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-rw-r--r--src/mint-lib/mint_api_refresh.c141
-rw-r--r--src/mint/taler-mint-httpd_responses.c2
2 files changed, 140 insertions, 3 deletions
diff --git a/src/mint-lib/mint_api_refresh.c b/src/mint-lib/mint_api_refresh.c
index dad0ec16..ede95af5 100644
--- a/src/mint-lib/mint_api_refresh.c
+++ b/src/mint-lib/mint_api_refresh.c
@@ -25,6 +25,7 @@
#include <microhttpd.h> /* just for HTTP status codes */
#include <gnunet/gnunet_util_lib.h>
#include "taler_mint_service.h"
+#include "mint_api_common.h"
#include "mint_api_json.h"
#include "mint_api_context.h"
#include "mint_api_handle.h"
@@ -59,6 +60,11 @@ struct MeltedCoinP
struct TALER_AmountNBO fee_melt;
/**
+ * The original value of the coin.
+ */
+ struct TALER_AmountNBO original_value;
+
+ /**
* Transfer private keys for each cut-and-choose dimension.
*/
struct TALER_TransferPrivateKeyP transfer_priv[TALER_CNC_KAPPA];
@@ -170,6 +176,11 @@ struct MeltedCoin
struct TALER_Amount fee_melt;
/**
+ * The original value of the coin.
+ */
+ struct TALER_Amount original_value;
+
+ /**
* Transfer private keys for each cut-and-choose dimension.
*/
struct TALER_TransferPrivateKeyP transfer_priv[TALER_CNC_KAPPA];
@@ -381,9 +392,10 @@ serialize_melted_coin (const struct MeltedCoin *mc,
mcp.coin_priv = mc->coin_priv;
TALER_amount_hton (&mcp.melt_amount_with_fee,
&mc->melt_amount_with_fee);
-
TALER_amount_hton (&mcp.fee_melt,
&mc->fee_melt);
+ TALER_amount_hton (&mcp.original_value,
+ &mc->original_value);
for (i=0;i<TALER_CNC_KAPPA;i++)
mcp.transfer_priv[i] = mc->transfer_priv[i];
mcp.deposit_valid_until = GNUNET_TIME_absolute_hton (mc->deposit_valid_until);
@@ -464,6 +476,8 @@ deserialize_melted_coin (struct MeltedCoin *mc,
&mcp.melt_amount_with_fee);
TALER_amount_ntoh (&mc->fee_melt,
&mcp.fee_melt);
+ TALER_amount_ntoh (&mc->original_value,
+ &mcp.original_value);
for (i=0;i<TALER_CNC_KAPPA;i++)
mc->transfer_priv[i] = mcp.transfer_priv[i];
mc->deposit_valid_until = GNUNET_TIME_absolute_ntoh (mcp.deposit_valid_until);
@@ -868,6 +882,7 @@ TALER_MINT_refresh_prepare (unsigned int num_melts,
md.melted_coins[i].coin_priv = melt_privs[i];
md.melted_coins[i].melt_amount_with_fee = melt_amounts[i];
md.melted_coins[i].fee_melt = melt_pks[i].fee_refresh;
+ md.melted_coins[i].original_value = melt_pks[i].value;
for (j=0;j<TALER_CNC_KAPPA;j++)
{
struct GNUNET_CRYPTO_EcdhePrivateKey *tpk;
@@ -1091,6 +1106,122 @@ verify_refresh_melt_signature_ok (struct TALER_MINT_RefreshMeltHandle *rmh,
/**
+ * Verify that the signatures on the "403 FORBIDDEN" response from the
+ * mint demonstrating customer double-spending are valid.
+ *
+ * @param rmh melt handle
+ * @param json json reply with the signature(s) and transaction history
+ * @return #GNUNET_OK if the signature(s) is valid, #GNUNET_SYSERR if not
+ */
+static int
+verify_refresh_melt_signature_forbidden (struct TALER_MINT_RefreshMeltHandle *rmh,
+ json_t *json)
+{
+ json_t *history;
+ struct TALER_Amount original_value;
+ struct TALER_Amount melt_value_with_fee;
+ struct TALER_Amount total;
+ struct TALER_CoinSpendPublicKeyP coin_pub;
+ unsigned int i;
+ struct MAJ_Specification spec[] = {
+ // MAJ_spec_json ("history", &history), // FIXME!
