What is SHA-256 used forIt makes a short fingerprint of data, used to check that a file has not changed

TimeBinder adds a layer of protection against AI and human fraud and disputes.

The file stays on your device. Your browser makes a digital fingerprint of the file. TimeBinder records the fingerprint and the time, not the file.

Short answer

SHA-256 is a cryptographic hash function that turns any data into a fixed 64-character fingerprint. It is used to check that a file has not changed, and in digital signatures, certificates, software downloads and Bitcoin. The same input always gives the same fingerprint, and the data cannot be recovered from it.

What it does

SHA-256 is part of the SHA-2 family, specified by NIST in FIPS 180-4. It takes data of any size and produces a 256-bit value, normally written as 64 hexadecimal characters. Change one byte of the input and the output changes completely.

That makes it useful for checking downloads against a published value, verifying that a file matches an earlier copy, signing documents and securing blockchains. See what is a file hash for the basic idea.

How it is used in a TimeBind

A TimeBind records a SHA-256 fingerprint of the exact file and a time, anchored to Bitcoin. The fingerprint is made in your browser and the file is not uploaded. Anyone with the same file can recompute the fingerprint and compare it with the recorded one. Try it yourself with the SHA-256 file hash checker.

A matching fingerprint shows the file is identical. It does not show who made the file, whether its content is true or who owns it.

Make a TimeBind: first one free →

First Pooled TimeBind free, no card, then from US$5. An ASAP TimeBind is US$15.

Frequently asked questions

Can SHA-256 be reversed?

No practical way is known to recover the original data from the hash. Short or guessable inputs can still be guessed by trying candidates.

Is SHA-256 encryption?

No. Hashing is one-way and has no key to unlock it. Encryption is two-way and uses a key.

Is SHA-256 secure?

It is widely used and no practical collision attack is publicly known. Security advice can change, so check current guidance for important uses.

Does a hash show who made a file?

No. It only identifies the exact contents of the file.

Sources

NIST, FIPS 180-4, Secure Hash Standard.
TimeBinder, SHA-256 file hash checker.

Related guides and tools

Your file’s fingerprint, anchored to a global network secured by real electricity and cryptography.

Editing a file—including with AI—changes its fingerprint, not its existing network record.

How this works

Your file’s SHA-256 fingerprint, a short code worked out from its exact contents, is made in your browser, and the file itself stays on your device. A cryptographic commitment to that fingerprint, which may be combined with others, is then anchored in a block on the Bitcoin blockchain. Bitcoin is secured by proof of work: computers around the world spend real electricity to add each block, and changing an earlier block would mean redoing that work faster than the rest of the network. Until that block is confirmed, your proof is pending. Once the Bitcoin anchoring is confirmed, you can verify the proof against that recorded commitment. The confirmed record can then be checked; Pooled TimeBinds are checked through TimeBinder, while ASAP TimeBinds can also be checked independently. If you check the file later and its fingerprint still matches, that shows the file existed no later than the recorded time. The record doesn’t show who made the file, whether AI was used, or that its contents are true.

Your filestays on your device
FingerprintSHA-256
Network timestampon Bitcoin

Record a fingerprint of the file you rely on

Add a layer of protection against AI and human fraud and disputes: a dated, checkable record of the exact file you hold.

Open the app and sign in with email or Google.
Add your files. They stay on your computer.
Seal them and download your Proof of Time certificates.

Open TimeBinder →

First Pooled TimeBind free, no card, then from US$5. See pricing.