diff --git a/Crypt.php b/Crypt.php
new file mode 100644
index 0000000..49e29fb
--- /dev/null
+++ b/Crypt.php
@@ -0,0 +1,219 @@
+<?php 
+
+namespace killua;
+
+final class Crypt0 {
+    
+    // a string of all alphanumeric characters
+	// used for random string generation
+	public static $S     = [];
+	public static $chars = '0123456789abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ';
+	public static $key   = 'yj21i6d6cO35efgDH43G4Pe3XSo7aEUcb4wiee1R574bdUY77Iv787fFta7Fwp86pA6b8U6'; 
+	
+    public static function encode_url( string $str ) : string {
+		$i       = -1;
+	    $encoded = '';
+
+	    while( ($i++) < mb_strlen( $str ) - 1 ){
+		    if( $str[$i] == ' ' ){
+			    $encoded .= '+';
+		    }
+		    else if( (ord( $str[$i] ) <= 57 && ord( $str[$i] ) >= 48)  || 
+				     (ord( $str[$i] ) >= 65 && ord( $str[$i] ) <= 90)  || 
+				     (ord( $str[$i] ) >= 97 && ord( $str[$i] ) <= 122) || 
+				     ( $str[$i] == '-' || $str[$i] == '_' || $str[$i] == '.' || $str[$i] == '~' ) ){
+
+			    $encoded .= $str[$i];
+		    } else{
+			    $encoded .= '%';
+				$encoded .= self::dec_2_hex( (int) ord( $str[$i] ) );
+		    }
+	    }
+	    return $encoded;
+    }
+
+
+    public static function decode_url( string $str ) : string {
+		$i       = -1;
+	    $decoded = '';
+	}
+	
+
+    public static function signature_generate() : string {
+	    $length 	= strlen( self::$chars );
+	    $signature  = '';
+	    $i			= 0;
+	    $fp         = fopen( '/dev/urandom', 'rb' );
+	    $f          = fread( $fp, strlen( self::$chars ) );
+
+	    while( ( $i++ ) < $length ) {
+		    if( $i % 4 == 0 ){
+			    $signature .= dechex( ord( $f[$i] ) );
+		    } else{
+			    $signature .= self::$chars[ mt_rand( 0, $length - 1 ) ];
+		    }
+	    }
+	    return substr( $signature, 0, strlen( $signature ) - 5 );
+    }
+
+
+	public static function dec_2_hex( int $dec_num ) : string {
+		$hex       = '';
+		$remainder = 0;
+		
+		while( (int) $dec_num != 0 ){
+			$remainder = $dec_num % 16;
+			if( $remainder <= 9 ){
+				$hex .= chr( $remainder + 48 );
+			} else{
+				$hex .= chr( $remainder + ( (48 << 1) - 9 ) );
+			}
+			$dec_num /= 16;
+		}
+		return strrev( $hex );
+	}
+
+
+	public static function hex_2_dec( string $hex_string ) : int {
+		$d          = 0;
+		$num        = 0;
+		$i          = strlen( $hex_string );
+		$hex_string = strrev( $hex_string );
+		
+		# remove leading '0x | 0X'
+		if ( strpos( $hex_string, '0x' ) === 0 || strpos( $hex_string, '0X' ) === 0 ) {
+			$hex_string = substr( $hex_string, 2 );
+		}
+		
+		while( ($i--) > 0 ){
+			if( ord( $hex_string[$i] ) >= 65 && ord( $hex_string[$i] ) <= 90 ){
+				$d    = ord( $hex_string[$i] ) - ord('A') + 10;
+				$num += (int) ($d * (16 ** $i));
+			}
+			else if( ord( $hex_string[$i] ) >= 97 && ord( $hex_string[$i] ) <= 122 ){
+				$d    = ord( $hex_string[$i] ) - ord('a') + 10;
+				$num += (int) ($d * (16 ** $i));
+			}
+			else{
+				$num += (int) ((int) $hex_string[$i] * (16 ** $i));
