Asymmetric Encryption
Asymmetric encryption, or public key cryptography, is different from symmetric encryption. It overcomes one of the big barriers of symmetric encryption: key distribution. Asymmetric encryption uses two unique keys, as shown in Figure 1.3. What one key does, the other key undoes.
Here’s how asymmetric encryption works: Imagine that you want to send a coworker a message. You use your coworker’s public key to encrypt the message. Your coworker receives the message and uses a private key to decrypt it.
Public key cryptography is made possible by the use of one-way functions. A one-way function, or trapdoor, is a math operation that is easy to compute in one direction, yet it is almost impossible to compute in the other direction. Depending on the type of asymmetric encryption used, this difficulty is based on either the discrete logarithm problem or the factoring of a large number into its prime factors. Although the...