/* - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - */
/* Block TEA (xxtea) Tiny Encryption Algorithm (c) Chris Veness 2002-2017 */
/* MIT Licence */
/* www.movable-type.co.uk/scripts/tea-block.html */
/* - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - */
'use strict';
/**
* Tiny Encryption Algorithm. David Wheeler & Roger Needham, Cambridge University Computer Lab.
*
* www.movable-type.co.uk/scripts/tea.pdf - TEA, a Tiny Encryption Algorithm (1994)
* www.movable-type.co.uk/scripts/xtea.pdf - Tea extensions (1997)
* www.movable-type.co.uk/scripts/xxtea.pdf - Correction to xtea (1998)
*/
class Tea {
/**
* Encrypts text using Corrected Block TEA (xxtea) algorithm.
*
* @param {string} plaintext - String to be encrypted (multi-byte safe).
* @param {string} password - Password to be used for encryption (1st 16 chars).
* @returns {string} Encrypted text (encoded as base64).
*/
static encrypt(plaintext, password) {
plaintext = String(plaintext);
password = String(password);
if (plaintext.length == 0) return(''); // nothing to encrypt
// v is n-word data vector; converted to array of longs from UTF-8 string
const v = Tea.strToLongs(Tea.utf8Encode(plaintext));
// k is 4-word key; simply convert first 16 chars of password as key
const k = Tea.strToLongs(Tea.utf8Encode(password).slice(0, 16));
const cipher = Tea.encode(v, k);
// convert array of longs to string
const ciphertext = Tea.longsToStr(cipher);
// convert binary string to base64 ascii for safe transport
const cipherbase64 = Tea.base64Encode(ciphertext);
return cipherbase64;
}
/**
* Decrypts text using Corrected Block TEA (xxtea) algorithm.
*
* @param {string} ciphertext - String to be decrypted.
* @param {string} password - Password to be used for decryption (1st 16 chars).
* @returns {string} Decrypted text.
* @throws {Error} Invalid ciphertext
*/
static decrypt(ciphertext, password) {
ciphertext = String(ciphertext);
password = String(password);
if (ciphertext.length == 0) return(''); // nothing to decrypt
// v is n-word data vector; converted to array of longs from base64 string
const v = Tea.strToLongs(Tea.base64Decode(ciphertext));
// k is 4-word key; simply convert first 16 chars of password as key
const k = Tea.strToLongs(Tea.utf8Encode(password).slice(0,16));
const plain = Tea.decode(v, k);
const plaintext = Tea.longsToStr(plain);
// strip trailing null chars resulting from filling 4-char blocks:
const plainUnicode = Tea.utf8Decode(plaintext.replace(/\0+$/,''));
return plainUnicode;
}
/**
* XXTEA: encodes array of unsigned 32-bit integers using 128-bit key.
*
* @param {number[]} v - Data vector.
* @param {number[]} k - Key.
* @returns {number[]} Encoded vector.
*/
static encode(v, k) {
if (v.length < 2) v[1] = 0; // algorithm doesn't work for n<2 so fudge by adding a null
const n = v.length;
const delta = 0x9e3779b9;
let q = Math.floor(6 + 52/n);
let z = v[n-1], y = v[0];
let mx, e, sum = 0;
while (q-- > 0) { // 6 + 52/n operations gives between 6 & 32 mixes on each word
sum += delta;
e = sum>>>2 & 3;
for (let p = 0; p < n; p++) {
y = v[(p+1)%n];
mx = (z>>>5 ^ y<<2) + (y>>>3 ^ z<<4) ^ (sum^y) + (k[p&3 ^ e] ^ z);
z = v[p] += mx;
}
}
return v;
}
/**
* XXTEA: decodes array of unsigned 32-bit integers using 128-bit key.
*
* @param {number[]} v - Data vector.
* @param {number[]} k - Key.
* @returns {number[]} Decoded vector.
*/
static decode(v, k) {
const n = v.length;
const delta = 0x9e3779b9;
const q = Math.floor(6 + 52/n);
let z = v[n-1], y = v[0];
let mx, e, sum = q*delta;
while (sum != 0) {
e = sum>>>2 & 3;
for (let p = n-1; p >= 0; p--) {
z = v[p>0 ? p-1 : n-1];
mx = (z>>>5 ^ y<<2) + (y>>>3 ^ z<<4) ^ (sum^y) + (k[p&3 ^ e] ^ z);
y = v[p] -= mx;
}
sum -= delta;
}
return v;
}
/**
* Converts string to array of longs (each containing 4 chars).
* @private
*/
static strToLongs(s) {
// note chars must be within ISO-8859-1 (Unicode code-point <= U+00FF) to fit 4/long
const l = new Array(Math.ceil(s.length/4));
for (let i=0; i<l.length; i++) {
// note little-endian encoding - endianness is irrelevant as long as it matches longsToStr()
l[i] = s.charCodeAt(i*4) + (s.charCodeAt(i*4+1)<<8) +
(s.charCodeAt(i*4+2)<<16) + (s.charCodeAt(i*4+3)<<24);
} // note running off the end of the string generates nulls since bitwise operators treat NaN as 0
return l;
}
/**
* Converts array of longs to string.
* @private
*/
static longsToStr(l) {
let str = '';
for (let i=0; i<l.length; i++) {
str += String.fromCharCode(l[i] & 0xff, l[i]>>>8 & 0xff, l[i]>>>16 & 0xff, l[i]>>>24 & 0xff);
}
return str;
}
/* - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - */
/**
* Encodes multi-byte string to utf8 - monsur.hossa.in/2012/07/20/utf-8-in-javascript.html
*/
static utf8Encode(str) {
return unescape(encodeURIComponent(str));
}
/**
* Decodes utf8 string to multi-byte
*/
static utf8Decode(utf8Str) {
try {
return decodeURIComponent(escape(utf8Str));
} catch (e) {
return utf8Str; // invalid UTF-8? return as-is
}
}
/**
* Encodes base64 - developer.mozilla.org/en-US/docs/Web/API/window.btoa, nodejs.org/api/buffer.html
*/
static base64Encode(str) {
if (typeof btoa != 'undefined') return btoa(str); // browser
if (typeof Buffer != 'undefined') return new Buffer(str, 'binary').toString('base64'); // Node.js
throw new Error('No Base64 Encode');
}
/**
* Decodes base64
*/
static base64Decode(b64Str) {
if (typeof atob == 'undefined' && typeof Buffer == 'undefined') throw new Error('No base64 decode');
try {
if (typeof atob != 'undefined') return atob(b64Str); // browser
if (typeof Buffer != 'undefined') return new Buffer(b64Str, 'base64').toString('binary'); // Node.js
} catch (e) {
throw new Error('Invalid ciphertext');
}
}
}
/* - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - */
if (typeof module != 'undefined' && module.exports) module.exports = Tea; // ≡ export default Tea