Decrypt Des file - then encrypt

Help..
I need to decrypt a file that was encrypted using DES 56 Bit.
I have the encryption key and the block size used but no idea what utility to use..

I then need to encrypt the file using pgp and another key I have.. againt I dont know what utility to use.

I am running solaris 9 ....

Any help would be appreciated. I understand how encryption works etc but dont know what utilities or commands to use on solaris to do this...