
+ * @param[out] master_sig where to write the signature
+ */
+void
+TALER_exchange_offline_wire_fee_sign (
+  const char *payment_method,
+  struct GNUNET_TIME_Absolute start_time,
+  struct GNUNET_TIME_Absolute end_time,
+  const struct TALER_Amount *wire_fee,
+  const struct TALER_Amount *closing_fee,
+  const struct TALER_MasterPrivateKeyP *master_priv,
+  struct TALER_MasterSignatureP *master_sig);
+
+
+/**
+ * Verify wire fee signature.
+ *
+ * @param payment_method the payment method
+ * @param start_time when do the fees start to apply
+ * @param end_time when do the fees start to apply
+ * @param wire_fee the wire fee
+ * @param closing_fee the closing fee
+ * @param master_pub public key to verify against
+ * @param master_sig the signature the signature
+ * @return #GNUNET_OK if the signature is valid
+ */
+int
+TALER_exchange_offline_wire_fee_verify (
+  const char *payment_method,
+  struct GNUNET_TIME_Absolute start_time,
+  struct GNUNET_TIME_Absolute end_time,
+  const struct TALER_Amount *wire_fee,
+  const struct TALER_Amount *closing_fee,
+  const struct TALER_MasterPublicKeyP *master_pub,
+  const struct TALER_MasterSignatureP *master_sig);
+
+
+/**
+ * Create wire account addition signature.
+ *
+ * @param payto_uri bank account
+ * @param now timestamp to use for the signature (rounded)
+ * @param master_priv private key to sign with
+ * @param[out] master_sig where to write the signature
+ */
+void
+TALER_exchange_offline_wire_add_sign (
+  const char *payto_uri,
+  struct GNUNET_TIME_Absolute now,
+  const struct TALER_MasterPrivateKeyP *master_priv,
+  struct TALER_MasterSignatureP *master_sig);
+
+
+/**
+ * Verify wire account addition signature.
+ *
+ * @param payto_uri bank account
+ * @param sign_time timestamp when signature was created
+ * @param master_pub public key to verify against
+ * @param master_sig the signature the signature
+ * @return #GNUNET_OK if the signature is valid
+ */
+int
+TALER_exchange_offline_wire_add_verify (
+  const char *payto_uri,
+  struct GNUNET_TIME_Absolute sign_time,
+  const struct TALER_MasterPublicKeyP *master_pub,
+  const struct TALER_MasterSignatureP *master_sig);
+
+
+/**
+ * Create wire account removal signature.
+ *
+ * @param payto_uri bank account
+ * @param now timestamp to use for the signature (rounded)
+ * @param master_priv private key to sign with
+ * @param[out] master_sig where to write the signature
+ */
+void
+TALER_exchange_offline_wire_del_sign (
+  const char *payto_uri,
+  struct GNUNET_TIME_Absolute now,
+  const struct TALER_MasterPrivateKeyP *master_priv,
+  struct TALER_MasterSignatureP *master_sig);
+
+
+/**
+ * Verify wire account deletion signature.
+ *
+ * @param payto_uri bank account
+ * @param sign_time timestamp when signature was created
+ * @param master_pub public key to verify against
+ * @param master_sig the signature the signature
+ * @return #GNUNET_OK if the signature is valid
+ */
+int
+TALER_exchange_offline_wire_del_verify (
+  const char *payto_uri,
+  struct GNUNET_TIME_Absolute sign_time,
+  const struct TALER_MasterPublicKeyP *master_pub,
+  const struct TALER_MasterSignatureP *master_sig);
+
+
+/**
  * Compute the hash of the given wire details.   The resulting
  * hash is what is signed by the master key.
  *
@@ -1068,7 +1280,7 @@ TALER_exchange_wire_signature_hash (const char *payto_uri,
 /**
  * Check the signature in @a master_sig.
