What is a Symmetric Key?
In cryptography, a symmetric key is one that is used for encryption, decryption, and message authentication. This practice, which is also referred to as ‘secret key cryptography’, means that to decrypt information, one must have the same key that was used to encrypt it. The keys, in practice, represent a shared secret between parties that can be used to maintain a private information link. The keys can be used by two or more parties. They can also be used by just one party (e.g. for the purpose of encrypting backups).
One benefit of symmetric cryptography is that it is notably faster than asymmetric cryptography. A well-known example of a symmetric cryptographic use case is tokenisation.