There are several things that you can inspect to authenticate the integrity of a note. We recommend doing this prior to obtaining Bitcoin Cash Notes from any third parties.
1. Inspect the note for any general irregularities that may indicate tampering or counterfeiting. Using a lamp and magnifying glass, look at every part over the note for any signs of cutting, drawing, printing or any other blemishes or irregularities. Hold the note in front of the lamp to see through the paper for any irregularities. Also check for an alterations from the original by comparing the note with another of the same version number. You can access the designs for each released version at our changelog.
2. Ensure that the note id printed on the note corresponds to the version number also printed on the note. You can verify this by visiting the changelog and ensuring the the note id falls within the range associated with the note version.
3. Validate the QR Code and Bitcoin Cash address is valid by scanning the QR code which will reveal the Bitcoin Cash address. You can conveniently use a mobile wallet such as the Electron Cash Mobile Wallet for scanning QR Codes. This will provide a high level of confidence that the QR Code and the Bitcoin Cash address have not been altered.
4. Verify that the 4 digit code printed on the top left-hand corner of the tamper-evident seal equals the last 4 digits of the Bitcoin Cash address.
5. Very closely inspect in and around the tamper-evident seal for any signs of tampering – a magnifying glass and bright lamp may assist. This may include among other things cuts, abrasions, peeling, increased thickness, visible defects on the seal or the word VOID or part of it on the seal. Pay extra special attention to inspect for any evidence of tampering around the perimeter of the seal, both on the seal and paper portion. Check the other side of the note directly opposite the seal to see if the key has been accessed from the back. Carefully shine a bright torch through the tamper seal (never directly into your eye) and look at it through the other side of the note, normally there will be a region in the center that is completely opaque. Please note that on rare occasion there are manufacturing blemishes present on the tamper seal, however they will always be only very minor.