Quote from: pusle on June 11, 2012, 11:27:42 AM

The way I understand it is that adding more rounds makes it harder to find a short cut/weakness.
The fixed length for the second sha256 stage also removes one type of "attack" often used against such algorithms.

OK, nonetheless I don't see any demerits (yet it does overcome certain risks) from using the alternative double hashing scheme I mentioned above. Or more generally:

Code:

Hash(input,depth) :=
Hash(input) if depth==1
Hash(Hash(input)+input,depth-1) otherwise

(where 'Hash' can be any regular hashing function, such as sha256)