  *
- * @param payto_uri URL that is signed
+ * @param payto_uri URI that is signed
  * @param master_pub master public key of the exchange
  * @param master_sig signature of the exchange
  * @return #GNUNET_OK if signature is valid
diff --git a/src/lib/auditor_api_deposit_confirmation.c b/src/lib/auditor_api_deposit_confirmation.c
index ff65036e0..bea5a78a5 100644
--- a/src/lib/auditor_api_deposit_confirmation.c
+++ b/src/lib/auditor_api_deposit_confirmation.c
@@ -208,27 +208,18 @@ verify_signatures (const struct GNUNET_HashCode *h_wire,
       return GNUNET_SYSERR;
     }
   }
+  if (GNUNET_OK !=
+      TALER_exchange_offline_signkey_validity_verify (
+        exchange_pub,
+        ep_start,
+        ep_expire,
+        ep_end,
+        master_pub,
+        master_sig))
   {
-    struct TALER_ExchangeSigningKeyValidityPS sv = {
-      .purpose.purpose = htonl (TALER_SIGNATURE_MASTER_SIGNING_KEY_VALIDITY),
-      .purpose.size = htonl (sizeof (sv)),
-      .master_public_key = *master_pub,
-      .start = GNUNET_TIME_absolute_hton (ep_start),
-      .expire = GNUNET_TIME_absolute_hton (ep_expire),
-      .end = GNUNET_TIME_absolute_hton (ep_end),
-      .signkey_pub = *exchange_pub
-    };
-
-    if (GNUNET_OK !=
-        GNUNET_CRYPTO_eddsa_verify (TALER_SIGNATURE_MASTER_SIGNING_KEY_VALIDITY,
-                                    &sv,
-                                    &master_sig->eddsa_signature,
-                                    &master_pub->eddsa_pub))
-    {
-      GNUNET_break (0);
-      TALER_LOG_WARNING ("Invalid signature on exchange signing key!\n");
-      return GNUNET_SYSERR;
-    }
+    GNUNET_break (0);
+    TALER_LOG_WARNING ("Invalid signature on exchange signing key!\n");
+    return GNUNET_SYSERR;
   }
   if (0 == GNUNET_TIME_absolute_get_remaining (ep_end).rel_value_us)
   {
diff --git a/src/lib/exchange_api_handle.c b/src/lib/exchange_api_handle.c
index 4d8f0d037..ed6093556 100644
--- a/src/lib/exchange_api_handle.c
+++ b/src/lib/exchange_api_handle.c
@@ -394,26 +394,17 @@ parse_json_signkey (struct TALER_EXCHANGE_SigningPublicKey *sign_key,
 
   if (! check_sigs)
     return GNUNET_OK;
+  if (GNUNET_OK !=
+      TALER_exchange_offline_signkey_validity_verify
+        (&sign_key->key,
+        sign_key->valid_from,
+        sign_key->valid_until,
+        sign_key->valid_legal,
+        master_key,
+        &sign_key_issue_sig))
   {
-    struct TALER_ExchangeSigningKeyValidityPS sign_key_issue = {
-      .purpose.purpose = htonl (TALER_SIGNATURE_MASTER_SIGNING_KEY_VALIDITY),
-      .purpose.size = htonl (sizeof (sign_key_issue)),
-      .signkey_pub = sign_key->key,
-      .master_public_key = *master_key,
-      .start = GNUNET_TIME_absolute_hton (sign_key->valid_from),
-      .expire = GNUNET_TIME_absolute_hton (sign_key->valid_until),
-      .end = GNUNET_TIME_absolute_hton (sign_key->valid_legal)
-    };
-
-    if (GNUNET_OK !=
-        GNUNET_CRYPTO_eddsa_verify (TALER_SIGNATURE_MASTER_SIGNING_KEY_VALIDITY,
-                                    &sign_key_issue,
-                                    &sign_key_issue_sig.eddsa_signature,
-                                    &master_key->eddsa_pub))
-    {
-      GNUNET_break_op (0);
-      return GNUNET_SYSERR;
-    }
+    GNUNET_break_op (0);
+    return GNUNET_SYSERR;
   }
   sign_key->master_sig = sign_key_issue_sig;
   return GNUNET_OK;
diff --git a/src/testing/testing_api_cmd_revoke_denom_key.c b/src/testing/testing_api_cmd_revoke_denom_key.c
index 7dffcf395..fd7695bce 100644
