feat: Verify leaf signature (#2208)

* Update WA_CERT_DETAILS with issuer and public key

* certificate validation

* fix:lint

* padding

* lint: fix tab

---------

Co-authored-by: skidy89 <tutorialesyg310@gmail.com>

src/Defaults/index.ts

@@ -29,9 +29,10 @@ export const NOISE_WA_HEADER = Buffer.from([87, 65, 6, DICT_VERSION]) // last is
 /** from: https://stackoverflow.com/questions/3809401/what-is-a-good-regular-expression-to-match-a-url */
 export const URL_REGEX = /https:\/\/(?![^:@\/\s]+:[^:@\/\s]+@)[a-zA-Z0-9.-]+\.[a-zA-Z]{2,}(:\d+)?(\/[^\s]*)?/g
 
-// TODO: Add WA root CA
 export const WA_CERT_DETAILS = {
-	SERIAL: 0
+	SERIAL: 0,
+	ISSUER: 'WhatsAppLongTerm1',
+	PUBLIC_KEY: Buffer.from('142375574d0a587166aae71ebe516437c4a28b73e3695c6ce1f7f9545da8ee6b', 'hex')
 }
 
 export const PROCESSABLE_HISTORY_TYPES = [

src/Utils/noise-handler.ts

@@ -112,9 +112,35 @@ export const makeNoiseHandler = ({
 
 			const certDecoded = decrypt(serverHello!.payload!)
 
-			const { intermediate: certIntermediate /*leaf*/ } = proto.CertChain.decode(certDecoded)
-			// TODO: handle this leaf stuff
-			const { issuerSerial } = proto.CertChain.NoiseCertificate.Details.decode(certIntermediate!.details!)
+			const { intermediate: certIntermediate, leaf } = proto.CertChain.decode(certDecoded)
+			// leaf
+			if (!leaf?.details || !leaf?.signature) {
+				throw new Boom('invalid noise leaf certificate', { statusCode: 400 })
+			}
+
+			if (!certIntermediate?.details || !certIntermediate?.signature) {
+				throw new Boom('invalid noise intermediate certificate', { statusCode: 400 })
+			}
+
+			const details = proto.CertChain.NoiseCertificate.Details.decode(certIntermediate.details)
+
+			const { issuerSerial } = details
+
+			const verify = Curve.verify(details.key!, leaf.details, leaf.signature)
+
+			const verifyIntermediate = Curve.verify(
+				WA_CERT_DETAILS.PUBLIC_KEY,
+				certIntermediate.details,
+				certIntermediate.signature
+			)
+
+			if (!verify) {
+				throw new Boom('noise certificate signature invalid', { statusCode: 400 })
+			}
+
+			if (!verifyIntermediate) {
+				throw new Boom('noise intermediate certificate signature invalid', { statusCode: 400 })
+			}
 
 			if (issuerSerial !== WA_CERT_DETAILS.SERIAL) {
 				throw new Boom('certification match failed', { statusCode: 400 })