use same salt derivation as C code for forgettable fields

packages/taler-wallet-core/src/util/contractTerms.test.ts

@@ -95,3 +95,28 @@ test("contract terms canon hashing (nested)", (t) => {
   t.true(ContractTermsUtil.validateForgettable(c3));
   t.true(ContractTermsUtil.validateForgettable(c4));
 });
+
+test("contract terms reference vector", (t) => {
+  const j = {
+    k1: 1,
+    $forgettable: {
+      k1: "SALT",
+    },
+    k2: {
+      n1: true,
+      $forgettable: {
+        n1: "salt",
+      },
+    },
+    k3: {
+      n1: "string",
+    },
+  };
+
+  const h = ContractTermsUtil.hashContractTerms(j);
+
+  t.deepEqual(
+    h,
+    "VDE8JPX0AEEE3EX1K8E11RYEWSZQKGGZCV6BWTE4ST1C8711P7H850Z7F2Q2HSSYETX87ERC2JNHWB7GTDWTDWMM716VKPSRBXD7SRR",
+  );
+});

packages/taler-wallet-core/src/util/contractTerms.ts

@@ -65,7 +65,7 @@ export namespace ContractTermsUtil {
             const membValCanon = stringToBytes(
               canonicalJson(scrub(dup[x])) + "\0",
             );
-            const membSalt = decodeCrock(dup.$forgettable[x]);
+            const membSalt = stringToBytes(dup.$forgettable[x] + "\0");
             const h = kdf(64, membValCanon, membSalt, new Uint8Array([]));
             dup.$forgotten[x] = encodeCrock(h);
           }
@@ -230,6 +230,7 @@ export namespace ContractTermsUtil {
   export function hashContractTerms(contractTerms: unknown): string {
     const cleaned = scrub(contractTerms);
     const canon = canonicalJson(cleaned) + "\0";
+    console.warn(`canon '${canon}'`)
     return encodeCrock(hash(stringToBytes(canon)));
   }
 }