Ten years ago I purchased a license to PGP 8.1 from its original publisher. As luck would happen, I hardly ever used it, and since then I have migrated my OS, etc., and my original installation is no longer available. I want to replace it with a Linux equivalent, and I am hoping that I can still use my old keys, which I still have. First, are the old keys compatible with any or all of the Linux PGP-based encryption products? Also, how do I import my own keys, especially the private key? I have one program installed: gpg (GnuPG) 1.4.16, and it would be convenient to use this one, but I'm open to others. I think that I imported my public key into ~/.gnupg/pubring.gpg, but I can't figure out how to get GnuPG to use or prompt me for my private key, and when I type ...
$ gpg filename
... I get the error message: "gpg: decryption failed: secret key not available".
Any suggestions would be appreciated.
Tom

We moved from pgp on HP-UX Unix to gpg on RHEL Linux back in 2013.

All you need to do is copy your public and private keyrings from the user(s) on your old system to the equivalent user(s) on your new system. You can then use "gpg --import <keyring_file>" to import the keyrings.

e.g.
To import private (secret) keyring file:
gpg --import secring.skr

To import public keyring file:
gpg --import pubring.pkr

NB: As noted above the keyrings are stored and imported for specific users rather than globally. If you want to import the keyring to user, billybob, you'd want to "su - billybob" before running the import. Obviously the copied in keyring file has be owned by the user you're doing the import as. (You should NOT have global permissions on keyring files for obvious reasons.)

Note that the syntax for gpg encryption, signing and decryption is slightly different than pgp.

You might also consider planning on updating your keys with whatever 3rd parties you've given your public keys to as 10 year old keys likely use lesser cypher strength than newer ones but you can do that after the imports by simply creating new keys and providing those to whoever has your old keys.

Edit: On reread I see you apparently did import your public keyring. You also need to import your secret keyring.

Hello Mensa Water,
Thank you for your reply. I still can't import the private key.
Public key appears OK:
horse[tom]: /home/tom/.gnupg$ gpg --list-keys
/home/tom/.gnupg/pubring.gpg
----------------------------
pub 1024D/0273F576 2005-01-05
uid Thomas Hedden <my@email.address.zzz>
sub 2048g/604B3AE2 2005-01-05

horse[tom]: /home/tom/.gnupg$ gpg --import secring.skr
gpg: no valid OpenPGP data found.
gpg: Total number processed: 0

What I did is to type my private key into a file
that I gave the right name to, then executed the
command that you suggested.

I suspect that the problem has to do with the format
of the file secring.skr, however I don't know what
the correct format is. That is, the public key has
the following structure:
-----BEGIN PGP PUBLIC KEY BLOCK-----
Version: PGP 8.1
[characters of public key ]
-----END PGP PUBLIC KEY BLOCK-----
The private key file that I am using just has the key,
not "BEGIN" or "END" lines. Do you (or anyone else)
know whether there is a structure for the private key
file, and if so, what it is?
Thanks in advance for any help.
Tom

For a private key I generated I see the multiple lines of the private key encapsulated like this:

If I run "file" against that individually stored key file it shows it as an ASCII file.

If I run "file" against my original pgp keyring file it displays as: PGP key security ring
The format of the keyring file is different than the above.

You can import an individual ASCII secret key into your key ring with:
gpg --import ./<sec_key_ascii_file>