These are just bare bones installation instructions.

Normally, `make' should be enough to build these tools.
A simpler version can be built by using `make check_sign' 
(does not depend on the existence of getpass())

You should define PGP in the Makefile if the default
(/usr/local/bin/pgp) doesn't apply.

There is no install target, just copy pkg_sign and/or check_sign where
you want, along with the manpage.

You need to install pgp by yourself. This should be pgp 2.63,
as these tools won't work with pgp5.

A standard Unix environment is assumed. Common functions such
as getopt() or strdup() should be obtained from another free software
package such as libiberty if not available on your platform.

These tools won't work on Unix-lookalike that don't provide fork()
or popen()  without some extensive modifications.