OneNote file signature
Magic number at the start of the file
A OneNote section file begins with a fixed 16-byte GUID, {7B5C52E4-D88C-4DA7-AEB1-5378D02996D3} stored in its little-endian byte order. Microsoft's MS-ONESTORE specification defines it as the file-type GUID of the .one revision store.
What this magic number means
A magic number is a short, fixed run of bytes at a known position that tells a program what a file really is, no matter what the filename says. If a file starts with the bytes E4 52 5C 7B 8C D8 A7 4D AE B1 53 78 D0 29 96 D3, it is a OneNote file.
GUID signatures like this one read differently from how they are written: the first three groups are little-endian, which is why the file starts E4 52 5C 7B rather than 7B 5C 52 E4.
Formats that use the E4 52 5C 7B signature
These file types in our database carry this signature:
How to check a file's signature
You can read the first bytes of any file yourself. The magic bytes are shown in hex, the same way this page lists them.
Linux & macOS
- xxd -l 16 example.one
- hexdump -C -n 16 example.one
- file example.one
Windows (PowerShell)
- Format-Hex -Path example.one -Count 16
Python
- open("example.one","rb").read(16).hex()
In your browser
- Drop the file into the WhatFileType identifier, which reads the signature without uploading it.
Frequently asked questions
What is the OneNote file signature?
OneNote files start with the hex bytes E4 52 5C 7B 8C D8 A7 4D AE B1 53 78 D0 29 96 D3. This magic number identifies the format regardless of the file's name or extension.
How do I check a file's magic number?
Open the file in a hex editor, or run a command such as xxd -l 16 example.one on Linux or macOS, or Format-Hex -Path example.one -Count 16 in Windows PowerShell, and read the first bytes.
Can a file fake the OneNote signature?
Renaming a file does not change its bytes, so the extension can lie but the signature usually cannot. A genuine OneNote file has these exact bytes; a file with the wrong bytes is not really OneNote, whatever its name says.