Description: HMAC-SHA256 is a specific type of HMAC that uses the SHA-256 hash function. HMAC, which stands for ‘Hash-based Message Authentication Code’, is an authentication mechanism that combines a cryptographic hash function with a secret key. The SHA-256 function, part of the SHA-2 family, produces a 256-bit hash and is known for its collision resistance and security in data integrity. HMAC-SHA256 is used to verify both the integrity and authenticity of a message, ensuring that it has not been altered and that it comes from a trusted source. This method is widely used in various security protocols, including TLS and HTTPS, and in message signing across different applications and data storage solutions. Its design allows HMAC-SHA256 to be efficient and secure, making it a popular choice in modern cryptography.
History: HMAC was proposed in 1996 by Mihir Bellare, Ran Canetti, and Hugo Krawczyk in a paper titled ‘Keyed Hash Functions and Their Use in Message Authentication’. The SHA-256 function was introduced in 2001 as part of the SHA-2 family, developed by the National Security Agency (NSA) of the USA. HMAC-SHA256 combines these two developments, providing a robust method for message authentication in digital environments.
Uses: HMAC-SHA256 is used in various security applications, including message authentication in network protocols, digital signing of documents, and integrity verification in storage systems. It is also common in APIs to ensure that requests come from authorized sources.
Examples: An example of using HMAC-SHA256 is in authenticating requests in REST APIs, where a hash of the request content along with a secret key is generated to verify the authenticity of the sender. Another example is in the implementation of access tokens in authentication systems, where HMAC-SHA256 is used to sign tokens and ensure their integrity.
