Any reason for these encryption algorithms in particular? You could use a stronger algorithm, like those supported in Gnu's Privacy Guard (same as PGP) for free.
If you take a look out on sourceforge, you should be able to get ccrypt (I believe that it uses Rijndael) or sectar (an encrypting tar utility that uses AES). Haven't tried either of them, especially on an HPUX box, but I can't think of a reason off-hand why they would not compile.
Also, there is a Rijndog tool that also uses AES.
Good luck!
pansophic