Using a WhatsApp conversation as evidence: what a PDF can and can't show

What chatinprint gives you

chatinprint turns a WhatsApp export into a PDF on your own device. In a dispute, four parts of it matter more than the chat bubbles.

The cover page. Every PDF starts with a page that describes the copy itself:

• the participants, and the time of the first and the last message;
• how many messages are shown out of how many the export holds (“N of M messages shown”);
• every filter you used, such as a date range, chosen participants or hidden system messages;
• the layout, Chat or Transcript;
• the source file’s name, size and SHA-256 fingerprint;
• when the PDF was generated, and the chatinprint version that made it;
• a note that times are the phone’s local time and that no time zone is recorded.

The Transcript layout. Instead of chat bubbles, a table: every message numbered, the date exactly as the export wrote it next to a standard ISO date, the time, the author, the message, and any attachment with a short form of its fingerprint.

The evidence appendix. A table of every media file the chat refers to: its name, type and size, its SHA-256 fingerprint when the file is present, and whether it was included in the export or missing.

The manifest. A JSON file and a plain-text version with the same fingerprints for the export and for every media file, the message counts, the filters, the tool version and the time it was generated.

Nothing in it is edited: message text is kept exactly as WhatsApp exported it; filtering is allowed and always disclosed.

What the SHA-256 fingerprints show — and what they don’t

A SHA-256 fingerprint is a 64-character value calculated from the exact bytes of a file.

chatinprint computes a SHA-256 fingerprint of every file you choose and of every media file in the export, from the original bytes, on your device. The cover page, the evidence appendix and the manifest record these 64-character values. Anyone can recompute them later with free tools, such as shasum on macOS and Linux or certutil on Windows, and compare: if the values match, the file has not changed since it was fingerprinted. A fingerprint says nothing about who wrote a message, whether the export is complete, or when the fingerprint was made.

They show that a file you have today is bit-for-bit the same as the file chatinprint fingerprinted. Change one character and the fingerprint changes completely. Anyone can recompute it with free tools.

They don’t show:

• who wrote a message;
• that the export contains the whole conversation: WhatsApp limits one export to reported: 10,000 recent messages with media and reported: 40,000 without, according to several sources, and a phone can only export the messages it still has;
• that the phone’s clock was right: times are the phone’s local wall-clock time, and the export records no time zone;
• when the fingerprint was made: the “generated” time comes from your own device’s clock, so it is not a trusted timestamp;
• that nothing was changed before the export;
• who the participants are: names appear as the exporting phone displayed them.

A fingerprint checks a file, not a story. That is what makes it useful: anyone can confirm that a copy hasn’t changed since you made it, without having to trust you or chatinprint.

How to check a fingerprint yourself

You don’t need chatinprint to check a fingerprint. Every computer has a free tool for it built in.

1. 1

   Open a terminal in the folder that holds the file: Terminal on macOS or Linux, Command Prompt or PowerShell on Windows.

2. 2

   Run the command for your system

   On macOS or Linux:

   shasum -a 256 "Conversa do WhatsApp com Osvaldo Tavares.zip"

   On Windows, in Command Prompt:

   certutil -hashfile "Conversa do WhatsApp com Osvaldo Tavares.zip" SHA256

   On Windows, in PowerShell:

   Get-FileHash -Algorithm SHA256 "Conversa do WhatsApp com Osvaldo Tavares.zip"

3. 3

   Compare the 64 characters it prints with the value on the cover page or in the manifest. Upper or lower case doesn’t matter: some tools print capitals.

Use your own file name in place of the example, and keep the quotes if the name has spaces. The text version of the manifest repeats all three commands, and the README.txt inside the HTML archive repeats the first two, so the instructions travel with the files.

Keep the originals

A PDF is a copy. The originals are what everyone can go back to.

• Keep the phone, and keep the chat in WhatsApp. Don’t delete the conversation after exporting it.
• Keep the original export, the ZIP or the .txt file, exactly as WhatsApp saved it. Don’t open the text file in an editor and save it again, and don’t rename or re-zip anything: any change, even an invisible one, gives the file a different fingerprint.
• Store copies in two places, such as a computer and an external drive.
• Keep the PDF, the manifest and the original export together, so anyone can check one against the others.
• If photos, voice notes or documents matter, export with media. An export without media keeps only a mention of each file in the text, so its content can’t be shown or checked later.

Say what you left out

You can narrow a PDF to what matters: a date range, some of the participants, no system messages, or no embedded media. chatinprint never hides that. Every filter is printed on the cover page, and “N of M messages shown” makes a partial copy visible at a glance.

A filtered copy can still be useful: a chat that runs for years may hold one relevant week, and an excerpt keeps unrelated private messages, yours or other people’s, out of a dispute.

Expect to be asked for the rest. The other side, or whoever decides the matter, may want the full export to check that nothing around the excerpt changes its meaning. With the original kept, you can produce the whole chat at any time, and the source fingerprint on its cover will match the one on your excerpt.

Rules differ by country

How a printed chat or an electronic file can be used depends on where you are and on the case. This page names no statute, article or procedure; our pages for other markets add notes for those countries, written to be reviewed by a local lawyer.

Brazil

In Brazil, the formal route to authenticate digital content is an ata notarial drawn up by a notary (tabelião), who records facts they personally verify. Our PDF does not replace it.

explains what an ata notarial is and how a PDF can accompany it.

Spain and the rest of the EU

In Spain and the rest of the EU, qualified timestamp and eIDAS certification services exist. chatinprint is not one of them.

covers the same ground for Spain.

Mexico and Latin America

How courts there treat printed chats and electronic files is a question for a local lawyer; our page in Spanish lists what to ask.

Turkey

How courts there treat printed chats and electronic files is a question for a local lawyer; our page in Turkish lists what to ask.

Indonesia

How courts there treat printed chats and electronic files is a question for a local lawyer; our page in Indonesian lists what to ask.

Egypt and Saudi Arabia

How courts there treat printed chats and electronic files is a question for a local lawyer; our page in Arabic lists what to ask.

Questions to ask your lawyer

Take the PDF, the manifest and the original export with you, and ask:

• Which format does the court or authority expect: printout, PDF, the original export file, or the phone itself?
• Do I need a notary, a certified expert or a trust service to authenticate it?
• Should I include photos and voice notes, and in what form?
• Is a filtered excerpt acceptable, or should I provide the full chat?
• How should I store the original phone and export?