What encryption/decryption methods can I use in PHP?

PHP supported ciphers.

On Aplus.NET's servers PHP is compiled with "mcrypt" which supports the following ciphers:

cast-128
gost
rijndael-128
twofish
arcfour
cast-256
loki97
rijndael-192
saferplus
wake
blowfish-compat
des
rijndael-256
serpent
xtea
blowfish
enigma
rc2
tripledes

For more information on how to you use those please visit: http://www.php.net.