PGP query with SDA

Hi
I have a requirement to have a script which will encrypt a file on my HPUX server in such a way that the receiver of the file only has to enter a passphrase to decrypt (no swapping of keys, etc.) Ideally, I want to use some free software to perform the task.

From what I have read so far, the way to do this involves encrypting it using PGP Self Decrypting Archive (SDA) which allows users to send conventionally encrypted files to people who do not have PGP installed.

However I don't know what tool to use on a HP-UX platform to achieve this. GnuGp might be the way to go, but I don't know if it supports SDA or how successful it is on HP-UX.

All advice welcome
TIA