Secret Key

What Does Secret Key Mean?

A secret key is the piece of information or parameter that is used to encrypt and decrypt messages in a symmetric, or secret-key, encryption.


In assymetric encryption, two separate keys are used. One is a public key and the other is a secret key.

A secret key may also be known as a private key.

Techopedia Explains Secret Key

When using symmetric encryption, only one key is used for encryption and decryption. However, in asymmetric cryptography there is both a private key and a public key involved in the encryption and decryption processes. The secret key can be kept by one person or exchanged with someone else when sending encrypted messages. If only one key is available for both encryption and decryption, both the sender and receiver of a message have to have a copy of the secret key to be able to read the message.

The most difficult aspect of this type of encryption is how to distribute the key to a second party without affecting security.

Secret key cryptography systems are often classified to be either stream ciphers or block ciphers. Stream ciphers work on a single bit at a time and also use some kind of feedback mechanism so that the key changes regularly. A block cipher, on the other hand, encrypts one data block at a time by using precisely the same key on every block.

The most accepted secret key cryptography scheme is Data Encryption Standard (DES) cryptography. Other cryptography systems used for secret-key encryption include the Advanced Encryption Standard (AES) and CAST-128/256.


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Margaret Rouse
Technology Expert

Margaret is an award-winning technical writer and teacher known for her ability to explain complex technical subjects to a non-technical business audience. Over the past twenty years, her IT definitions have been published by Que in an encyclopedia of technology terms and cited in articles by the New York Times, Time Magazine, USA Today, ZDNet, PC Magazine, and Discovery Magazine. She joined Techopedia in 2011. Margaret's idea of a fun day is helping IT and business professionals learn to speak each other’s highly specialized languages.