+			}
+		}
+		return $num;
+	}
+
+	# ROT13 cipher
+	public static function rot13 ( string $str ) : string {
+		$i      = -1;
+		$newStr = '';
+		while ( ($i++) < mb_strlen( $str ) - 1 ) {
+			if ( (ord($str[$i]) >= ord('A') && ord($str[$i]) <= ord('M') ) 
+			  || (ord($str[$i]) >= ord('a') && ord($str[$i]) <= ord('m') ) ) {
+				$newStr .= chr( ord( $str[$i] ) + 13 );
+			}
+			else if ( (ord($str[$i]) >= ord('N') && ord($str[$i]) <= ord('Z')) 
+				   || (ord($str[$i]) >= ord('n') && ord($str[$i]) <= ord('z')) ) {
+				$newStr .= chr( ord( $str[$i] ) - 13 );
+			}
+			else{
+				$newStr .= $str[$i];
+			}
+		}
+		return $newStr;
+	}
+	
+	# RC4
+	public function rc_crypt0( $key, &$S, $message ) {
+		$crypted = '';
+		for ( $i = 0 ; $i < 256 ; $i++ ) {
+			$S[$i] = (int) $i;
+		}
+		$j = 0;
+		for ( $i = 0 ; $i < 256 ; $i++ ) {
+			$j = ( $j + $S[$i] + ord( $key[ $i % strlen( $key ) ] ) ) % 256;
+			$temp  = $S[$i];
+			$S[$i] = $S[$j];
+			$S[$j] = $temp;
+		}
+		$i =  0;
+		$j =  0;
+		$x = -1;
+		while ( ($x++) < strlen( $message ) - 1 ) {
+			$i = ( $i + 1 ) % 256;
+			$j = ( $j + $S[$i] ) % 256;
+			$temp    = $S[$i];
+			$S[$i]   = $S[$j];
+			$S[$j]   = $temp;
+			$K       = $S[( $S[$i] + $S[$j] ) % 256];
+			$crypted[$x] = (string) chr( ord( $message[$x] ) ^ $K ); # XOR the current plaintext digit with the current 'S' digit
+		}
+
+		return $crypted;
+	}
+	
+	
+	public function code( $msg ) {
+		$res = '';
+		for ( $i = 0 ; $i < strlen( $msg ) ; $i++ ) {
+			$res[$i] = chr( (ord( $msg[$i] ) ^ 0x05) % 256 );
+		}
+		return $res;
+	}
+
+
+	public function cry0( string $msg, int $num ){
+		$str = '';
+		for ( $i = 0 ; $i < strlen( $msg ) ; $i++ ) {
+			$str[$i] = chr( ord( $msg[$i] ) - $num );
+		}
+		return $str;
+	}
+
+
+	public function cry1( string $msg, int $num ){
+		$str = '';
+		for ( $i = 0 ; $i < strlen( $msg ) ; $i++ ) {
+			$str[$i] = chr( ord( $msg[$i] ) + $num );
+		}
+		return $str;
+	}
+	
+	
+    public static function dec_2_bin( int $dec_num ) : string {
+        $i   = -1;
+        $bin = '';
+
+        while( $dec_num ){
+            $bin .= (string) ($dec_num & 1);
+            $dec_num >>= 1;
+        }
+        return strrev( $bin );
+	}
+
+
+	public function rnd_slt( string &$msg ){
+		
+	}
+}
+
+//echo \killua\Crypt0::dec_2_hex( 346777 );
+//echo \killua\Crypt0::hex_2_dec( '3a3' );
+//echo \killua\Crypt0::dec_2_hex( '931' );
+//echo \killua\Crypt0::dec_2_bin( 231 );
+//$a = \killua\Crypt0::code( 'what is that?' );
+//echo \killua\Crypt0::code( $a );
+//$a = \killua\Crypt0::cry0( 'what is that', 4 );
+//echo \killua\Crypt0::cry1( $a, 4 );
+
+//$key  = \killua\Crypt0::$key;
+//$msg0 = 'what the fuck man? my h0use is f0ken dead!';
+//$msg0 = "Holy sh1t man! that's fo0-ken awesome!?!$";
+
+//$a0   = \killua\Crypt0::rc_crypt0( $key, \killua\Crypt0::$S, $msg0 );
+//echo $a0 . "\x0a";
+
+//$b0 = \killua\Crypt0::rc_crypt0( $key, \killua\Crypt0::$S, $a0 );
+//echo $b0 . "\x0a";
+
+?>
+
+