arc4
Version:
rc4 stream cipher
305 lines (274 loc) • 7.46 kB
JavaScript
'use strict';
/**
* @file rc4a normal
* @module arc4
* @subpackage normal
* @version 3.0.0
* @author hex7c0 <hex7c0@gmail.com>
* @copyright hex7c0 2014
* @license GPLv3
*/
/*
* initialize module
*/
var deprecate = require('util').deprecate;
// load
var box = [ 0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18,
19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30, 31, 32, 33, 34, 35, 36, 37,
38, 39, 40, 41, 42, 43, 44, 45, 46, 47, 48, 49, 50, 51, 52, 53, 54, 55, 56,
57, 58, 59, 60, 61, 62, 63, 64, 65, 66, 67, 68, 69, 70, 71, 72, 73, 74, 75,
76, 77, 78, 79, 80, 81, 82, 83, 84, 85, 86, 87, 88, 89, 90, 91, 92, 93, 94,
95, 96, 97, 98, 99, 100, 101, 102, 103, 104, 105, 106, 107, 108, 109, 110,
111, 112, 113, 114, 115, 116, 117, 118, 119, 120, 121, 122, 123, 124, 125,
126, 127, 128, 129, 130, 131, 132, 133, 134, 135, 136, 137, 138, 139, 140,
141, 142, 143, 144, 145, 146, 147, 148, 149, 150, 151, 152, 153, 154, 155,
156, 157, 158, 159, 160, 161, 162, 163, 164, 165, 166, 167, 168, 169, 170,
171, 172, 173, 174, 175, 176, 177, 178, 179, 180, 181, 182, 183, 184, 185,
186, 187, 188, 189, 190, 191, 192, 193, 194, 195, 196, 197, 198, 199, 200,
201, 202, 203, 204, 205, 206, 207, 208, 209, 210, 211, 212, 213, 214, 215,
216, 217, 218, 219, 220, 221, 222, 223, 224, 225, 226, 227, 228, 229, 230,
231, 232, 233, 234, 235, 236, 237, 238, 239, 240, 241, 242, 243, 244, 245,
246, 247, 248, 249, 250, 251, 252, 253, 254, 255 ];
/*
* functions
*/
/**
* Generate KSA.
*
* @function gKsa
* @param {Array} key - user key
* @return {Array}
*/
function gKsa(key) {
var j = 0;
var s = box.slice();
var len = key.length;
for (var i = 0; i < 256; ++i) {
j = (j + s[i] + key[i % len]) % 256;
s[j] = [ s[i], s[i] = s[j] ][0];
}
return s;
}
/**
* Generate PRGA.
*
* @function gPrga
* @param {Array} key - user key
* @param {Array} s - s1 vector
* @return {Array}
*/
function gPrga(key, s) {
var keystream = [];
var k = 0;
var j = 0;
var len = key.length;
for (var i = 0; i < len; ++i) {
k = (k + 1) % 256;
j = (j + s[k]) % 256;
s[j] = [ s[k], s[k] = s[j] ][0];
keystream[i] = s[(s[k] + s[j]) % 256];
}
return keystream;
}
/**
* Body cipher.
*
* @function body
* @param {Array|Buffer} inp - input
* @param {Array} ksa - ksa box
* @param {Array} prga - prga box
* @param {Array|Buffer} container - out container
* @param {Integer} length - limit
* @return {Array|Buffer}
*/
function body(inp, ksa, prga, container, length) {
var i = 0, j1 = 0, j2 = 0;
var out = container;
var s1 = ksa.slice();
var s2 = prga.slice();
for (var y = 0; y < length; ++y) {
i = (i + 1) % 256;
j1 = (j1 + s1[i]) % 256;
s1[j1] = [ s1[i], s1[i] = s1[j1] ][0];
out[y] = inp[y] ^ s2[(s1[i] + s1[j1]) % 256];
if (++y < length) {
j2 = (j2 + s2[i]) % 256;
s2[j2] = [ s2[i], s2[i] = s2[j2] ][0];
out[y] = inp[y] ^ s1[(s2[i] + s2[j1]) % 256];
}
}
return out;
}
/**
* export class
*
* @exports normal
* @function normal
* @param {String|Array|Buffer} password - user key
* @return {Rc4a}
*/
module.exports = function(password) {
return new Rc4a(password);
};
/*
* class
*/
/**
* Rc4a class
*
* @class Rc4a
* @param {String|Array|Buffer} key - user key
*/
function Rc4a(key) {
this.key = null;
this.derivatedKey = null;
this.ksa = null;
this.prga = null;
this.change(key);
}
/**
* change user key
*
* @function change
* @param {String|Array|Buffer} key - user key
*/
Rc4a.prototype.change = function(key) {
this.key = new Array(key.length);
if (Array.isArray(key)) {
this.key = key;
