2 ms·

Thanks for the answer. I am really not familiar with the mathematics of hash algorithms and I ask just to learn. Why is length essentially a weak hash? Isn't i

• Dylan16807 12y ago
  > Why is length essentially a weak hash? It's utterly trivial to match by itself. Adding length to a real hash is a mild difficulty increase. Adding a second hash is a massive difficulty increase. > Isn't it an additional constraint that works orthogonal to the hash? Yes. But so is a second hash. > It serves to restrict the space of collisions and hence directly reduces the exploit surface. Very inefficiently. > Moreover, the length can be independently verified of the hash function, and its space & time complexity is negligible. A second hash is independent of the first hash too. Hashing a second time compared to downloading and hashing the first time is pretty close to negligible.