--- a/src/testing/testing_api_cmd_revoke_denom_key.c
+++ b/src/testing/testing_api_cmd_revoke_denom_key.c
@@ -187,16 +187,9 @@ revoke_run (void *cls,
   }
   else
   {
-    struct TALER_MasterDenominationKeyRevocationPS kv = {
-      .purpose.purpose = htonl (
-        TALER_SIGNATURE_MASTER_DENOMINATION_KEY_REVOKED),
-      .purpose.size = htonl (sizeof (kv)),
-      .h_denom_pub = denom_pub->h_key
-    };
-
-    GNUNET_CRYPTO_eddsa_sign (&is->master_priv.eddsa_priv,
-                              &kv,
-                              &master_sig.eddsa_signature);
+    TALER_exchange_offline_denomination_revoke_sign (&denom_pub->h_key,
+                                                     &is->master_priv,
+                                                     &master_sig);
   }
   rs->kh = TALER_EXCHANGE_management_revoke_denomination_key (
     is->ctx,
diff --git a/src/testing/testing_api_cmd_revoke_sign_key.c b/src/testing/testing_api_cmd_revoke_sign_key.c
index d85f63053..599fe180b 100644
--- a/src/testing/testing_api_cmd_revoke_sign_key.c
+++ b/src/testing/testing_api_cmd_revoke_sign_key.c
@@ -187,16 +187,9 @@ revoke_run (void *cls,
   }
   else
   {
-    struct TALER_MasterSigningKeyRevocationPS kv = {
-      .purpose.purpose = htonl (
-        TALER_SIGNATURE_MASTER_SIGNING_KEY_REVOKED),
-      .purpose.size = htonl (sizeof (kv)),
-      .exchange_pub = *exchange_pub
-    };
-
-    GNUNET_CRYPTO_eddsa_sign (&is->master_priv.eddsa_priv,
-                              &kv,
-                              &master_sig.eddsa_signature);
+    TALER_exchange_offline_signkey_revoke_sign (exchange_pub,
+                                                &is->master_priv,
+                                                &master_sig);
   }
   rs->kh = TALER_EXCHANGE_management_revoke_signing_key (
     is->ctx,
diff --git a/src/testing/testing_api_cmd_set_wire_fee.c b/src/testing/testing_api_cmd_set_wire_fee.c
index 1f8b3994a..613e0f713 100644
--- a/src/testing/testing_api_cmd_set_wire_fee.c
+++ b/src/testing/testing_api_cmd_set_wire_fee.c
@@ -152,23 +152,13 @@ wire_add_run (void *cls,
   }
   else
   {
-    struct TALER_MasterWireFeePS kv = {
-      .purpose.purpose = htonl (TALER_SIGNATURE_MASTER_WIRE_FEES),
-      .purpose.size = htonl (sizeof (kv)),
-      .start_date = GNUNET_TIME_absolute_hton (start_time),
-      .end_date = GNUNET_TIME_absolute_hton (end_time),
-    };
-
-    GNUNET_CRYPTO_hash (ds->wire_method,
-                        strlen (ds->wire_method) + 1,
-                        &kv.h_wire_method);
-    TALER_amount_hton (&kv.wire_fee,
-                       &wire_fee);
-    TALER_amount_hton (&kv.closing_fee,
-                       &closing_fee);
-    GNUNET_CRYPTO_eddsa_sign (&is->master_priv.eddsa_priv,
-                              &kv,
-                              &master_sig.eddsa_signature);
+    TALER_exchange_offline_wire_fee_sign (ds->wire_method,
+                                          start_time,
+                                          end_time,
+                                          &wire_fee,
+                                          &closing_fee,
+                                          &is->master_priv,
+                                          &master_sig);
   }
   ds->dh = TALER_EXCHANGE_management_set_wire_fees (
     is->ctx,
diff --git a/src/testing/testing_api_cmd_wire_add.c b/src/testing/testing_api_cmd_wire_add.c
index 6f25a0f86..8d8a3a4f6 100644
--- a/src/testing/testing_api_cmd_wire_add.c
+++ b/src/testing/testing_api_cmd_wire_add.c
