What happens when a document is tampered
Even a single edited number breaks the proof
Starting from the proofed employment letter, someone changed John Doe's base salary from 200,000 CAD to 250,000 CAD after it was signed — everything else on the page, including the embedded checksum ID, was left untouched.
1. The tampered document
The checksum ID is still stamped on the page, so it still looks like a proofed document at a glance — but the bytes no longer match what was originally signed.
2. Verification fails
When this file is uploaded on the verify page, Checksum recomputes the fingerprint, finds the embedded ID in the registry, but the recomputed checksum no longer matches the original — so verification is rejected.
Does not match
A record was found, but the bytes differ — the document may have been altered.
File
JohnDoe-employment letter-proofed.pdf