taler-typescript-core

commit 1fb7d167bcce30e59d782e16151d63190f4fcb51
parent 40273e71e65ec916c4a809191f4b56a130c462ce
Author: Florian Dold <dold@taler.net>
Date:   Wed, 22 Jul 2026 12:21:19 +0200

wallet: verify the master signature of exchange signing keys

The online signing keys were the only part of /keys stored without checking
the signature that the exchange master key made over them; denominations,
wire accounts and global fees were all validated.

Diffstat:
M
packages/taler-wallet-core/src/exchanges.ts
 | 
30
+++++++++++++++++++++++++++++-

1 file changed, 29 insertions(+), 1 deletion(-)
diff --git a/packages/taler-wallet-core/src/exchanges.ts b/packages/taler-wallet-core/src/exchanges.ts
@@ -48,6 +48,7 @@ import {
   ExchangeEntryState,
   ExchangeGlobalFees,
   ExchangeKeysResponse,
+  ExchangeSignKeyJson,
   ExchangeListItem,
   ExchangeTosStatus,
   ExchangeUpdateStatus,
@@ -672,6 +673,32 @@ async function validateWireInfo(
  *
  * Throw an exception if they are invalid.
  */
+/**
+ * Check the master signature of every online signing key of the exchange.
+ */
+async function validateSignKeys(
+  wex: WalletExecutionContext,
+  signKeys: ExchangeSignKeyJson[],
+  masterPub: string,
+): Promise<void> {
+  for (const sk of signKeys) {
+    logger.trace("validating exchange signing key");
+    let isValid = false;
+    if (wex.ws.config.testing.insecureTrustExchange) {
+      isValid = true;
+    } else {
+      const { valid: v } = await wex.cryptoApi.isValidSignKey({
+        masterPub,
+        sk,
+      });
+      isValid = v;
+    }
+    if (!isValid) {
+      throw Error("exchange signing key signature invalid: " + sk.key);
+    }
+  }
+}
+
 async function validateGlobalFees(
   wex: WalletExecutionContext,
   fees: GlobalFees[],
@@ -1828,6 +1855,8 @@ export async function updateExchangeFromUrlHandler(
     keysInfo.master_public_key,
   );
 
+  await validateSignKeys(wex, keysInfo.signkeys, keysInfo.master_public_key);
+
   logger.trace("finished validating exchange /wire info");
 
   const tosMeta = await downloadTosMeta(wex, exchangeBaseUrl);
@@ -2031,7 +2060,6 @@ export async function updateExchangeFromUrlHandler(
     const drRowId = await tx.upsertExchangeDetails(newDetails);
 
     for (const sk of keysInfo.signkeys) {
-      // FIXME: validate signing keys before inserting them
       await tx.upsertExchangeSignKey({
         exchangeDetailsRowId: drRowId,
         masterSig: sk.master_sig,