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3

There is work underway to specify KMAC. It's basically just SHA-3, but with a length specification for the key and a special value to indicate that this is KMAC instead of hashing. These constructions are required to make sure that there are no unfortunate collisions with previously hashed data or - more importantly - key / message pairs where $H(K_1,M_1) = ...


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[I would rather put this as a comment but my 'reputation' is not high enough to allow comments]. the information must be authentic and fresh Not sure what is meant by 'fresh' in this context. Anyway, given that both the 'device' and the 'source' are capable of storing a secret key, first thing that springs to mind is a protocol based on a symmetric ...


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As I have a new hash every 3 second, it's easy for everyone to collect a big numbers of hash. And as the difference between every UUID is always 3000 ms, maybe this could make it easier for the hacker to crack the key. You might be reassured to read up on the security requirements that MACs are designed for. Chapter 9 of the Handbook of Applied ...


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HMAC-SHA256 is extremely safe. In the question's use, the key is large (48 characters, likely >160 bits of entropy). From a theoretical standpoint, everything checks. HMAC is demonstrably resistant (to 128-bit level) even if an adversary can obtain the MAC of chosen messages, under weak hypothesis for SHA-256 (see M. Bellare: New Proofs for NMAC and HMAC: ...



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