In
information security, message authentication or data origin authentication is a property that a message has not been modified while in transit (
data integrity) and that the receiving party can verify the source of the message.
Message
authentication does not necessarily include the property of
non-repudiation.
Message authentication is typically achieved by using
message authentication code
In cryptography, a message authentication code (MAC), sometimes known as a ''tag'', is a short piece of information used for authenticating a message. In other words, to confirm that the message came from the stated sender (its authenticity) and ...
s (MACs),
authenticated encryption (AE) or
digital signature
A digital signature is a mathematical scheme for verifying the authenticity of digital messages or documents. A valid digital signature, where the prerequisites are satisfied, gives a recipient very high confidence that the message was created b ...
s.
The message authentication code, also known as digital authenticator, is used as an integrity check based on a secret key shared by two parties to authenticate information transmitted between them. It is based on using a
cryptographic hash or
symmetric encryption algorithm. The authentication key is only shared by exactly two parties (e.g. communicating devices), and the authentication will fail in the existence of a third party possessing the key since the
algorithm will no longer be able to detect
forgeries (i.e. to be able to validate the unique source of the message).
In addition, the key must also be randomly generated to avoid its recovery through brute-force searches and related-key attacks designed to identify it from the messages transiting the medium.
Some cryptographers distinguish between "message authentication without secrecy" systems – which allow the intended receiver to verify the source of the message, but they don't bother hiding the plaintext contents of the message – from
authenticated encryption systems. Some cryptographers have researched
subliminal channel systems that send messages that appear to use a "message authentication without secrecy" system, but in fact also transmit a secret message.
Data origin authentication and non-repudiation have been also studied in the framework of quantum cryptography.
See also
*
Data integrity
*
Authentication
*
Deniable authentication In cryptography, deniable authentication refers to message authentication between a set of participants where the participants themselves can be confident in the authenticity of the messages, but it cannot be proved to a third party after the event. ...
References
Error detection and correction
Theory of cryptography
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