Security Service: Encrypting Files With GnuPG
Seahorse…what an odd name for a GPG front-end… Ok, so I decided to finally get a GUI front-end for handing my GPG (GnuPG) needs, and There are several too choose from. The list can be found here. For today, I will be showing you just how to use GnuPG from the Termainl, as well as my GUI front-end of choice, Seahorse. Nayyyyyyyyyyyy, wait…do Seahorse’s make a sound? Damn you Saturday morning cartoons…
Read on for more…
What is a Public Key? A Private Key?
To put it simply you generate a pair of matched keys. One of these is known as your “Public” key, and the other as your “Private”key. You give the Public key to anyone who wants it; you can even put it out on the web if you wish. You keep your Private key secret, locked up on your own computer. A document (a text or binary file) can be encrypted using either key, and is decrypted with the other. The choice of which key to use to depends on what you are trying to accomplish.
For example, if you want to send me a super cool sample of your latest mix, you’d encrypt it using my public key. No one else can decrypt it my mix; only my private key will decrypt the file. The flipside to this is that I might be worried that it really is you sending me a message. In that case, you’d encrypt your message using your private key (this is called “signing“). If I can decrypt it with your public key (presumably I somehow obtained that key and trust that it really is yours), I know that the message really came from you. You do not need to “sign” files, but it is good measure for security
The encrypted document can only be decrypted by someone with a private key that complements one of the recipients’ public keys. In particular, you cannot decrypt a document encrypted by you unless you included your own public key in the recipient list.
Here is an illustration to explain:
Dave wants to send sensitive data to Jill, and wants to be sure that only Jill may be able to read it, he will encrypt the data with Jill’s Public Key. Only Jill has access to her corresponding Private Key and as a result is the only person with the capability of decrypting the encrypted data back into its original form. That public key Dave signed the file with directly corresponds to Alice’s private key. Hence, the two keys are intertwined.
|Sent using:||Needed to decrypt:|
|Public Key||Private Key|
|Private Key||Public Key|