needs to be taken mod n for some reason.

static/js/paillier.js

@@ -8,35 +8,39 @@ class PubKey {
 
     encrypt(m) {
         // Compute g^m r^n mod n^2
-        let r = this.n;
+        let r = random2048();
 
-        while (r >= n) {
+        while (r >= this.n) {
             r = random2048();
         }
 
         // Compute g^m by binomial theorem.
-        let gm = 1n + this.n * m;
-        // Compute g^m r^n from fact that g^n = 1
-        return fastModularExponentiation(gm * r, this.n, this.n ** 2);
+        let gm = (1n + this.n * m) % this.n ** 2n;
+        // Compute g^m r^n from crt
+        return (gm * fastModularExponentiation(r, this.n, this.n ** 2n)) % this.n ** 2n;
     }
 }
 
 class PrivKey {
-    constructor(lambda, mu) {
-        this.lambda = lambda;
-        this.mu = mu;
+    constructor(p, q) {
+        this.n = p * q;
+        this.lambda = (p - 1n) * (q - 1n);
+        this.mu = fastModularExponentiation(this.lambda, this.lambda - 1n, this.n);
+    }
+
+    decrypt(c) {
+        return (
+            (((fastModularExponentiation(c, this.lambda, this.n ** 2n) - 1n) / this.n) *
+                (this.mu % this.n)) %
+            this.n
+        );
     }
 }
 
 document.addEventListener("DOMContentLoaded", () => {
-    return;
-
     p = generate_prime();
     q = generate_prime();
 
-    let n = p * q;
-    let lambda = (p - 1n) * (q - 1n);
-
     pubKey = new PubKey(p, q);
-    privKey = new PrivKey(lambda, fastModularExponentiation(lambda, lambda - 1n, n));
+    privKey = new PrivKey(p, q);
 });