exchange

commit e5c34ad587d6e21ed6d6950f1250018e9b3ec274
parent d2f4ff23fb8e50208ab396f6e87e09a7a4fa17a6
Author: Christian Grothoff <christian@grothoff.org>
Date:   Sat, 10 Oct 2026 00:25:00 +0200

refuse exchange changing master key or currency when cherry-picking /keys

Diffstat:
M
src/lib/exchange_api_get-keys.c
 | 
26
++++++++++++++++++++++++++

1 file changed, 26 insertions(+), 0 deletions(-)
diff --git a/src/lib/exchange_api_get-keys.c b/src/lib/exchange_api_get-keys.c
@@ -359,6 +359,32 @@ keys_completed_cb (void *cls,
       kresp.hr.ec = TALER_EC_GENERIC_REPLY_MALFORMED;
       break;
     }
+    if (NULL != gkh->prev_keys)
+    {
+      const struct TALER_EXCHANGE_Keys *kd_old = gkh->prev_keys;
+
+      /* The denominations and auditor signatures we cherry-picked from
+         the previous response were validated against the master public
+         key of that response; refuse to re-attribute them to a
+         different master public key (or currency). */
+      if ( (0 !=
+            GNUNET_memcmp (&kd->master_pub,
+                           &kd_old->master_pub)) ||
+           (0 !=
+            strcmp (kd->currency,
+                    kd_old->currency)) )
+      {
+        GNUNET_break_op (0);
+        TALER_LOG_ERROR (
+          "Exchange changed master public key or currency in /keys\n");
+        kd->rc = 1;
+        TALER_EXCHANGE_keys_decref (kd);
+        kd = NULL;
+        kresp.hr.http_status = 0;
+        kresp.hr.ec = TALER_EC_GENERIC_REPLY_MALFORMED;
+        break;
+      }
+    }
     kd->rc = 1;
     kd->key_data_expiration = gkh->expire;
     if (GNUNET_TIME_relative_cmp (