a single key that is used for both encryption and decryption
the key that is used to encrypt a file or message is the same key that is used to decrypt the file or message.
One key that can be used to encrypt and decrypt the same data. Symmetric key encryption is different from public key encryption, which relies on one key held privately (for signing or decryption) and a second key distributed to the public (for signature verification or encryption).
The key that is used to encrypt a file or message in a symmetric cryptographic algorithm.