SHA512/256 Hash Generator

What the SHA-512/256 generator does

This produces the SHA-512/256 hash of your text, a 64-character hex fingerprint. Type or paste your text, press Convert, and copy or download the result. Despite the name, it is a member of the SHA-2 family, and like every hash it is one-way, so the result cannot be turned 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 SHA-512/256 hash appears, ready to Copy or Download.

What SHA-512/256 actually is

The name reads like a fraction, and it almost is one. SHA-512/256 means: run the full SHA-512 algorithm, then keep only the first 256 bits of the result. So it uses SHA-512's big 64-bit engine, the one covered on the SHA-512 page, but hands you a shorter, 64-character fingerprint instead of the full 128. It is not a plain chop, though. It starts the calculation from its own special set of internal seed values, so its hash of a given text is genuinely its own value, not just the front half of that text's SHA-512.

It is not the same as SHA-256

This is the point to hold onto, because SHA-512/256 and SHA-256 both give a 256-bit, 64-character hash, and it is easy to assume they are the same. They are not. They are built on different engines, SHA-512's 64-bit machinery versus SHA-256's 32-bit machinery, and they start from different seed values, so the same text produces two entirely different results. The matching length is a coincidence of the output size, not a sign they are interchangeable.

Two real reasons it exists

It would be fair to ask why anyone needs a 256-bit hash carved out of SHA-512 when SHA-256 already exists. There are two genuine reasons. The first is speed, on the right hardware. SHA-512's engine is built for 64-bit processors, and on a modern 64-bit machine it often runs faster than SHA-256's 32-bit engine. So SHA-512/256 can give you a 256-bit fingerprint at that faster pace. The second is a security bonus: because the output is trimmed, the full internal state is never exposed, which makes SHA-512/256 naturally resistant to a subtle weakness called the length-extension attack that plain SHA-256 has to guard against. For someone who wants a fast, 256-bit, length-extension-safe hash, this is a quietly excellent option.

The library doing the work

The hashing is handled by js-sha512, a small JavaScript library implementing the 64-bit SHA-2 engine, which also provides SHA-512/256. Your text is read as UTF-8 bytes and run through the algorithm in your browser, with the 64-character hex result handed back.

Questions people ask

Is SHA-512/256 the same as SHA-256?

No. Both give a 64-character hash, but they use different engines and different seed values, so the same input produces different results. They are not interchangeable.

Why use it instead of SHA-256?

For two reasons: on 64-bit hardware it can be faster, and because its output is trimmed it resists length-extension attacks that plain SHA-256 does not.

Can I reverse a SHA-512/256 hash?

No. It is one-way, so the original text cannot be recovered. The SHA-256 page explains why no hash can be reversed.

References

1. National Institute of Standards and Technology (2015). FIPS PUB 180-4: Secure Hash Standard (SHS). https://nvlpubs.nist.gov/nistpubs/FIPS/NIST.FIPS.180-4.pdf
2. js-sha512, a SHA-512 implementation for JavaScript that also provides SHA-512/256 (npm package). https://www.npmjs.com/package/js-sha512