SHA-3 for Message Authentication Code

By Ali Mohammad

Details: -- BSc. Computer Science

Published: May 09, 2024 19:06

To use SHA-3 for Message Authentication Code (MAC), you need to implement the HMAC (Hash-based Message Authentication Code) construction by combining a secret key with the message and hashing the result using SHA-3. Specifically, you start by padding the secret key to the block size of the hash function if necessary, then compute an inner hash using the key and the message, and finally compute the outer hash by hashing the inner hash with a different key padding. This process ensures data integrity and authenticity, as both the sender and receiver must have the same secret key to verify the MAC.

For digital signatures, SHA-3 is used to hash the message to create a fixed-size digest, which is then encrypted with the sender's private key to generate the signature. The recipient, upon receiving the signed message, decrypts the signature using the sender's public key to retrieve the original message digest. The recipient also hashes the received message using SHA-3 and compares this computed digest with the decrypted digest. If they match, the signature is verified, confirming the message's authenticity and integrity.

To use SHA-3 for a Message Authentication Code (MAC), implement HMAC by combining a secret key with the message and hashing the result with SHA-3 to ensure data integrity and authenticity. For digital signatures, hash the message with SHA-3 to create a digest, encrypt it with the sender's private key to generate the signature, and verify it by decrypting with the sender's public key and comparing it to the hash of the received message.