+ MAJ_spec_fixed_auto ("coin_pub", &coin_pub),
+ MAJ_spec_amount ("original_value", &original_value),
+ MAJ_spec_amount ("requested_value", &melt_value_with_fee),
+ MAJ_spec_end
+ };
+ const struct MeltedCoin *mc;
+
+ /* parse JSON reply */
+ if (GNUNET_OK !=
+ MAJ_parse_json (json,
+ spec))
+ {
+ GNUNET_break_op (0);
+ return GNUNET_SYSERR;
+ }
+
+ /* Find out which coin was deemed problematic by the mint */
+ mc = NULL;
+ for (i=0;i<rmh->md->num_melted_coins;i++)
+ {
+ if (0 == TALER_amount_cmp (&melt_value_with_fee,
+ &rmh->md->melted_coins[i].melt_amount_with_fee))
+ {
+ struct TALER_CoinSpendPublicKeyP mc_pub;
+
+ GNUNET_CRYPTO_eddsa_key_get_public (&rmh->md->melted_coins[i].coin_priv.eddsa_priv,
+ &mc_pub.eddsa_pub);
+ if (0 == memcmp (&mc_pub,
+ &coin_pub,
+ sizeof (struct TALER_CoinSpendPublicKeyP)))
+ {
+ mc = &rmh->md->melted_coins[i];
+ break;
+ }
+ }
+ }
+ if (NULL == mc)
+ {
+ /* coin not found in our original request */
+ GNUNET_break_op (0);
+ return GNUNET_SYSERR;
+ }
+
+ /* check basic coin properties */
+ if (0 != TALER_amount_cmp (&original_value,
+ &mc->original_value))
+ {
+ /* We disagree on the value of the coin */
+ GNUNET_break_op (0);
+ return GNUNET_SYSERR;
+ }
+ if (0 != TALER_amount_cmp (&melt_value_with_fee,
+ &mc->melt_amount_with_fee))
+ {
+ /* We disagree on the value of the coin */
+ GNUNET_break_op (0);
+ return GNUNET_SYSERR;
+ }
+
+ /* verify coin history */
+ history = json_object_get (json,
+ "history");
+ if (GNUNET_OK !=
+ TALER_MINT_verify_coin_history_ (original_value.currency,
+ &coin_pub,
+ history,
+ &total))
+ {
+ GNUNET_break_op (0);
+ return GNUNET_SYSERR;
+ }
+
+ /* check if melt operation was really too expensive given history */
+ if (GNUNET_OK !=
+ TALER_amount_add (&total,
+ &total,
+ &melt_value_with_fee))
+ {
+ /* clearly not OK if our transaction would have caused
+ the overflow... */
+ return GNUNET_OK;
+ }
+
+ if (0 >= TALER_amount_cmp (&total,
+ &original_value))
+ {
+ /* transaction should have still fit */
+ GNUNET_break (0);
+ return GNUNET_SYSERR;
+ }
+
+ /* everything OK, valid proof of double-spending was provided */
+ return GNUNET_OK;
+}
+
+
+/**
* Function called when we're done processing the
* HTTP /refresh/melt request.
*
@@ -1138,7 +1269,13 @@ handle_refresh_melt_finished (void *cls,
break;
case MHD_HTTP_FORBIDDEN:
/* Double spending; check signatures on transaction history */
- GNUNET_break (0); // FIXME: NOT implemented!
+ if (GNUNET_OK !=
+ verify_refresh_melt_signature_forbidden (rmh,
+ json))
+ {
+ GNUNET_break_op (0);
+ response_code = 0;
+ }
break;
case MHD_HTTP_UNAUTHORIZED:
/* Nothing really to verify, mint says one of the signatures is
diff --git a/src/mint/taler-mint-httpd_responses.c b/src/mint/taler-mint-httpd_responses.c
index 48c0a748..0e2f9070 100644
--- a/src/mint/taler-mint-httpd_responses.c
+++ b/src/mint/taler-mint-httpd_responses.c
@@ -695,7 +695,7 @@ TMH_RESPONSE_reply_withdraw_sign_success (struct MHD_Connection *connection,
* @param coin_pub public key of the coin
* @param coin_value original value of the coin
* @param tl transaction history for the coin
- * @param requested how much this coin was supposed to contribute
+ * @param requested how much this coin was supposed to contribute, including fee
* @param residual remaining value of the coin (after subtracting @a tl)
* @return a MHD result code
*/
generated by cgit v1.2.3 (git 2.39.1) at 2025-10-31 13:36:00 +0000