High score kneeling Beg asp/php string encryption decryption possible string base64

High score kneeling Beg asp/php string encryption decryption or string base64
For example:
Original URL string: http://wwww.adfasf.com/upload/20120304/4532524.jpg
I need to encrypt this string to: a short string, uppercase and lowercase letters + numbers or individual numbers or letters.

Example: "Http://wwww.adfasf.com/upload/20120304/4532524.jpg" = "AFADASFWETQETQWETFASDF" after encryption
The decryption program is also needed: when I get to "afadasfwetqetqwetfasdf", I get the original string by decrypting the program.

Example: "Afadasfwetqetqwetfasdf" = "http://wwww.adfasf.com/upload/20120304/4532524.jpg" after decryption

Thank you, prawns.

Program or Direct hair: danlan_sky@126.com

------Solution--------------------
Hero, you write a cryptographic algorithm.
That's the way it is done,

PHP code

php codefunction Valid () {(User name id*16-32) string connection time and input 
------Solution--------------------
 Out-of-the-box functions are not available? 
 
   
   

    
     PHP code 
    
    
 $url = "http://wwww.adfasf.com/upload/2012030 4/4532524.jpg "; $encrypt = Base64_encode ($url); $decrypt = Base64_decode ($encrypt); echo" Encrypt-->> ". $encrypt." 
 ";//ahr0cdovl3d3d3cuywrmyxnmlmnvbs91cgxvywqvmjaxmjazmdqvnduzmjuync5qcgc=echo" decrypt-->> ". $decrypt." 
 ";//http://wwww.adfasf.com/upload/20120304/4532524.jpg 
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