62 lines
1.5 KiB
JavaScript
62 lines
1.5 KiB
JavaScript
import { random2048, generate_prime } from "./random_primes.js";
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import { mod_exp } from "./math.js";
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let p, q, pubKey, privKey;
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class PubKey {
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constructor(p, q) {
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this.n = p * q;
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// this.g = this.n + 1n;
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}
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encrypt(m) {
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// Compute g^m r^n mod n^2
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let r = random2048();
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// Resample to avoid modulo bias.
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while (r >= this.n) {
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r = random2048();
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}
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// Compute g^m by binomial theorem.
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let gm = (1n + this.n * m) % this.n ** 2n;
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// Compute g^m r^n from crt
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return (gm * mod_exp(r, this.n, this.n ** 2n)) % this.n ** 2n;
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}
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}
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class PrivKey {
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constructor(p, q) {
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this.n = p * q;
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this.lambda = (p - 1n) * (q - 1n);
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this.mu = mod_exp(this.lambda, this.lambda - 1n, this.n);
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}
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decrypt(c) {
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return (
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(((mod_exp(c, this.lambda, this.n ** 2n) - 1n) / this.n) * this.mu) % this.n
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);
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}
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}
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export function generate_keypair() {
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if (window.sessionStorage.getItem("p") === null) {
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p = generate_prime();
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window.sessionStorage.setItem("p", p);
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} else {
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p = BigInt(window.sessionStorage.getItem("p"));
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}
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if (window.sessionStorage.getItem("q") === null) {
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q = generate_prime();
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window.sessionStorage.setItem("q", q);
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} else {
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q = BigInt(window.sessionStorage.getItem("q"));
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}
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pubKey = new PubKey(p, q);
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privKey = new PrivKey(p, q);
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return { pubKey, privKey };
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}
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