tplink-smarthome-crypto/lib/index.js

TP-Link Smarthome Crypto

"use strict";
/**
 * TP-Link Smarthome Crypto
 *
 * TCP communication includes a 4 byte header, UDP does not.
 * @packageDocumentation
 */
Object.defineProperty(exports, "__esModule", { value: true });
exports.decryptWithHeader = exports.decrypt = exports.encryptWithHeader = exports.encrypt = void 0;
/* eslint-disable @typescript-eslint/no-explicit-any */
/**
 * Encrypts input where each byte is XOR'd with the previous encrypted byte.
 *
 * @param input - Data to encrypt
 * @param firstKey - Value to XOR first byte of input
 * @returns encrypted buffer
 */
function encrypt(input, firstKey = 0xab) {
    const buf = Buffer.from(input);
    let key = firstKey;
    for (let i = 0; i < buf.length; i += 1) {
        // eslint-disable-next-line no-bitwise
        buf[i] ^= key;
        key = buf[i];
    }
    return buf;
}
exports.encrypt = encrypt;
/**
 * Encrypts input that has a 4 byte big-endian length header;
 * each byte is XOR'd with the previous encrypted byte.
 *
 * @param input - Data to encrypt
 * @param firstKey - Value to XOR first byte of input
 * @returns encrypted buffer with header
 */
function encryptWithHeader(input, firstKey = 0xab) {
    const msgBuf = encrypt(input, firstKey);
    const outBuf = Buffer.alloc(msgBuf.length + 4);
    outBuf.writeUInt32BE(msgBuf.length, 0);
    msgBuf.copy(outBuf, 4);
    return outBuf;
}
exports.encryptWithHeader = encryptWithHeader;
/**
 * Decrypts input where each byte is XOR'd with the previous encrypted byte.
 *
 * @param input - Encrypted Buffer
 * @param firstKey - Value to XOR first byte of input
 * @returns decrypted buffer
 */
function decrypt(input, firstKey = 0xab) {
    const buf = Buffer.from(input);
    let key = firstKey;
    for (let i = 0; i < buf.length; i += 1) {
        const nextKey = buf[i];
        // eslint-disable-next-line no-bitwise
        buf[i] ^= key;
        key = nextKey;
    }
    return buf;
}
exports.decrypt = decrypt;
/**
 * Decrypts input that has a 4 byte big-endian length header;
 * each byte is XOR'd with the previous encrypted byte
 *
 * @param input - Encrypted Buffer with header
 * @param firstKey - Value to XOR first byte of input
 * @returns decrypted buffer
 */
function decryptWithHeader(input, firstKey = 0xab) {
    if (input instanceof Buffer)
        return decrypt(input.subarray(4), firstKey);
    return decrypt(input.slice(4), firstKey);
}
exports.decryptWithHeader = decryptWithHeader;
//# sourceMappingURL=index.js.map