RC4 encryption in javascript and php

rc4.js

/*
 * RC4 symmetric cipher encryption/decryption
 *
 * @license Public Domain
 * @param string key - secret key for encryption/decryption
 * @param string str - string to be encrypted/decrypted
 * @return string
 */
function rc4(key, str) {
	var s = [], j = 0, x, res = '';
	for (var i = 0; i < 256; i++) {
		s[i] = i;
	}
	for (i = 0; i < 256; i++) {
		j = (j + s[i] + key.charCodeAt(i % key.length)) % 256;
		x = s[i];
		s[i] = s[j];
		s[j] = x;
	}
	i = 0;
	j = 0;
	for (var y = 0; y < str.length; y++) {
		i = (i + 1) % 256;
		j = (j + s[i]) % 256;
		x = s[i];
		s[i] = s[j];
		s[j] = x;
		res += String.fromCharCode(str.charCodeAt(y) ^ s[(s[i] + s[j]) % 256]);
	}
	return res;
}

rc4.php

<?php

/*
 * RC4 symmetric cipher encryption/decryption
 *
 * @license Public Domain
 * @param string key - secret key for encryption/decryption
 * @param string str - string to be encrypted/decrypted
 * @return string
 */
function rc4($key, $str) {
	$s = array();
	for ($i = 0; $i < 256; $i++) {
		$s[$i] = $i;
	}
	$j = 0;
	for ($i = 0; $i < 256; $i++) {
		$j = ($j + $s[$i] + ord($key[$i % strlen($key)])) % 256;
		$x = $s[$i];
		$s[$i] = $s[$j];
		$s[$j] = $x;
	}
	$i = 0;
	$j = 0;
	$res = '';
	for ($y = 0; $y < strlen($str); $y++) {
		$i = ($i + 1) % 256;
		$j = ($j + $s[$i]) % 256;
		$x = $s[$i];
		$s[$i] = $s[$j];
		$s[$j] = $x;
		$res .= $str[$y] ^ chr($s[($s[$i] + $s[$j]) % 256]);
	}
	return $res;
}

?>

Why is there no support for streaming? Or at least keeping the internal state?
Can you add that please?

RC4 is a stream cipher so there has to be support for transforming data while keeping the internal state of the encryption/decryption SBox (https://en.wikipedia.org/wiki/RC4 see: Key scheduling)

nevermind, this one does the trick
https://www.npmjs.com/package/simple-rc4
;-)

Here's my port to AutoIt3:

Func rc4($sKey, $sStr)
	Local $s[256], $j = 0, $x, $res, $y, $i
	Local $uBound
	For $i = 0 To 255
		$s[$i] = $i
	Next
	For $i = 0 To 255
		$j = Mod(($j + $s[$i] + Asc(StringMid($sKey, Mod($i, StringLen($sKey))+1, 1))), 256)
		$x = $s[$i]
		$s[$i] = $s[$j]
		$s[$j] = $x
	Next
	$i = 0
	$j = 0
	For $y = 0 To StringLen($sStr)-1
		$i = Mod(($i + 1), 256)
		$j = Mod(($j + $s[$i]), 256)
		$x = $s[$i]
		$s[$i] = $s[$j]
		$s[$j] = $x
		$res &= Chr(BitXOR(Asc(StringMid($sStr, $y+1, 1)), ($s[Mod(($s[$i] + $s[$j]), 256)])))
	Next
	Return $res
EndFunc