In this guide, I will explain the options at your disposal for encrypting files using open-source software on a Linux, Mac, or Windows computer. You can then transport this digital information across distance and time, to yourself or others.
The program “GNU Privacy Guard” (GPG) an open-source version of PGP (Pretty Good Privacy), allows:
- Encryption using a password.
- Secret messaging using public/private key cryptography
- Message/Data authentication (using digital signatures and verification)
- Private key authentication (used in Bitcoin)
Option One
Option one is what I’ll be demonstrating below. You can encrypt a file using any password you like. Any person with the password can then unlock (decrypt) the file to view it. The problem is, how do you send the password to someone in a secure way? We’re back to the original problem.
Option Two
Option two solves this dilemma (how-to here)[1]. Instead of locking the file with a password, we can lock it with someone’s public key — that “someone” is the intended recipient of the message. The public key comes from a corresponding private key, and the private key (which only the “someone” has) is used to unlock (decrypt) the message. With this method, no sensitive (unencrypted) information is ever sent. Very nice!
The public key is something that can be distributed over the internet safely. Mine is here[2], for example. They are usually sent to keyservers. Keyservers are like nodes that store public keys. They keep and synchronize copies of peoples’ public keys. Here’s one:
You can enter my email[4] and find my public key in the result. I’ve also stored it here[5] and you can compare what you found on the server.
Option Three
Option three is not about secret messages. It
