A symmetric key is an
|“||[e]ncryption methodology in which the encryptor and decryptor use the same key, which must be kept secret.||”|
|“||[a] cryptographic key that is used to perform both the cryptographic operation and its inverse, for example to encrypt plaintext and decrypt ciphertext, or create a message authentication code and to verify the code.||”|
Both the sending and receiving parties must know the secret key that they will use to communicate. Secret-key algorithms can encrypt and decrypt relatively quickly, but systems that use only secret keys can be difficult to manage because they require a courier, registered mail, or other secure means for distributing keys.
- Comm. on Nat'l Security Sys., National Information Assurance Glossary 58 (Inst. No. 4009 (2006)).
- NICCS, Explore Terms: A Glossary of Common Cybersecurity Terminology (full-text).