# Publicly exposed hash of private key

Would exposing a cryptographic hash function's digest (e.g. SHA-3) of RSA private key data compromise the key? If so, what are the possible (cryptanalysis-) vectors for attacking the key if an attacker had knowledge of this hash?

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Why are you wanting to do this, exactly? Offhand I cannot think of any real issues, but I suspect whatever you're using the digest for, there's probably a better way involving the public key. –  Reid Dec 1 '13 at 3:40

This does not compromise the private key as long as the hash function is preimage resistant, i.e. given $H(M)$ it is hard to find $M$ (or any $M'$ giving the same $H(M)$). SHA-3 is assumed to be preimage resistant.