Ron Rivest and Jacob Schuldt have proposed replacing RC4 with an improved and slightly modified version dubbed Spritz.

<?php /** * @author www.Tutorialspots.com * @copyright 2017 */ function spritz($str, $key) { //Key-scheduling algorithm (KSA) for ($s = array(), $i = 0; $i < 256; $i++) $s[$i] = $i; for ($j = 0, $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; } //Pseudo-random generation algorithm (PRGA) $w = 1; for ($z = 0, $k = 0, $i = 0, $j = 0, $res = '', $y = 0; $y < strlen($str); $y++) { $i = ($i + $w) % 256; $j = ($k + $s[($j + $s[$i]) % 256]) % 256; $k = ($k + $i + $s[$j]) % 256; $x = $s[$i]; $s[$i] = $s[$j]; $s[$j] = $x; $z = $s[($j + $s[($i + $s[($z + $k) % 256]) % 256]) % 256]; $res .= $str[$y] ^ chr($z); } return $res; } ?>

The value *w*, is relatively prime to the size of the S array (256). We choose *w=1*. You can choose any odd value like 1,3,5,7,9…

**Javascript:**

function spritz(t, e) { var i, n, r, a, s, o, z, k, w; for (i = [], n = 0, a = "", s = 0; s < 256; s++) i[s] = s; for (s = 0; s < 256; s++) n = (n + i[s] + e.charCodeAt((s % e.length))) % 256, r = i[s], i[s] = i[n], i[n] = (r); for (w = 1, z = 0, k = 0, s = 0, n = 0, o = 0; o < t.length; o++) s = (s + w) % 256, n = (k + i[(n + i[s]) % 256]) % 256, k = (k + s + i[s]) % 256, r = i[s], i[s] = i[n], i[n] = r, z = i[(n + i[(s + i[(z + k) % 256]) % 256]) % 256], a += String.fromCharCode(t.charCodeAt(o) ^ z); return a }

*Example:*

alert(spritz(spritz('www.tutorialspots.com', 'tutorialspots'), 'tutorialspots'))

*Result:*

www.tutorialspots.com