@@ -126,17 +126,10 @@ wire_add_run (void *cls,
   }
   else
   {
-    struct TALER_MasterAddWirePS kv = {
-      .purpose.purpose = htonl (TALER_SIGNATURE_MASTER_ADD_WIRE),
-      .purpose.size = htonl (sizeof (kv)),
-      .start_date = GNUNET_TIME_absolute_hton (now),
-    };
-
-    TALER_exchange_wire_signature_hash (ds->payto_uri,
-                                        &kv.h_wire);
-    GNUNET_CRYPTO_eddsa_sign (&is->master_priv.eddsa_priv,
-                              &kv,
-                              &master_sig1.eddsa_signature);
+    TALER_exchange_offline_wire_add_sign (ds->payto_uri,
+                                          now,
+                                          &is->master_priv,
+                                          &master_sig1);
     TALER_exchange_wire_signature_make (ds->payto_uri,
                                         &is->master_priv,
                                         &master_sig2);
diff --git a/src/testing/testing_api_cmd_wire_del.c b/src/testing/testing_api_cmd_wire_del.c
index 2019d1366..2a1c9e455 100644
--- a/src/testing/testing_api_cmd_wire_del.c
+++ b/src/testing/testing_api_cmd_wire_del.c
@@ -122,17 +122,10 @@ wire_del_run (void *cls,
   }
   else
   {
-    struct TALER_MasterDelWirePS kv = {
-      .purpose.purpose = htonl (TALER_SIGNATURE_MASTER_DEL_WIRE),
-      .purpose.size = htonl (sizeof (kv)),
-      .end_date = GNUNET_TIME_absolute_hton (now),
-    };
-
-    TALER_exchange_wire_signature_hash (ds->payto_uri,
-                                        &kv.h_wire);
-    GNUNET_CRYPTO_eddsa_sign (&is->master_priv.eddsa_priv,
-                              &kv,
-                              &master_sig.eddsa_signature);
+    TALER_exchange_offline_wire_del_sign (ds->payto_uri,
+                                          now,
+                                          &is->master_priv,
+                                          &master_sig);
   }
   ds->dh = TALER_EXCHANGE_management_disable_wire (
     is->ctx,
diff --git a/src/util/Makefile.am b/src/util/Makefile.am
index 95ac60a96..c65a3ef17 100644
--- a/src/util/Makefile.am
+++ b/src/util/Makefile.am
@@ -68,6 +68,7 @@ libtalerutil_la_SOURCES = \
   getopt.c \
   lang.c \
   mhd.c \
+  offline_signatures.c \
   payto.c \
   taler_error_codes.c \
   url.c \
diff --git a/src/util/offline_signatures.c b/src/util/offline_signatures.c
new file mode 100644
index 000000000..af7876b93
--- /dev/null
+++ b/src/util/offline_signatures.c
@@ -0,0 +1,314 @@
+/*
+  This file is part of TALER
+  Copyright (C) 2020 Taler Systems SA
+
+  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
+  Foundation; either version 3, or (at your option) any later version.
+
+  TALER is distributed in the hope that it will be useful, but WITHOUT ANY
+  WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR
+  A PARTICULAR PURPOSE.  See the GNU General Public License for more details.
+
+  You should have received a copy of the GNU General Public License along with
+  TALER; see the file COPYING.  If not, see <http://www.gnu.org/licenses/>
+*/
+/**
+ * @file offline_signatures.c
+ * @brief Utility functions for Taler exchange offline signatures
+ * @author Christian Grothoff
+ */
+#include "platform.h"
+#include "taler_util.h"
+#include "taler_signatures.h"
+
+
+void
+TALER_exchange_offline_denomination_revoke_sign (
+  const struct GNUNET_HashCode *h_denom_pub,
+  const struct TALER_MasterPrivateKeyP *master_priv,
+  struct TALER_MasterSignatureP *master_sig)
+{
+  struct TALER_MasterDenominationKeyRevocationPS rm = {
