CISSP Training Kit

Cryptographic keys

Cryptography relies on keys. In symmetric key cryptography, the key that is used to encrypt the content is the same key that is used to decrypt the content. The sender and the recipient must each have a copy of the key to perform the encryption and decryption process, so these two copies must be identical.

In asymmetric key cryptography, often referred to as public key cryptography, a pair of related keys is used. One key is a private key, created and stored securely and never shared. The mathematically related key in the key pair is the public key. These keys are related such that what one key encrypts, only the other key can decrypt. If you encrypt using the private key, only the public key can decrypt the content. If you encrypt ...