exchange

commit 12f9e8c08bc8987585e009bcee068a51351d30da
parent abf2f890754bcf1d6c11fc4b2b41adf4c18a70d7
Author: Christian Grothoff <christian@grothoff.org>
Date:   Sun, 11 Oct 2026 14:30:36 +0200

refuse inconsistent age masks

Diffstat:
M
src/exchange/taler-exchange-httpd_post-reveal-withdraw.c
 | 
13
++++++++++++-
M
src/exchange/taler-exchange-httpd_post-withdraw.c
 | 
36
++++++++++++++++++++++++++++++++++++

2 files changed, 48 insertions(+), 1 deletion(-)
diff --git a/src/exchange/taler-exchange-httpd_post-reveal-withdraw.c b/src/exchange/taler-exchange-httpd_post-reveal-withdraw.c
@@ -391,7 +391,18 @@ verify_commitment_and_max_age (
 
     if (i == 0)
       mask = denom_keys[i]->meta.age_mask;
-    GNUNET_assert (mask.bits == denom_keys[i]->meta.age_mask.bits);
+    if (mask.bits != denom_keys[i]->meta.age_mask.bits)
+    {
+      /* /withdraw refuses age-restricted batches with mixed age masks,
+         so such a commitment cannot have been stored by this version. */
+      GNUNET_break (0);
+      *result = TALER_MHD_reply_with_error (
+        con,
+        MHD_HTTP_INTERNAL_SERVER_ERROR,
+        TALER_EC_GENERIC_INTERNAL_INVARIANT_FAILURE,
+        "denominations of the withdraw commitment have different age masks");
+      return GNUNET_SYSERR;
+    }
 
     if (GNUNET_CRYPTO_BSA_CS ==
         denom_keys[i]->denom_pub.bsign_pub_key->cipher)
diff --git a/src/exchange/taler-exchange-httpd_post-withdraw.c b/src/exchange/taler-exchange-httpd_post-withdraw.c
@@ -49,6 +49,7 @@
 enum WithdrawError
 {
   WITHDRAW_ERROR_NONE,
+  WITHDRAW_ERROR_AGE_MASK_MISMATCH,
   WITHDRAW_ERROR_AGE_RESTRICTION_NOT_SUPPORTED_BY_DENOMINATION,
   WITHDRAW_ERROR_AGE_RESTRICTION_REQUIRED,
   WITHDRAW_ERROR_AMOUNT_OVERFLOW,
@@ -257,6 +258,7 @@ struct WithdrawContext
        *  WITHDRAW_ERROR_DENOMINATION_EXPIRED,
        *  WITHDRAW_ERROR_DENOMINATION_VALIDITY_IN_FUTURE,
        *  WITHDRAW_ERROR_AGE_RESTRICTION_NOT_SUPPORTED_BY_DENOMINATION,
+       *  WITHDRAW_ERROR_AGE_MASK_MISMATCH,
        * we use this one field.
        */
       const struct TALER_DenominationHashP *denom_h;
@@ -952,6 +954,7 @@ phase_check_keys (
 {
   struct TEH_KeyStateHandle *ksh;
   bool is_cs_denom[wc->request.withdraw.num_coins];
+  struct TALER_AgeMask age_mask = { 0 };
 
   memset (is_cs_denom,
           0,
@@ -986,6 +989,23 @@ phase_check_keys (
                              &wc->request.denoms_h[i],
                              &dk))
       return;
+    /* All coins of an age-restricted withdraw must use the same age
+       groups, as /reveal-withdraw derives their age commitments with
+       one mask. */
+    if (wc->request.withdraw.age_proof_required)
+    {
+      if (0 == i)
+        age_mask = dk->meta.age_mask;
+      if (age_mask.bits != dk->meta.age_mask.bits)
+      {
+        GNUNET_break_op (0);
+        SET_ERROR_WITH_DETAIL (wc,
+                               WITHDRAW_ERROR_AGE_MASK_MISMATCH,
+                               denom_h,
+                               &wc->request.denoms_h[i]);
+        return;
+      }
+    }
     switch (dk->denom_pub.bsign_pub_key->cipher)
     {
     case GNUNET_CRYPTO_BSA_INVALID:
@@ -1460,6 +1480,22 @@ phase_generate_reply_error (
                      msg));
       return;
     }
+  case WITHDRAW_ERROR_AGE_MASK_MISMATCH:
+    {
+      char msg[256];
+
+      GNUNET_snprintf (msg,
+                       sizeof(msg),
+                       "age mask of denomination %s differs from that of the first denomination",
+                       GNUNET_h2s (&wc->error.details.denom_h->hash));
+      finish_loop (wc,
+                   TALER_MHD_reply_with_error (
+                     wc->rc->connection,
+                     MHD_HTTP_BAD_REQUEST,
+                     TALER_EC_EXCHANGE_WITHDRAW_AGE_MASK_MISMATCH,
+                     msg));
+      return;
+    }
   case WITHDRAW_ERROR_MAXIMUM_AGE_TOO_LARGE:
     GNUNET_log (GNUNET_ERROR_TYPE_INFO,
                 "Generating JSON response with code %d\n",