How to Check a Hash Value, Using certutil, shasum and Get-FileHash
How to calculate a file's SHA-256 yourself and compare it with a recorded value. If you prefer to do it in the browser, you can also use the hash checker.
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How do I calculate it on Windows?
Type the following at the Command Prompt.
`` certutil -hashfile filename SHA256 ``
Microsoft Learn's certutil page lists the form hashfile InFile [HashAlgorithm] (opened and checked). In PowerShell you can also use Get-FileHash filename -Algorithm SHA256 (-Algorithm checked on the Microsoft Learn Get-FileHash page, checked 2026-10-29).
How do I calculate it on Mac or Linux?
Type the following in a terminal.
`` shasum -a 256 filename ``
On Linux, sha256sum filename is also used. We checked sha256sum on the man7.org man page, and shasum on a copy of the man page on ss64.com (not an official Apple page) (checked 2026-10-29).
How do I compare the result?
Check whether the 64-character value printed matches the recorded value. Ignore differences in upper and lower case and the spaces that certutil inserts. If even one character differs, it is a different file.
What does a match tell me?
If the values match, the file can be considered unchanged since it was recorded. It does not show that nothing was deleted or altered before the export, or that the conversation is authentic.
What about the PDF's own hash?
A PDF's own hash cannot be placed inside the PDF, so it is supplied in a separate .sha256.txt file. Note that opening the PDF and saving it again changes the value.
What if I rename the file?
If the content is the same, the value does not change.
Privacy
Reading the file, building the PDF and calculating hashes all happen in your browser. No chat or attachment is uploaded and there is no account. See the privacy policy and the disclaimer.
Related guides
- What a hash value does and does not tell you
- Hash checker
- Keeping LINE chats as evidence
- Saving LINE chats on iPhone and Android
Sources (checked 2026-10-29)
- Microsoft Learn certutil: https://learn.microsoft.com/en-us/windows-server/administration/windows-commands/certutil (opened and checked. hashfile InFile [HashAlgorithm])
- Microsoft Learn Get-FileHash: https://learn.microsoft.com/en-us/powershell/module/microsoft.powershell.utility/get-filehash (opened and checked)
- sha256sum(1): https://man7.org/linux/man-pages/man1/sha256sum.1.html (opened and checked)
- shasum: https://ss64.com/mac/shasum.html (copy of the man page. Opened and checked)
Ready to try it?
Drop your exported .txt file on the convokeep app for a free preview. The first 3 pages are free (watermarked, no integrity page); saving the full PDF is a one-time paid feature. No chat or attachment is uploaded: the file is read in your browser. To check later that a file is unchanged, use the hash checker.
This document was generated locally in the user's browser; no content was uploaded.