Linux Desktop Hacks

Encrypt Your Email #57

Chapter 8, Desktop Programs

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181

HACK

One of the first things you will do is generate a keypair that is unique to

yourself. As the name suggests, two keys will be generated. One (the public

one) will be distributed to all your friends, and the other (the private one)

you must keep safe. Anything that is encrypted with your public key (the

one you distribute) can be decrypted only by your private key (the one you

have for safekeeping).

Here’s how the system works. When someone sends you an email message,

she encrypts it with your public key. When you receive the message, you

decrypt it with your private key. If anyone along the way intercepts the

encrypted email, they won’t be able to read it, because they don’t have your

private key. Likewise, when you send email to your friends, you should

encrypt the message with their public key. This is why it is important that

you share your public key with as many people as possible so that they can

send you encrypted email. You can also upload your public key to a key

server. These servers host public keys and give them to users who request

them so that they can send you a message.

In case you are wondering, by the way, the public and private keys are math-

ematically related, but having one doesn’t mean you can reverse-engineer it

to become the other. This fact is mathematically proven and is the heart of

any public/private key system. ...