In: Computer Science
Is MD5 hash function is indistinguishable and non-malleable? Explain it.
Yes, Message Digest 5 (MD5) hash function is indistinguishable
and non-malleable. The two desirable properties of a hash
function are:
1) Pseudo-random: The function behaves
indistinguishably from a random oracle.
2) Non-malleability: With J(x), it is difficult
for generating J(f(x)) for any function f. Malleability is the
expander hash design's inherent property. Malleability properties
show negative implications for certain hash functions applications'
security however, for Cayley hashes though, they give rise to
efficient parallel computation algorithms.
MD5 cryptographic hash function should be computationally infeasible to find two distinct messages hashing to the same value however, MD5 fails catastrophically in this regard, unable to meet this requirement.
Thus, a hash function should be indistinguishable from a pseudorandom function and unforgeable or non-malleable when used as a MAC.