Snefru Hash Generator
Turn any text into its 64-character Snefru hash instantly.
How to use the Snefru Hash Generator
- Type or paste your text in the box.
- The 64-character Snefru hash appears as you type.
- Click Copy to grab the result.
About the Snefru Hash Generator
Snefru was designed by Ralph Merkle — a name that turns up at the root of a startling amount of modern cryptography, from public-key exchange to the Merkle trees underpinning Git and every blockchain. Snefru is one of the earliest dedicated hash functions, built around a construction Merkle also gave his name to, and it produces 256 bits here: 64 hexadecimal characters. It is named after a pharaoh, following a small tradition of Merkle naming his designs after Egyptian rulers.
Its history is a genuinely useful cautionary tale rather than a footnote. Early versions of Snefru were broken by Eli Biham and Adi Shamir, using differential cryptanalysis — the same technique that reshaped how block ciphers were analysed. Merkle's response was to increase the number of passes the function makes over the data, which is the standard remedy: buy back security margin by doing more mixing. That episode is part of why cryptographers now treat "unbroken so far" and "designed with margin" as very different claims.
Today Snefru is a historical curiosity. It is slow by modern standards, it carries the reputational weight of having been broken once, and essentially nothing in production depends on it. This tool exists for reading legacy data, checking implementations against known values, and satisfying curiosity. One practical note: PHP exposes the names snefru and snefru256, and both produce the identical 256-bit hash — they are aliases, not two different functions. For anything real, use SHA-256 or SHA3-256.
Frequently asked questions
Can I decrypt or reverse a Snefru hash?
No. Snefru is a one-way hash — the original text is not contained in the output, so there is nothing to decrypt or extract.
What is the difference between "snefru" and "snefru256"?
In PHP, nothing — both names produce the identical 64-character 256-bit hash. They are aliases for the same function, which is why this tool does not offer a choice between them.
Is Snefru secure?
It has a broken past. Early versions were cryptanalysed by Eli Biham and Adi Shamir, and Merkle strengthened the design by adding passes in response. Given that history and how little it has been studied since, do not use Snefru for anything security-critical.
Why is my Snefru hash always 64 characters?
The variant available here outputs 256 bits, and each hex character represents 4 bits, so the result is exactly 64 characters no matter how much text you hash.
Is my text sent anywhere?
Your text is sent to our server to be hashed, because browsers cannot compute Snefru — they only expose the SHA family. It is hashed and immediately discarded, never logged and never stored.