- rot13 rot12
- http://www.w3schools.com/php/func_string_crypt.asp
- http://en.wikipedia.org/wiki/RC4
- http://www.alltextencryption.com/
- http://php.net/manual/en/book.mcrypt.php
- http://php.net/manual/en/function.openssl-encrypt.php
- http://php.about.com/od/advancedphp/ss/encryption.htm
- http://www.stevenmcmillan.co.uk/blog/2012/php-easy-aes-encryption-class/
- md5
- sha1
- http://www.tools4noobs.com/online_tools/encrypt/