From a1c534ec0ccc31510c916b0c8c9835f915528b7e Mon Sep 17 00:00:00 2001
From: Scott Nonnenberg <scott@signal.org>
Date: Wed, 7 Apr 2021 14:27:40 -0700
Subject: [PATCH] Fix CDS fetches; use proper hashing mechanism

---
 ts/Crypto.ts                                |  7 ++++---
 ts/test-both/util/synchronousCrypto_test.ts | 13 +++++++++++--
 ts/util/synchronousCrypto.ts                |  9 +++++++--
 3 files changed, 22 insertions(+), 7 deletions(-)

diff --git a/ts/Crypto.ts b/ts/Crypto.ts
index e47daf53c2..45428a5d7b 100644
--- a/ts/Crypto.ts
+++ b/ts/Crypto.ts
@@ -8,6 +8,7 @@ import {
   CipherType,
   encrypt,
   decrypt,
+  HashType,
   hash,
   sign,
 } from './util/synchronousCrypto';
@@ -470,8 +471,8 @@ export async function decryptAesGcm(
 
 // Hashing
 
-export async function sha256(data: ArrayBuffer): Promise<ArrayBuffer> {
-  return hash(data);
+export function sha256(data: ArrayBuffer): ArrayBuffer {
+  return hash(HashType.size256, data);
 }
 
 // Utility
@@ -628,7 +629,7 @@ export async function encryptCdsDiscoveryRequest(
   });
   const queryDataPlaintext = concatenateBytes(nonce, numbersArray.buffer);
   const queryDataKey = getRandomBytes(32);
-  const commitment = await sha256(queryDataPlaintext);
+  const commitment = sha256(queryDataPlaintext);
   const iv = getRandomBytes(12);
   const queryDataCiphertext = await encryptAesGcm(
     queryDataKey,
diff --git a/ts/test-both/util/synchronousCrypto_test.ts b/ts/test-both/util/synchronousCrypto_test.ts
index 8ad7dae752..dbb50da2d5 100644
--- a/ts/test-both/util/synchronousCrypto_test.ts
+++ b/ts/test-both/util/synchronousCrypto_test.ts
@@ -5,12 +5,21 @@ import { assert } from 'chai';
 import crypto from 'crypto';
 
 import { typedArrayToArrayBuffer as toArrayBuffer } from '../../Crypto';
-import { hash, sign, encrypt, decrypt } from '../../util/synchronousCrypto';
+import {
+  HashType,
+  hash,
+  sign,
+  encrypt,
+  decrypt,
+} from '../../util/synchronousCrypto';
 
 describe('synchronousCrypto', () => {
   describe('hash', () => {
     it('returns SHA512 hash of the input', () => {
-      const result = hash(toArrayBuffer(Buffer.from('signal')));
+      const result = hash(
+        HashType.size512,
+        toArrayBuffer(Buffer.from('signal'))
+      );
       assert.strictEqual(
         Buffer.from(result).toString('base64'),
         'WxneQjrfSlY95Bi+SAzDAr2cf3mxUXePeNYn6DILN4a8NFr9VelTbP5tGHdthi+' +
diff --git a/ts/util/synchronousCrypto.ts b/ts/util/synchronousCrypto.ts
index 1fcc1e8b6e..be17bb5b18 100644
--- a/ts/util/synchronousCrypto.ts
+++ b/ts/util/synchronousCrypto.ts
@@ -14,9 +14,14 @@ export function sign(key: ArrayBuffer, data: ArrayBuffer): ArrayBuffer {
   );
 }
 
-export function hash(data: ArrayBuffer): ArrayBuffer {
+export enum HashType {
+  size256 = 'sha256',
+  size512 = 'sha512',
+}
+
+export function hash(type: HashType, data: ArrayBuffer): ArrayBuffer {
   return toArrayBuffer(
-    crypto.createHash('sha512').update(Buffer.from(data)).digest()
+    crypto.createHash(type).update(Buffer.from(data)).digest()
   );
 }