Basic Cryptography: Asymmetric Key Encryption

Abstract

We previously mentioned a second type of encryption called asymmetric key (or public/private key) cryptography. This is much more recent than symmetric key, and involves some complex math. It is far slower than symmetric key, hence not suitable for encryption of large documents (normally it only encrypts 128 to 512 bits). It is however, well suited to key management. Unlike symmetric key that uses the same key for encryption and decryption, asymmetric key uses a matched pair of keys (one public, one private) for each user. This is not intuitive as is symmetric key. You don’t lock you house with one key and unlock it with a different key. Asymmetric key cryptography is central to many real-world cryptographic systems.