4 ms·

Is this possible only because md5 is weak? Is it possible to do the same with sha2 or sha1?

• infofarmer 4y ago
  Yes. Not yet.
• googlryas 4y ago
  Yup - it's possible to do with any hash algorithm. You can also do it with any hash value. A key point here is that there are a ton of pixels in this image whose value can be changed slightly without disturbing the image. The # of variants possible quickly starts to dwarf the # of valid hash values possible, to the point where you can find the hash eventually, if you just keep looking.
  • posedge 4y ago
    Given that an md5 hash is 128 bit, by simple brute force, you would need to try 2^128 variants (in expectation) to find the matching hash. Thats rougly 10^38 combinations. That's a huge number, I can't imagine that the author simply hashed variants until one happened to match, there must habe been some other technique involved.