Add ecdsa-sd-2023 serialize disclosure function into proxies.

Author: aljones15

tests/suites/proxies.js

@@ -2,8 +2,22 @@
  * Copyright 2024 Digital Bazaar, Inc.
  * SPDX-License-Identifier: BSD-3-Clause
  */
+import * as base64url from 'base64url-universal';
+import * as cborg from 'cborg';
 import crypto from 'node:crypto';
 
+/**
+ * Creates a proxy of an object with stubs.
+ *
+ * @see https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Proxy
+ *
+ * @param {object} options - Options to use.
+ * @param {object} options.original - The original object.
+ * @param {object} options.stubs - Stubs to replace the original objects
+ *   properties and methods.
+ *
+ * @returns {Proxy<object>} Returns a Proxy.
+ */
 export function createProxy({original, stubs}) {
   if(typeof original === 'object') {
     throw new Error(`Expected parameter original to be an object received ` +
@@ -111,17 +125,20 @@ export function invalidHashProxy({
   return suite;
 }
 
+// concat 2 unit8Arrays together
 function _concat(b1, b2) {
   const rval = new Uint8Array(b1.length + b2.length);
   rval.set(b1, 0);
   rval.set(b2, b1.length);
   return rval;
 }
 
+// sha hashing function
 export async function sha({algorithm, string}) {
   return new Uint8Array(crypto.createHash(algorithm).update(string).digest());
 }
 
+// ecdsa-rdfc-2019 _canonizeProof method
 async function _canonizeProof(proof, {
   document, cryptosuite, dataIntegrityProof, c14nOptions
 }) {
@@ -137,3 +154,44 @@ async function _canonizeProof(proof, {
   return cryptosuite.canonize(proof, c14nOptions);
 }
 
+// ecdsa-sd-2023 method that uses invalid cbor tags
+export function serializeDisclosureProofValue({
+  baseSignature, publicKey, signatures, labelMap, mandatoryIndexes
+} = {}) {
+  const CBOR_PREFIX_DERIVED = new Uint8Array([0xd9, 0x5d, 0x01]);
+  // encode as multibase (base64url no pad) CBOR
+  const payload = [
+    // Uint8Array
+    baseSignature,
+    // Uint8Array
+    publicKey,
+    // array of Uint8Arrays
+    signatures,
+    // Map of strings => strings compressed to ints => Uint8Arrays
+    _compressLabelMap(labelMap),
+    // array of numbers
+    mandatoryIndexes
+  ];
+  const cbor = _concatBuffers([
+    CBOR_PREFIX_DERIVED, cborg.encode(payload, {useMaps: true})
+  ]);
+  return `u${base64url.encode(cbor)}`;
+}
+
+function _concatBuffers(buffers) {
+  const bytes = new Uint8Array(buffers.reduce((acc, b) => acc + b.length, 0));
+  let offset = 0;
+  for(const b of buffers) {
+    bytes.set(b, offset);
+    offset += b.length;
+  }
+  return bytes;
+}
+
+function _compressLabelMap(labelMap) {
+  const map = new Map();
+  for(const [k, v] of labelMap.entries()) {
+    map.set(parseInt(k.slice(4), 10), base64url.decode(v.slice(1)));
+  }
+  return map;
+}