oicq/lib/algo/tea.js

QQ protocol!

"use strict";

const BUF7 = Buffer.alloc(7);
const table = [
    0x9e3779b9,
    0x3c6ef372,
    0xdaa66d2b,
    0x78dde6e4,
    0x1715609d,
    0xb54cda56,
    0x5384540f,
    0xf1bbcdc8,
    0x8ff34781,
    0x2e2ac13a,
    0xcc623af3,
    0x6a99b4ac,
    0x08d12e65,
    0xa708a81e,
    0x454021d7,
    0xe3779b90,
];

function _toUInt32(num) {
    return num >>> 0;
}

function _encrypt(x, y, k0, k1, k2, k3) {
    for (let i = 0; i < 16; ++i) {
        let aa = (_toUInt32((y << 4 >>> 0) + k0) ^ _toUInt32(y + table[i])) >>> 0 ^ _toUInt32(~~(y / 32) + k1);
        aa >>>= 0;
        x = _toUInt32(x + aa);
        let bb = (_toUInt32((x << 4 >>> 0) + k2) ^ _toUInt32(x + table[i])) >>> 0 ^ _toUInt32(~~(x / 32) + k3);
        bb >>>= 0;
        y = _toUInt32(y + bb);
    }
    return [x, y];
}

/**
 * qqtea encrypt
 * @param {Buffer} data 
 * @param {Buffer} key length = 16
 */
function encrypt(data, key) {
    let n = 6 - data.length >>> 0;
    n = n % 8 + 2;
    const v = Buffer.concat([
        Buffer.from([(n - 2) | 0xF8]),
        Buffer.allocUnsafe(n),
        data,
        BUF7
    ]);
    const k0 = key.readUInt32BE(0);
    const k1 = key.readUInt32BE(4);
    const k2 = key.readUInt32BE(8);
    const k3 = key.readUInt32BE(12);
    let r1 = 0, r2 = 0, t1 = 0, t2 = 0;
    for (let i = 0; i < v.length; i += 8) {
        const a1 = v.readUInt32BE(i);
        const a2 = v.readUInt32BE(i + 4);
        const b1 = a1 ^ r1;
        const b2 = a2 ^ r2;
        const [x, y] = _encrypt(b1 >>> 0, b2 >>> 0, k0, k1, k2, k3);
        r1 = x ^ t1;
        r2 = y ^ t2;
        t1 = b1;
        t2 = b2;
        v.writeInt32BE(r1, i);
        v.writeInt32BE(r2, i + 4);
    }
    return v;
}

function _decrypt(x, y, k0, k1, k2, k3) {
    for (let i = 15; i >= 0; --i) {
        let aa = (_toUInt32((x << 4 >>> 0) + k2) ^ _toUInt32(x + table[i])) >>> 0 ^ _toUInt32(~~(x / 32) + k3);
        y = y - aa >>> 0;
        let bb = (_toUInt32((y << 4 >>> 0) + k0) ^ _toUInt32(y + table[i])) >>> 0 ^ _toUInt32(~~(y / 32) + k1);
        x = x - bb >>> 0;
    }
    return [x, y];
}

/**
 * qqtea decrypt
 * @param {Buffer} encrypted 
 * @param {Buffer} key length = 16
 */
function decrypt(encrypted, key) {
    if (encrypted.length % 8) {
        throw new Error("length of encrypted data must be a multiple of 8");
    }
    const k0 = key.readUInt32BE(0);
    const k1 = key.readUInt32BE(4);
    const k2 = key.readUInt32BE(8);
    const k3 = key.readUInt32BE(12);
    let r1 = 0, r2 = 0, t1 = 0, t2 = 0, x = 0, y = 0;
    for (let i = 0; i < encrypted.length; i += 8) {
        const a1 = encrypted.readUInt32BE(i);
        const a2 = encrypted.readUInt32BE(i + 4);
        const b1 = a1 ^ x;
        const b2 = a2 ^ y;
        [x, y] = _decrypt(b1 >>> 0, b2 >>> 0, k0, k1, k2, k3);
        r1 = x ^ t1;
        r2 = y ^ t2;
        t1 = a1;
        t2 = a2;
        encrypted.writeInt32BE(r1, i);
        encrypted.writeInt32BE(r2, i + 4);
    }
    if (Buffer.compare(encrypted.slice(encrypted.length - 7), BUF7) !== 0)
        throw new Error("encrypted data is illegal");
    return encrypted.slice(
        (encrypted[0] & 0x07) + 3,
        encrypted.length - 7
    );
}

module.exports = {
    encrypt, decrypt
};