We cannot produce an input that produces an arbitrary given hash. Here's an easy counterexample: the all-zeroes md5sum. That's an even harder problem than the o

We cannot produce an input that produces an arbitrary given hash. Here's an easy counterexample: the all-zeroes md5sum. That's an even harder problem than the one I've claimed is entirely not solved. MD5 is still preimage and second-preimage resistant.