exchange

commit d9fdf50e7263eefa4425e746cfb6a39f66e77ac4
parent 3bb7be6cb8a25984ee6bff2f991690b6a6a08220
Author: Florian Dold <dold@taler.net>
Date:   Mon, 27 Jul 2026 20:43:48 +0200

exchange: add a confidence floor for sanction investigations

Diffstat:
M
src/exchange/taler-exchange-sanctionscheck.c
 | 
30
+++++++++++++++++++++++++++---

1 file changed, 27 insertions(+), 3 deletions(-)
diff --git a/src/exchange/taler-exchange-sanctionscheck.c b/src/exchange/taler-exchange-sanctionscheck.c
@@ -174,12 +174,23 @@ static float freeze_rating_limit = 0.9;
 static float freeze_confidence_limit = 0.9;
 
 /**
- * Rating/confidence threshold that must be passed to begin
- * an investigation.
+ * Threshold on rating/confidence that must be exceeded to begin an
+ * investigation (when the account is not automatically frozen).  A low
+ * confidence relative to the rating raises the ratio, which is intentional:
+ * the less sure the automated match is, the more a human should look.
  */
 static float investigation_limit = 0.9;
 
 /**
+ * Minimum match confidence for an investigation.  This gates the ratio test
+ * above so that near-zero-confidence noise (e.g. a fuzzy match against an
+ * attribute that is not a name at all) does not, via its large ratio, flag
+ * every account.  Optional; defaults to 0 to preserve the historic behaviour
+ * of having no confidence floor.
+ */
+static float investigation_confidence_limit = 0.0;
+
+/**
  * Write @a min_row_id to @a min_row_fd.
  */
 static void
@@ -310,7 +321,8 @@ sanction_cb (void *cls,
     freeze = true;
     investigate = true;
   }
-  else if (rating > (double) investigation_limit * confidence)
+  else if ( (rating > (double) investigation_limit * confidence) &&
+            (confidence > (double) investigation_confidence_limit) )
   {
     investigate = true;
   }
@@ -674,6 +686,18 @@ run (void *cls,
     global_ret = EXIT_NOTCONFIGURED;
     return;
   }
+  if (GNUNET_OK !=
+      GNUNET_CONFIGURATION_get_value_float (cfg,
+                                            "exchange-sanctionscheck",
+                                            "INVESTIGATION_CONFIDENCE_LIMIT",
+                                            &investigation_confidence_limit))
+  {
+    /* Optional; absence restores the historic no-floor behaviour.  It gates
+       every investigation, so say which value is in force. */
+    GNUNET_log (GNUNET_ERROR_TYPE_INFO,
+                "INVESTIGATION_CONFIDENCE_LIMIT not configured, using %f\n",
+                (double) investigation_confidence_limit);
+  }
   if (! init_freeze ())
     return;
   {