How do I migrate from PGP 2.x to GnuPG?
PGP 2 uses the RSA and IDEA encryption algorithms. Whereas the RSA patent has expired and RSA is included as of GnuPG 1.0.3, the IDEA algorithm is still patented until 2007. Under certain conditions you may use IDEA even today. In that case, you may refer to Question 3.3 about how to add IDEA support to GnuPG and read