mcrypt_ofb
    (PHP 3>= 3.0.8, PHP 4 )
mcrypt_ofb -- Encrypt/decrypt data in OFB mode
Description
string 
mcrypt_ofb ( int cipher, string key, string data, int mode, string iv)
string 
mcrypt_ofb ( string cipher, string key, string data, int mode [, string iv])
     The first prototype is when linked against libmcrypt 2.2.x, the
     second when linked against libmcrypt 2.4.x or higher.
    
     This function should not be used anymore, see
     mcrypt_generic() and
     mdecrypt_generic() for replacements.