I have PHP using mcrypt ok for 3DES and RC2 algorithms, but when I ask for "arcfour", "ARCFOUR", or MCRYPT_ARCFOUR, it fails with "mcrypt_module_open(): Could not open encryption module". Yet checking our mcrypt installation (version 2.6.something - Arcfour support came in version 2.4), it lists arcfour as being among its supported algorithms, and it works at the command line. Could this be a problem on the PHP side?
