lightsword
Version:
LightSword Secure SOCKS5 Proxy / iOS VPN Server
111 lines (110 loc) • 3.59 kB
JavaScript
'use strict';
/* chacha20 - 256 bits */
// Written in 2014 by Devi Mandiri. Public domain.
//
// Implementation derived from chacha-ref.c version 20080118
// See for details: http://cr.yp.to/chacha/chacha-20080128.pdf
function U8TO32_LE(x, i) {
return x[i] | (x[i + 1] << 8) | (x[i + 2] << 16) | (x[i + 3] << 24);
}
function U32TO8_LE(x, i, u) {
x[i] = u;
u >>>= 8;
x[i + 1] = u;
u >>>= 8;
x[i + 2] = u;
u >>>= 8;
x[i + 3] = u;
}
function ROTATE(v, c) {
return (v << c) | (v >>> (32 - c));
}
class Chacha20 {
constructor(key, nonce, counter) {
this.input = new Uint32Array(16);
// https://tools.ietf.org/html/draft-irtf-cfrg-chacha20-poly1305-01#section-2.3
this.input[0] = 1634760805;
this.input[1] = 857760878;
this.input[2] = 2036477234;
this.input[3] = 1797285236;
this.input[4] = U8TO32_LE(key, 0);
this.input[5] = U8TO32_LE(key, 4);
this.input[6] = U8TO32_LE(key, 8);
this.input[7] = U8TO32_LE(key, 12);
this.input[8] = U8TO32_LE(key, 16);
this.input[9] = U8TO32_LE(key, 20);
this.input[10] = U8TO32_LE(key, 24);
this.input[11] = U8TO32_LE(key, 28);
// be compatible with the reference ChaCha depending on the nonce size
if (nonce.length == 12) {
this.input[12] = counter;
this.input[13] = U8TO32_LE(nonce, 0);
this.input[14] = U8TO32_LE(nonce, 4);
this.input[15] = U8TO32_LE(nonce, 8);
}
else {
this.input[12] = counter;
this.input[13] = 0;
this.input[14] = U8TO32_LE(nonce, 0);
this.input[15] = U8TO32_LE(nonce, 4);
}
}
update(raw) {
let cipherText = new Buffer(raw.length);
this.encrypt(cipherText, raw, raw.length);
return cipherText;
}
final() {
return new Buffer(0);
}
quarterRound(x, a, b, c, d) {
x[a] += x[b];
x[d] = ROTATE(x[d] ^ x[a], 16);
x[c] += x[d];
x[b] = ROTATE(x[b] ^ x[c], 12);
x[a] += x[b];
x[d] = ROTATE(x[d] ^ x[a], 8);
x[c] += x[d];
x[b] = ROTATE(x[b] ^ x[c], 7);
}
encrypt(dst, src, len) {
let x = new Uint32Array(16);
let output = new Uint8Array(64);
let i, dpos = 0, spos = 0;
while (len > 0) {
for (i = 16; i--;)
x[i] = this.input[i];
for (i = 20; i > 0; i -= 2) {
this.quarterRound(x, 0, 4, 8, 12);
this.quarterRound(x, 1, 5, 9, 13);
this.quarterRound(x, 2, 6, 10, 14);
this.quarterRound(x, 3, 7, 11, 15);
this.quarterRound(x, 0, 5, 10, 15);
this.quarterRound(x, 1, 6, 11, 12);
this.quarterRound(x, 2, 7, 8, 13);
this.quarterRound(x, 3, 4, 9, 14);
}
for (i = 16; i--;)
x[i] += this.input[i];
for (i = 16; i--;)
U32TO8_LE(output, 4 * i, x[i]);
this.input[12] += 1;
if (!this.input[12]) {
this.input[13] += 1;
}
if (len <= 64) {
for (i = len; i--;) {
dst[i + dpos] = src[i + spos] ^ output[i];
}
return;
}
for (i = 64; i--;) {
dst[i + dpos] = src[i + spos] ^ output[i];
}
len -= 64;
spos += 64;
dpos += 64;
}
}
}
exports.Chacha20 = Chacha20;