[Reputation Oracle] feat: use timeSafeEqual for veriff

packages/apps/reputation-oracle/server/src/modules/kyc/kyc-webhook-auth.guard.ts

@@ -10,6 +10,7 @@ import {
 import { Request } from 'express';
 
 import { KycConfigService } from '@/config';
+import * as securityUtils from '@/utils/security';
 
 @Injectable()
 export class KycWebhookAuthGuard implements CanActivate {
@@ -18,7 +19,6 @@ export class KycWebhookAuthGuard implements CanActivate {
     const request: Request = context.switchToHttp().getRequest();
 
     const { headers, body } = request;
-    const apiKey = headers['x-auth-client'];
     const hmacSignature = headers['x-hmac-signature'];
 
     if (!hmacSignature) {
@@ -27,6 +27,12 @@ export class KycWebhookAuthGuard implements CanActivate {
         HttpStatus.BAD_REQUEST,
       );
     }
+    if (typeof hmacSignature !== 'string') {
+      throw new HttpException(
+        'Invalid HMAC Signature type',
+        HttpStatus.BAD_REQUEST,
+      );
+    }
 
     const signedPayload = createHmac(
       'sha256',
@@ -35,10 +41,7 @@ export class KycWebhookAuthGuard implements CanActivate {
       .update(JSON.stringify(body))
       .digest('hex');
 
-    if (
-      signedPayload !== hmacSignature ||
-      this.kycConfigService.apiKey !== apiKey
-    ) {
+    if (!securityUtils.safeCompare(signedPayload, hmacSignature)) {
       throw new HttpException(
         'HMAC Signature does not match',
         HttpStatus.UNAUTHORIZED,

packages/apps/reputation-oracle/server/src/utils/security.ts

@@ -1,3 +1,5 @@
+import crypto from 'crypto';
+
 import * as bcrypt from 'bcrypt';
 
 export function hashPassword(password: string): string {
@@ -12,3 +14,15 @@ export function comparePasswordWithHash(
 ): boolean {
   return bcrypt.compareSync(password, passwordHash);
 }
+
+export function safeCompare(a: string, b: string): boolean {
+  const bufA = Buffer.from(a);
+  const bufB = Buffer.from(b);
+
+  // Must be same length to avoid early return timing leaks
+  if (bufA.length !== bufB.length) {
+    return false;
+  }
+
+  return crypto.timingSafeEqual(bufA, bufB);
+}