PGP Encryption/Decryption issue & Integrity methods

Question

We had a process that ran for almost 3 years with no problems until last week.

We tried to generate an encrypted file and it successfully made it, but on decryption, it gave us this error:

It's not possible to decrypt this message because your keyring does not contain usable private key(s) corresponding to any of the above public key(s).

How can I fix this problem?

Also, After this error, we're trying now to add some Integrity Check for the encrypted files, so, is there any thing that I can do with pgp's .exe file(s) to do so? Or what else should I do with my code to make this thing work?

Answer 1

OpenPGP uses Public-Key-Encryption. This means you're handing out your public key (thus it's named public) for others to encrypt information targeted to you and only the holder of the private key (here: you) can decrypt it.

The error message is quite clear: You encrypted the file using a public key for which you haven't got the private key in your keyring. You will need to import it; if you haven't got it (any more), you cannot decrypt the file.

If you're using Symantec PGP, you can do it using

pgp --import <keyname.asc>

For GnuPG, just replace the pgp by gpg.

Your encrypted file will be probably allright, PGP could read it, otherwise it would have echoed another error message.