Nope. See this paper: https://www.iacr.org/archive/crypto2004/31520306/multicollisions.pdf https://www.iacr.org/archive/crypto2004/31520306/multicollis... > I

Nope. See this paper: https://www.iacr.org/archive/crypto2004/31520306/multicollisions.pdf https://www.iacr.org/archive/crypto2004/31520306/multicollis... > If F and G are good iterated hash functions with no attack better than the generic birthday paradox attack, we claim that the hash function F||G obtained by concatenating F and G is not really more secure that F or G by itself.