MD2 Hash Generator

What the MD2 generator does

This produces the MD2 hash of your text, a 32-character hex fingerprint. Type or paste your text, press Convert, and copy or download the result. MD2 is the oldest of the Message Digest hashes still seen in tools, a relic of a different era of computing, and like the rest of its family 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 32-character MD2 hash appears, ready to Copy or Download.

A hash built for 8-bit computers

MD2 dates from 1989, and its design tells you exactly when it was born. It was built for 8-bit machines, the small processors common at the time, so it works through data one byte at a time in a way that suited that hardware. That choice is also why it stands slightly apart from its younger relatives: where MD4 and MD5 follow one common internal pattern, MD2 is put together differently inside. It produces the same 128-bit, 32-character fingerprint they do, but it gets there by its own route. For a while it saw real use, including inside some early public-key certificates back when secure connections were first being built out.

Slow, broken, and retired

Two things ended MD2's working life. The first is simply speed. Being tuned for 8-bit machines, it is slow on modern hardware, slower than MD4, MD5, and the SHA family, so even setting security aside there is no performance reason to pick it. The second is security: researchers found practical attacks against it, undermining the guarantees a hash is supposed to provide. As with its siblings, the standards bodies formally moved MD2 to historic, obsolete status. It belongs here for historical interest and for reproducing the output of old systems that used it, nothing more. For real work, the SHA-256 page points the way.

The library doing the work

The hashing is handled by js-md2, a small JavaScript implementation of MD2. Your text is read as bytes and run through the algorithm in your browser, with the 32-character hex result handed back.

Questions people ask

Is MD2 safe to use?

No. It has practical attacks against it and has been formally retired. It is also slow. Use it only for historical interest or to match an old system, never for security.

How is MD2 different from MD4 and MD5?

It was designed for 8-bit machines and is built differently inside, working a byte at a time. It is also notably slower, while producing the same 32-character length of fingerprint.

Can I reverse an MD2 hash?

No. Like every hash in this family it is one-way, so the original text cannot be recovered. The MD5 page explains why.

References

1. Kaliski, B. (1992). RFC 1319: The MD2 Message-Digest Algorithm. Internet Engineering Task Force (IETF). https://www.rfc-editor.org/rfc/rfc1319
2. Turner, S., Chen, L. (2011). RFC 6149: MD2 to Historic Status. Internet Engineering Task Force (IETF). https://www.rfc-editor.org/rfc/rfc6149
3. js-md2, an MD2 implementation for JavaScript (npm package). https://www.npmjs.com/package/js-md2