How do you check that an exported text message PDF has not changed? SHA-256 on a Mac

By Kayabyte · Last updated 11 November 2026

Short answer: an export from Exhibitly includes a file called SHA256SUMS.txt that lists a SHA-256 fingerprint for every exported file. To check a folder, open Terminal, go to the folder and run shasum -a 256 -c SHA256SUMS.txt. Each file prints OK if it is exactly the file that was exported, and FAILED if even one byte differs. A matching fingerprint shows the file has not changed since the export. It does not show that the messages were genuine in the first place. This is general information, not legal advice; ask your lawyer or court what they want to receive.

Why anyone checks

When you hand over a PDF of text messages, the other side, a lawyer or a court clerk may ask whether it is the same file that came off the phone. A fingerprint is a way to answer that. It is a long string of letters and numbers worked out from the contents of a file. Change a single character in the file and the string changes completely. If you write the fingerprints down when you export, and the same strings come out later, the file has not been edited or damaged in between.

What the fingerprints do and do not prove

They show: a file is still byte for byte what it was when it was exported. That includes the PDF, the Excel file and each original attachment.
They do not show: that the messages on the phone were real, that nobody edited a conversation before it was exported, or that a court will accept the file. Courts decide what they accept.
WhatsApp export files: a WhatsApp export is a text file, and edits made to it before it is imported cannot be detected. Exhibitly records the SHA-256 of the file when it reads it, which fixes what was read, not whether it was edited earlier.

Check an Exhibitly export in Terminal

We tried these steps on the sample export on our website on 11 November 2026, on a Mac running macOS 27.2.

Keep the whole export folder together. SHA256SUMS.txt sits next to the PDF, the Excel file and the Attachments folder, and its lines use paths relative to that folder.
Open Terminal.
Type cd (with a space), drag the export folder from Finder into the Terminal window, and press Return.
Run:

shasum -a 256 -c SHA256SUMS.txt

Every line should end in OK. A line ending in FAILED means that file differs from the exported one. A line saying the file could not be read usually means it was moved, renamed or left out of the folder.

To see one file’s fingerprint on its own, run shasum -a 256 "name of file.pdf" and compare the string with the same file’s line in SHA256SUMS.txt.

Good habits

Check once straight after export, so you know the folder was complete when you saved it.
Keep an untouched copy of the whole folder somewhere else, such as an external drive, and do your sharing from a copy.
Send the folder, not just the PDF, if the person receiving it wants to check. Without SHA256SUMS.txt they have nothing to compare against.
Don’t edit files in the folder. Even opening a file and saving it again in another program can change its bytes and with it the fingerprint. If you need a marked-up version, make a copy and name it clearly.
Keep the phone and the iPhone backup it came from. The fingerprints describe the export, and the phone is the source.

Where Exhibitly helps

Exhibitly is a Mac app we make. It reads an iPhone backup made in Finder (encrypted backups too, with your own backup password), the Messages app on your Mac, or a WhatsApp chat export, and writes a numbered PDF, an Excel file with one row per message and the original attachments with SHA-256 fingerprints. SHA256SUMS.txt covers every exported file, and a verification page in the export says which source was read. It works offline and nothing is uploaded. You can look at a sample export and run the check above on it before you pay anything.

What it cannot do: it cannot recover deleted messages, it does not read Android SMS or Android backups (only WhatsApp export files), and it does not prove that messages are genuine or decide whether a court will accept them.

Steps with Exhibitly

Make an iPhone backup in Finder: see how to make an iPhone backup on a Mac.
Open Exhibitly and pick the conversation. Choose the whole thread, a date range or excerpts with context.
Export, then open the export folder and look for SHA256SUMS.txt next to the PDF and Excel file.
Run the Terminal check above and keep the folder untouched.

The free preview has every feature but exports only the first 15 messages and marks the PDF “PREVIEW, NOT FOR FILING”. Personal is USD 39 once; Evidence Bundle (Bates numbers, exhibit cover page, merging iPhone and Mac) is USD 69 once. macOS 15 or later.

Download Exhibitly (free preview)

Questions

Is SHA-256 the same as a digital signature? No. A fingerprint lets anyone holding the list check that a file is unchanged. A signature ties a file to a person or a certificate. Exhibitly writes fingerprints, not signatures.

What if one file says FAILED? Don’t use that file. Get the file again from your untouched copy, or export again from the phone or backup, and check the new folder.

Can I check the PDF on a different computer? Anyone with a tool that works out SHA-256 can compare the string. The steps above are for a Mac.

Does a matching fingerprint make the PDF admissible? No. Courts decide what they accept, and may want the phone itself. Ask a lawyer.