Enkripsi Asimetrik

First, Alice asks Bob to send his open padlock to her through regular mail, keeping his key to himself. When Alice receives it she uses it to lock a box containing her message, and sends the locked box to Bob. Bob can then unlock the box with his key and read the message from Alice. To reply, Bob must similarly get Alice’s open padlock to lock the box before sending it back to her.

The critical advantage in an asymmetric key system is that Bob and Alice never need to send a copy of their keys to each other. This prevents a third party (perhaps, in the example, a corrupt postal worker) from copying a key while it is in transit, allowing said third party to spy on all future messages sent between Alice and Bob. In addition, if Bob were careless and allowed someone else to copy his key, Alice’s messages to Bob would be compromised, but Alice’s messages to other people would remain secret, since the other people would be providing different padlocks for Alice to use.

Asymmetric encryption uses different keys for encryption and decryption. The message recipient creates a private key and a public key. The public key is distributed among the message senders and they use the public key to encrypt the message. The recipient uses their private key any encrypted messages that have been encrypted using the recipient’s public key.