From ca57fd4f0bee9ad2404796b7b428816a01b8af66 Mon Sep 17 00:00:00 2001
From: Andrew Jones <ajones@digitalbazaar.com>
Date: Thu, 17 Oct 2024 14:13:43 -0400
Subject: [PATCH] Create invalid disclosed VC w/ 2 components.

---
 tests/setup.js                    | 17 ++++++++++
 tests/suites/verify.js            |  3 +-
 tests/vc-generator/stubMethods.js | 55 +++++++++++++++++++++++++++++++
 3 files changed, 74 insertions(+), 1 deletion(-)

diff --git a/tests/setup.js b/tests/setup.js
index ff0d6aa..b1d149b 100644
--- a/tests/setup.js
+++ b/tests/setup.js
@@ -14,6 +14,10 @@ import {
   getMultikeys,
   issueCredentials
 } from './vc-generator/index.js';
+import {
+  encodeProofValue,
+  parseDisclosureProofValue
+} from './vc-generator/stubMethods.js';
 import {generators} from 'data-integrity-test-suite-assertion';
 import {writeFile} from 'node:fs/promises';
 
@@ -144,6 +148,19 @@ export async function verifySetup({credentials, keyTypes, suite}) {
     }
   }
   disclosed.invalid.valuePrefix = valuePrefix;
+  // invalid element count means less than 4 components
+  const componentCount = disclosed.invalid.componentCount = new Map();
+  for(const [keyType, versions] of disclosed?.basic) {
+    componentCount.set(keyType, new Map());
+    for(const [vcVersion, vc] of versions) {
+      const modifiedVc = structuredClone(vc);
+      const params = parseDisclosureProofValue({proof: modifiedVc.proof});
+      const payload = [params.bbsProof, params.presentationHeader];
+      modifiedVc.proof.proofValue = encodeProofValue({payload});
+      // perform test data mutation here
+      componentCount.get(keyType).set(vcVersion, modifiedVc);
+    }
+  }
   return {
     base,
     disclosed
diff --git a/tests/suites/verify.js b/tests/suites/verify.js
index 23b89be..b59262f 100644
--- a/tests/suites/verify.js
+++ b/tests/suites/verify.js
@@ -151,7 +151,8 @@ export function verifySuite({
         async function() {
           this.test.link = 'https://w3c.github.io/vc-di-bbs/#:~:text=If%20the%20result%20is%20not%20an%20array%20of%20five%2C%20six%2C%20or%20seven%20elements%20%E2%80%94%20a%20byte%20array%2C%20a%20map%20of%20integers%20to%20integers%2C%20two%20arrays%20of%20integers%2C%20and%20one%20or%20two%20byte%20arrays%3B%20an%20error%20MUST%20be%20raised%20and%20SHOULD%20convey%20an%20error%20type%20of%20PROOF_VERIFICATION_ERROR';
           await verificationFail({
-            credential: cloneTestVector(disclosed?.invalid?.elementCount),
+            credential: cloneTestVector(disclosed?.invalid?.componentCount),
+            verifier,
             reason: 'Should not verify a disclosed VC w/ less than 4 components'
           });
         });
diff --git a/tests/vc-generator/stubMethods.js b/tests/vc-generator/stubMethods.js
index 80665d9..6b2c359 100644
--- a/tests/vc-generator/stubMethods.js
+++ b/tests/vc-generator/stubMethods.js
@@ -439,3 +439,58 @@ async function _findProof({proofId, proofSet, dataIntegrityProof}) {
 export function stringToUtf8Bytes({str, utfOffset = 0}) {
   return TEXT_ENCODER.encode(str).map(b => b + utfOffset);
 }
+
+export function parseDisclosureProofValue({proof} = {}) {
+  try {
+    if(typeof proof?.proofValue !== 'string') {
+      throw new TypeError('"proof.proofValue" must be a string.');
+    }
+    if(proof.proofValue[0] !== 'u') {
+      throw new Error('Only base64url multibase encoding is supported.');
+    }
+
+    // decode from base64url
+    const proofValue = base64url.decode(proof.proofValue.slice(1));
+    if(!_startsWithBytes(proofValue, CBOR_PREFIX_DERIVED)) {
+      throw new TypeError('"proof.proofValue" must be a derived proof.');
+    }
+
+    const payload = proofValue.subarray(CBOR_PREFIX_DERIVED.length);
+    const [
+      bbsProof,
+      compressedLabelMap,
+      mandatoryIndexes,
+      selectiveIndexes,
+      presentationHeader
+    ] = cborg.decode(payload, {useMaps: true, tags: TAGS});
+
+    const labelMap = _decompressLabelMap(compressedLabelMap);
+    const params = {
+      bbsProof, labelMap, mandatoryIndexes, selectiveIndexes,
+      presentationHeader
+    };
+    return params;
+  } catch(e) {
+    const err = new TypeError(
+      'The proof does not include a valid "proofValue" property.');
+    err.cause = e;
+    throw err;
+  }
+}
+
+function _decompressLabelMap(compressedLabelMap) {
+  const map = new Map();
+  for(const [k, v] of compressedLabelMap.entries()) {
+    map.set(`c14n${k}`, `b${v}`);
+  }
+  return map;
+}
+
+function _startsWithBytes(buffer, prefix) {
+  for(let i = 0; i < prefix.length; ++i) {
+    if(buffer[i] !== prefix[i]) {
+      return false;
+    }
+  }
+  return true;
+}