# Which MAC scheme is quantum resistant?

will HMAC survive Grover algorithm ? if not then which MAC scheme provide post-quantum security ?

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Yes, HMAC with a sufficiently long key will survive Grover's algorithm. Grover's algorithm breaks a cryptosystem with a $n$-bit key using $2^{n/2}$ (quantum) steps of computation. Therefore, in practice, a 128-bit key is likely to survive Grover's algorithm, and a 160-bit key almost surely will.