HMACSHA2

HMACSHA2 is a type of keyed-hash message authentication code (HMAC) that utilizes the SHA-2 family of cryptographic hash functions. HMAC is a specific construction for calculating a message authentication code (MAC) involving a cryptographic hash function in combination with a secret cryptographic key. The SHA-2 family itself consists of several hash functions, including SHA-224, SHA-256, SHA-384, SHA-512, SHA-512/224, and SHA-512/256. When HMAC is used with one of these SHA-2 functions, it is often referred to as HMACSHA256, HMACSHA512, and so on, depending on the specific SHA-2 variant employed.

The purpose of HMACSHA2 is to simultaneously verify data integrity and authenticity. It ensures that a message has not been tampered with during transmission or storage, and it confirms that the message originated from a sender who possesses the secret key. This is achieved by combining the secret key with the message and then hashing the result using the chosen SHA-2 function. The output is a fixed-size tag that is appended to the message. A recipient who also possesses the secret key can recalculate the HMAC tag and compare it to the received tag. A match indicates that the message is authentic and has not been altered. HMACSHA2 is widely used in various security protocols and applications.