Why MD5 passwords can not be resolved?

Question

Question is simple. Cypted md5 data need to be possible decrypt theoretically. Can anyone explain this.

Thanks.

MD5 is a (broken) hash algorithm that should not still be used for password hashing or any security critical purpose. It is not possible to 'decrypt' a hash algorithm — they're intended to be one-way functions. In principle, there are many different texts that could all hash to the same MD5 hash value. — Jonathan Leffler, Jan 08 '17 at 22:13

score 1 · Answer 1 · answered Jan 08 '17 at 21:47

Here's a similar example to MD5:

function superInsecureHash(string) {
  return string.length;
}

console.log(superInsecureHash("Hello world!")); // 12

Can you get from 12 back to "Hello world!" in any way? No, for similar reasons, you can't get back to the original from any proper hash function.

As it happens, though, MD5 is weak and broken. You shouldn't be using it at all, seek better alternatives.

1 Answers1