Pretty-Good-Privacy encryption system
|
_ (a) A user can encrypt a message so that only the desired addressee can read it. For example, Bob wants to send a message to Alice and make sure that only she will be able to read it. He then takes Alice’s public (black) key and encrypts the message, which will travel encrypted through the Internet. Once Alice receives the message, she can decipher it using her private (white) key. Although a third person may be able to intercept the message, he would not be able to decipher it because he would need Alice’s private key. (b) A user can digitally authenticate a message so that the recipient of the information can verify the authenticity of the information’s origin. For example, Alice wants to send a message to Bob and wants to make sure that he knows with absolute certainty that she is the sender of the message. To this end, she encrypts the message with her private key. If Bob is able to decipher it using Alice’s public key, then the message must have originated with Alice’s private key and, moreover, the message must be intact. |
Albert Díaz-Guilera