+    .purpose.purpose = htonl (TALER_SIGNATURE_MASTER_DENOMINATION_KEY_REVOKED),
+    .purpose.size = htonl (sizeof (rm)),
+    .h_denom_pub = *h_denom_pub
+  };
+
+  GNUNET_CRYPTO_eddsa_sign (&master_priv->eddsa_priv,
+                            &rm,
+                            &master_sig->eddsa_signature);
+}
+
+
+int
+TALER_exchange_offline_denomination_revoke_verify (
+  const struct GNUNET_HashCode *h_denom_pub,
+  const struct TALER_MasterPublicKeyP *master_pub,
+  const struct TALER_MasterSignatureP *master_sig)
+{
+  struct TALER_MasterDenominationKeyRevocationPS kr = {
+    .purpose.purpose = htonl (
+      TALER_SIGNATURE_MASTER_DENOMINATION_KEY_REVOKED),
+    .purpose.size = htonl (sizeof (kr)),
+    .h_denom_pub = *h_denom_pub
+  };
+
+  return GNUNET_CRYPTO_eddsa_verify (
+    TALER_SIGNATURE_MASTER_DENOMINATION_KEY_REVOKED,
+    &kr,
+    &master_sig->eddsa_signature,
+    &master_pub->eddsa_pub);
+}
+
+
+void
+TALER_exchange_offline_signkey_revoke_sign (
+  const struct TALER_ExchangePublicKeyP *exchange_pub,
+  const struct TALER_MasterPrivateKeyP *master_priv,
+  struct TALER_MasterSignatureP *master_sig)
+{
+  struct TALER_MasterSigningKeyRevocationPS kv = {
+    .purpose.purpose = htonl (
+      TALER_SIGNATURE_MASTER_SIGNING_KEY_REVOKED),
+    .purpose.size = htonl (sizeof (kv)),
+    .exchange_pub = *exchange_pub
+  };
+
+  GNUNET_CRYPTO_eddsa_sign (&master_priv->eddsa_priv,
+                            &kv,
+                            &master_sig->eddsa_signature);
+}
+
+
+int
+TALER_exchange_offline_signkey_revoke_verify (
+  const struct TALER_ExchangePublicKeyP *exchange_pub,
+  const struct TALER_MasterPublicKeyP *master_pub,
+  const struct TALER_MasterSignatureP *master_sig)
+{
+  struct TALER_MasterSigningKeyRevocationPS rm = {
+    .purpose.purpose = htonl (
+      TALER_SIGNATURE_MASTER_SIGNING_KEY_REVOKED),
+    .purpose.size = htonl (sizeof (rm)),
+    .exchange_pub = *exchange_pub
+  };
+
+  return GNUNET_CRYPTO_eddsa_verify (
+    TALER_SIGNATURE_MASTER_SIGNING_KEY_REVOKED,
+    &rm,
+    &master_sig->eddsa_signature,
+    &master_pub->eddsa_pub);
+}
+
+
+void
+TALER_exchange_offline_signkey_validity_sign (
+  const struct TALER_ExchangePublicKeyP *exchange_pub,
+  struct GNUNET_TIME_Absolute start_sign,
+  struct GNUNET_TIME_Absolute end_sign,
+  struct GNUNET_TIME_Absolute end_legal,
+  const struct TALER_MasterPrivateKeyP *master_priv,
+  struct TALER_MasterSignatureP *master_sig)
+{
+  struct TALER_ExchangeSigningKeyValidityPS skv = {
+    .purpose.purpose = htonl (
+      TALER_SIGNATURE_MASTER_SIGNING_KEY_VALIDITY),
+    .purpose.size = htonl (sizeof (skv)),
+    .start = GNUNET_TIME_absolute_hton (start_sign),
+    .expire = GNUNET_TIME_absolute_hton (end_sign),
+    .end = GNUNET_TIME_absolute_hton (end_legal),
+    .signkey_pub = *exchange_pub
+  };
+
+  GNUNET_CRYPTO_eddsa_sign (&master_priv->eddsa_priv,
+                            &skv,
+                            &master_sig->eddsa_signature);
+}
+
+
+int
+TALER_exchange_offline_signkey_validity_verify (
+  const struct TALER_ExchangePublicKeyP *exchange_pub,
+  struct GNUNET_TIME_Absolute start_sign,
+  struct GNUNET_TIME_Absolute end_sign,
+  struct GNUNET_TIME_Absolute end_legal,
+  const struct TALER_MasterPublicKeyP *master_pub,
+  const struct TALER_MasterSignatureP *master_sig)
+{
+  struct TALER_ExchangeSigningKeyValidityPS skv = {
+    .purpose.purpose = htonl (
+      TALER_SIGNATURE_MASTER_SIGNING_KEY_VALIDITY),
+    .purpose.size = htonl (sizeof (skv)),
