How do you encrypt parts of a file separately using pgp?

Question

I would like to encrypt credit card numbers on a web server as they come in using PGP. I would then like to be able to export all of the credit card numbers and other information in one file that can be easily decrypted using standard PGP software.

Is it possible to take the encrypted credit card numbers and join them with other encrypted data and be able to decrypt the entire file?

Basically is this true? D(E(x) + E(y)) = x + y

Where '+' means string concatenation.

Answer 1

It depends on which software you will use for decryption, and if it will handle multiple PGP messages in one stream.