code cleanup

src/Utils/lt-hash.ts

@@ -0,0 +1,57 @@
+import { hkdf } from './crypto'
+
+/**
+ * LT Hash is a summation based hash algorithm that maintains the integrity of a piece of data
+ * over a series of mutations. You can add/remove mutations and it'll return a hash equal to 
+ * if the same series of mutations was made sequentially.
+ */
+
+const o = 128;
+
+class d {
+
+	salt: string
+
+	constructor(e: string) {
+		this.salt = e
+	}
+	add(e, t) {
+		var r = this;
+		for(const item of t) {
+			e = r._addSingle(e, item)
+		}
+		return e
+	}
+	subtract(e, t) {
+		var r = this;
+		for(const item of t) {
+			e = r._subtractSingle(e, item)
+		}
+		return e
+	}
+	subtractThenAdd(e, t, r) {
+		var n = this;
+		return n.add(n.subtract(e, r), t)
+	}
+	_addSingle(e, t) {
+		var r = this;
+		const n = new Uint8Array(hkdf(Buffer.from(t), o, { info: r.salt })).buffer;
+		return r.performPointwiseWithOverflow(e, n, ((e,t)=>e + t))
+	}
+	_subtractSingle(e, t) {
+		var r = this;
+
+		const n = new Uint8Array(hkdf(Buffer.from(t), o, { info: r.salt })).buffer;
+		return r.performPointwiseWithOverflow(e, n, ((e,t)=>e - t))
+	}
+	performPointwiseWithOverflow(e, t, r) {
+		const n = new DataView(e)
+		  , i = new DataView(t)
+		  , a = new ArrayBuffer(n.byteLength)
+		  , s = new DataView(a);
+		for (let e = 0; e < n.byteLength; e += 2)
+			s.setUint16(e, r(n.getUint16(e, !0), i.getUint16(e, !0)), !0);
+		return a
+	}
+}
+export const LT_HASH_ANTI_TAMPERING = new d('WhatsApp Patch Integrity')