+    .start = GNUNET_TIME_absolute_hton (start_sign),
+    .expire = GNUNET_TIME_absolute_hton (end_sign),
+    .end = GNUNET_TIME_absolute_hton (end_legal),
+    .signkey_pub = *exchange_pub
+  };
+
+  return
+    GNUNET_CRYPTO_eddsa_verify (
+    TALER_SIGNATURE_MASTER_SIGNING_KEY_VALIDITY,
+    &skv,
+    &master_sig->eddsa_signature,
+    &master_pub->eddsa_pub);
+}
+
+
+void
+TALER_exchange_offline_wire_add_sign (
+  const char *payto_uri,
+  struct GNUNET_TIME_Absolute now,
+  const struct TALER_MasterPrivateKeyP *master_priv,
+  struct TALER_MasterSignatureP *master_sig)
+{
+  struct TALER_MasterAddWirePS kv = {
+    .purpose.purpose = htonl (TALER_SIGNATURE_MASTER_ADD_WIRE),
+    .purpose.size = htonl (sizeof (kv)),
+    .start_date = GNUNET_TIME_absolute_hton (now),
+  };
+
+  GNUNET_assert (GNUNET_OK ==
+                 GNUNET_TIME_round_abs (&now));
+  TALER_exchange_wire_signature_hash (payto_uri,
+                                      &kv.h_wire);
+  GNUNET_CRYPTO_eddsa_sign (&master_priv->eddsa_priv,
+                            &kv,
+                            &master_sig->eddsa_signature);
+}
+
+
+int
+TALER_exchange_offline_wire_add_verify (
+  const char *payto_uri,
+  struct GNUNET_TIME_Absolute sign_time,
+  const struct TALER_MasterPublicKeyP *master_pub,
+  const struct TALER_MasterSignatureP *master_sig)
+{
+  struct TALER_MasterAddWirePS aw = {
+    .purpose.purpose = htonl (TALER_SIGNATURE_MASTER_ADD_WIRE),
+    .purpose.size = htonl (sizeof (aw)),
+    .start_date = GNUNET_TIME_absolute_hton (sign_time),
+  };
+
+  TALER_exchange_wire_signature_hash (payto_uri,
+                                      &aw.h_wire);
+  return
+    GNUNET_CRYPTO_eddsa_verify (
+    TALER_SIGNATURE_MASTER_ADD_WIRE,
+    &aw,
+    &master_sig->eddsa_signature,
+    &master_pub->eddsa_pub);
+}
+
+
+void
+TALER_exchange_offline_wire_del_sign (
+  const char *payto_uri,
+  struct GNUNET_TIME_Absolute now,
+  const struct TALER_MasterPrivateKeyP *master_priv,
+  struct TALER_MasterSignatureP *master_sig)
+{
+  struct TALER_MasterDelWirePS kv = {
+    .purpose.purpose = htonl (TALER_SIGNATURE_MASTER_DEL_WIRE),
+    .purpose.size = htonl (sizeof (kv)),
+    .end_date = GNUNET_TIME_absolute_hton (now),
+  };
+
+  GNUNET_assert (GNUNET_OK ==
+                 GNUNET_TIME_round_abs (&now));
+  TALER_exchange_wire_signature_hash (payto_uri,
+                                      &kv.h_wire);
+  GNUNET_CRYPTO_eddsa_sign (&master_priv->eddsa_priv,
+                            &kv,
+                            &master_sig->eddsa_signature);
+}
+
+
+int
+TALER_exchange_offline_wire_del_verify (
+  const char *payto_uri,
+  struct GNUNET_TIME_Absolute sign_time,
+  const struct TALER_MasterPublicKeyP *master_pub,
+  const struct TALER_MasterSignatureP *master_sig)
+{
+  struct TALER_MasterDelWirePS aw = {
+    .purpose.purpose = htonl (
+      TALER_SIGNATURE_MASTER_DEL_WIRE),
+    .purpose.size = htonl (sizeof (aw)),
+    .end_date = GNUNET_TIME_absolute_hton (sign_time),
+  };
+
+  TALER_exchange_wire_signature_hash (payto_uri,
+                                      &aw.h_wire);
+  return GNUNET_CRYPTO_eddsa_verify (
+    TALER_SIGNATURE_MASTER_DEL_WIRE,
+    &aw,
+    &master_sig->eddsa_signature,
+    &master_pub->eddsa_pub);
+}
+
+
+void
+TALER_exchange_offline_wire_fee_sign (
+  const char *payment_method,
+  struct GNUNET_TIME_Absolute start_time,
+  struct GNUNET_TIME_Absolute end_time,
+  const struct TALER_Amount *wire_fee,
+  const struct TALER_Amount *closing_fee,
