Quote from: Kazimir on June 11, 2012, 12:24:36 PM

Quote from: Meni Rosenfeld on June 11, 2012, 12:15:53 PM

I did a calculation which says that every application of SHA-256 reduces entropy by about 0.5734 bits. I have no idea if that's correct.

Ah, interesting. Well if that's true, the problem seems insignificant, although it could have been prevented entirely by an approach like I posted above (just an example, obviously there are numerous alternatives). And still covering the vulnerability for potential cracks in sha256.

no! the number is wrong, the entropy after 512 rounds of sha256, will be below 0, if its true. which is not good or insignificant. its a huge error.

a acceptable reduction would be around 10^-80 bits/round

sorry dude you did your math wrong.