MD6 Hash Generator

What the MD6 generator does

This produces the MD6 hash of your text, here a 64-character hex fingerprint. Type or paste your text, press Convert, and copy or download the result. MD6 is the odd one out of the Message Digest family, and its story is quite different from MD2, MD4, and MD5, as the sections below explain. Like every hash, it cannot be reversed back into your text.

It runs in your browser, so nothing you enter is uploaded.

How to use it

1. Enter your text. Type or paste it, or upload a plain text file.
2. Press Convert. The 64-character MD6 hash appears, ready to Copy or Download.

Not like the other MD hashes

It would be easy to assume MD6 is just the next broken old hash after MD5, and that would be wrong on every count. MD2, MD4, and MD5 are products of around 1990 that have since been broken. MD6 is from 2008, nearly two decades later, and it was a far more modern and ambitious design. Rather than working through data in a single chain like its predecessors, MD6 is built as a tree, so the work can be split across many processor cores at once, which suited the multi-core machines that were arriving. It also lets you ask for different output lengths; this tool produces a 256-bit, 64-character digest. So the shared "MD" name hides a big gap: this is a different generation entirely.

The hash that ran for SHA-3 and bowed out

MD6 was created for a specific occasion. When NIST ran its open competition to choose SHA-3, the contest described on the SHA3-256 page, Ronald Rivest entered MD6 as a candidate. It did not win, and it did not even advance to the second round, but the reason is the interesting part. In 2009 Rivest's team stepped back, explaining that to make MD6 fast enough to compete they would have had to cut its internal rounds down to a point where they could no longer prove it resisted a certain class of attack, and they were not willing to put it forward without that proof. Tellingly, no one had actually broken MD6. It was withdrawn out of caution, not because it failed. Keccak went on to become SHA-3, and MD6 became a respected design that never found a real job.

What that means for using it

So MD6 sits in an unusual spot. It is not broken the way the older MD hashes are, but it was never standardised, never widely reviewed in deployment, and never adopted, so it has none of the long track record that makes a hash trustworthy in practice. For any real work, the sensible choice is a vetted standard like SHA-256 or SHA-3, not MD6. Think of this tool as a way to meet an interesting and unusual piece of cryptographic history, and to reproduce MD6 output if you happen to need it, rather than as something to build on.

The library doing the work

The hashing is handled by an MD6 implementation written for JavaScript, which runs the algorithm in your browser and hands back the 64-character hex result. Because MD6 never became a common standard, it does not have the polished, widely used libraries that the mainstream hashes enjoy.

Questions people ask

Is MD6 broken like MD5?

No. No practical attack on MD6 is known. It is unbroken but also unadopted, which is a different situation from MD5, which is broken but still widely used.

Should I use MD6 for real work?

No. It was never standardised or widely vetted in practice, so it lacks the track record that makes a hash trustworthy. Use SHA-256 or SHA-3 instead.

What is its connection to SHA-3?

MD6 was entered into the NIST competition that chose SHA-3, but it was withdrawn before the second round. The winner, Keccak, became SHA-3.

Can I reverse an MD6 hash?

No. Like every hash it is one-way, so the original text cannot be recovered from it.

References

1. Schneier, B. (2009). MD6 Withdrawn from SHA-3 Competition. Schneier on Security. https://www.schneier.com/blog/archives/2009/07/md6.html
2. MD6. Wikipedia. https://en.wikipedia.org/wiki/MD6