+  const struct TALER_MasterPrivateKeyP *master_priv,
+  struct TALER_MasterSignatureP *master_sig)
+{
+  struct TALER_MasterWireFeePS kv = {
+    .purpose.purpose = htonl (TALER_SIGNATURE_MASTER_WIRE_FEES),
+    .purpose.size = htonl (sizeof (kv)),
+    .start_date = GNUNET_TIME_absolute_hton (start_time),
+    .end_date = GNUNET_TIME_absolute_hton (end_time),
+  };
+
+  GNUNET_CRYPTO_hash (payment_method,
+                      strlen (payment_method) + 1,
+                      &kv.h_wire_method);
+  TALER_amount_hton (&kv.wire_fee,
+                     wire_fee);
+  TALER_amount_hton (&kv.closing_fee,
+                     closing_fee);
+  GNUNET_CRYPTO_eddsa_sign (&master_priv->eddsa_priv,
+                            &kv,
+                            &master_sig->eddsa_signature);
+}
+
+
+int
+TALER_exchange_offline_wire_fee_verify (
+  const char *payment_method,
+  struct GNUNET_TIME_Absolute start_time,
+  struct GNUNET_TIME_Absolute end_time,
+  const struct TALER_Amount *wire_fee,
+  const struct TALER_Amount *closing_fee,
+  const struct TALER_MasterPublicKeyP *master_pub,
+  const struct TALER_MasterSignatureP *master_sig)
+{
+  struct TALER_MasterWireFeePS wf = {
+    .purpose.purpose = htonl (TALER_SIGNATURE_MASTER_WIRE_FEES),
+    .purpose.size = htonl (sizeof (wf)),
+    .start_date = GNUNET_TIME_absolute_hton (start_time),
+    .end_date = GNUNET_TIME_absolute_hton (end_time)
+  };
+
+  GNUNET_CRYPTO_hash (payment_method,
+                      strlen (payment_method) + 1,
+                      &wf.h_wire_method);
+  TALER_amount_hton (&wf.wire_fee,
+                     wire_fee);
+  TALER_amount_hton (&wf.closing_fee,
+                     closing_fee);
+  return
+    GNUNET_CRYPTO_eddsa_verify (TALER_SIGNATURE_MASTER_WIRE_FEES,
+                                &wf,
+                                &master_sig->eddsa_signature,
+                                &master_pub->eddsa_pub);
+}
+
+
+/* end of offline_signatures.c */
diff --git a/src/util/payto.c b/src/util/payto.c
index 4b2bbf4e3..54072d667 100644
--- a/src/util/payto.c
+++ b/src/util/payto.c
@@ -49,24 +49,25 @@ TALER_payto_get_subject (const char *payto_uri)
 
   do {
     if (0 == strncasecmp (++key,
-			  "subject",
-			  strlen ("subject")))
+                          "subject",
+                          strlen ("subject")))
     {
       value_start = strchr (key,
-	                    (unsigned char) '=');
+                            (unsigned char) '=');
       if (NULL == value_start)
         return NULL;
       value_end = strchrnul (value_start,
-	                     (unsigned char) '&');
+                             (unsigned char) '&');
 
       return GNUNET_strndup (value_start + 1,
-	                     value_end - value_start - 1);
+                             value_end - value_start - 1);
     }
   } while ( (key = strchr (key,
-			 (unsigned char) '&')) );
+                           (unsigned char) '&')) );
   return NULL;
 }
 
+
 /**
  * Obtain the payment method from a @a payto_uri. The
  * format of a payto URI is 'payto://$METHOD/$SOMETHING'.
diff --git a/src/util/test_payto.c b/src/util/test_payto.c
index c809a0396..321e998b7 100644
--- a/src/util/test_payto.c
+++ b/src/util/test_payto.c
@@ -58,7 +58,7 @@ main (int argc,
   r = TALER_payto_get_subject (
     "payto://x-taler-bank/localhost:1080/alice?subject=hello&amount=EUR:1");
   CHECK ("hello",
-	 r);
+         r);
 
   r = TALER_payto_get_subject (
     "payto://x-taler-bank/localhost:1080/alice");