CompTIA Security+ All-in-One Exam Guide (Exam SY0-301), 3rd Edition, 3rd Edition

Asymmetric Encryption

Asymmetric cryptography is in many ways completely different than symmetric cryptography. While both are used to keep data from being seen by unauthorized users, asymmetric cryptography uses two keys instead of one. It was invented by Whitfield Diffie and Martin Hellman in 1975. Asymmetric cryptography is more commonly known as public key cryptography. The system uses a pair of keys: a private key that is kept secret and a public key that can be sent to anyone. The system’s security relies upon resistance to deducing one key, given the other, and thus retrieving the plaintext from the ciphertext.

Public key systems typically work by using hard math problems. One of the more common methods is through the difficulty of factoring ...