} else if (typeof (key) === 'string' || Buffer.isBuffer(key)) {
var keys = new Buffer(key);
for (var i = 0, ii = keys.length; i < ii; ++i) {
this.key[i] = keys[i];
}
} else {
throw new Error('Invalid data');
}
this.ksa = gKsa(this.key);
this.derivatedKey = gPrga(this.key, this.ksa);
this.prga = gKsa(this.derivatedKey);
return;
};
/**
* Rc4a string code
*
* @deprecated
* @function codeString
* @param {String} str - data
* @return {String}
*/
Rc4a.prototype.codeString = deprecate(function(str) {
var i = 0, j1 = 0, j2 = 0;
var out = '';
var s1 = this.ksa.slice();
var s2 = this.prga.slice();
for (var y = 0, l = str.length; y < l; ++y) {
i = (i + 1) % 256;
j1 = (j1 + s1[i]) % 256;
s1[j1] = [ s1[i], s1[i] = s1[j1] ][0];
out += String.fromCharCode(str.charCodeAt(y) ^ s2[(s1[i] + s1[j1]) % 256]);
if (++y < l) {
j2 = (j2 + s2[i]) % 256;
s2[j2] = [ s2[i], s2[i] = s2[j2] ][0];
out += String
.fromCharCode(str.charCodeAt(y) ^ s1[(s2[i] + s2[j2]) % 256]);
}
}
return out;
}, '"codeString" method is deprecated');
/**
* Rc4a string encode
*
* @function encodeString
* @param {String} str - data
* @param {String} [input_encoding] - input
* @param {String} [output_encoding] - output
* @return {String}
*/
Rc4a.prototype.encodeString = function(str, input_encoding, output_encoding) {
var out = new Buffer(str, input_encoding || 'utf8');
var l = out.length;
return new Buffer(body(out, this.ksa, this.prga, new Buffer(l), l))
.toString(output_encoding || 'hex');
};
/**
* Rc4a string decode
*
* @function decodeString
* @param {String} str - data
* @param {String} [input_encoding] - input
* @param {String} [output_encoding] - output
* @return {String}
*/
Rc4a.prototype.decodeString = function(str, input_encoding, output_encoding) {
var out = new Buffer(str, input_encoding || 'hex');
var l = out.length;
return new Buffer(body(out, this.ksa, this.prga, new Buffer(l), l))
.toString(output_encoding || 'utf8');
};
/**
* Rc4a array code
*
* @function codeArray
* @function encodeArray
* @function decodeArray
* @param {Array} arr - data
* @return {Array}
*/
Rc4a.prototype.encodeArray = Rc4a.prototype.decodeArray = function(arr) {
var l = arr.length;
return body(arr, this.ksa, this.prga, new Array(l), l);
};
/**
* Rc4a buffer code
*
* @function codeBuffer
* @function encodeBuffer
* @function decodeBuffer
* @param {Buffer} buff - data
* @return {Buffer}
*/
Rc4a.prototype.encodeBuffer = Rc4a.prototype.decodeBuffer = function(buff) {
var l = buff.length;
return body(buff, this.ksa, this.prga, new Buffer(l), l);
};
/**
* Rc4a mixed encode
*
* @function encode
* @param {String|Array|Buffer} boh - data
* @param {String} [input_encoding] - input
* @param {String} [output_encoding] - output
*/
Rc4a.prototype.encode = function(boh, input_encoding, output_encoding) {
if (typeof (boh) === 'string') {
return this.encodeString(boh, input_encoding, output_encoding);
}
if (Array.isArray(boh)) {
return this.encodeArray(boh);
}
if (Buffer.isBuffer(boh)) {
return this.encodeBuffer(boh);
}
throw new Error('Invalid data');
};
/**
* Rc4a mixed decode
*
* @function decode
* @param {String|Array|Buffer} boh - data
* @param {String} [input_encoding] - input
* @param {String} [output_encoding] - output
*/
Rc4a.prototype.decode = function(boh, input_encoding, output_encoding) {
if (typeof (boh) === 'string') {
return this.decodeString(boh, input_encoding, output_encoding);
}
if (Array.isArray(boh)) {
return this.decodeArray(boh);
}
if (Buffer.isBuffer(boh)) {
return this.decodeBuffer(boh);
}
throw new Error('Invalid data');
};