Calculate checksum
Calculate the SHA-256 of a file and check whether a download is complete and unchanged.
Paste the value from the download page – the file name before or after is fine.
In your account, directly with your SafeDoc files: Calculate the checksum of your SafeDoc files and store it next to them as a .sha256 file.
What it is good for
Many providers of software, drivers or operating systems publish a SHA-256 checksum next to the download. If you compare it with the checksum of your file, you know that nothing broke during the download and nobody swapped the file on the way.
- Choose the file – it stays on your device.
- Paste the value from the download page into the comparison field.
- The tool tells you whether both match.
Frequently asked questions
What is a checksum?
A short fingerprint of a file. If even one byte changes, a completely different value comes out. If the value matches the one from the provider, the file arrived complete and unchanged.
Is my file uploaded?
No. The browser reads the file locally and calculates with its built-in Web Crypto API. Neither the file nor the checksum is sent or stored.
Why SHA-256 and not MD5?
SHA-256 is the usual standard for downloads today. With MD5 and SHA-1, two different files with the same value can be produced deliberately – they are no longer suitable for checking authenticity. That is why the Web Crypto API does not offer MD5 at all.
How large can the file be?
Up to 2 GB. The browser has to load the file into memory in full for the calculation; older devices give up with larger files.
Does a matching checksum prove the file is safe?
It proves that you have exactly the file the provider published. It does not say whether that file itself can be trusted. So take the comparison value from the provider’s official page.
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