The "crack" for MD5 isn't really a crack. The algorithm, given a file and its MD5, will tell you which bits you can change in the file without affecting the MD5. There is not known algorithm that will let you create or alter an arbitrary file to match a given MD5.

The SHA1 "crack" isn't really a crack, either. It's just a weakness in the algorithm that allows you to reduce the space that you do a brute force attack in by a factor of 131072.