PDF Authenticity Checker
Verify digital signatures and cryptographic integrity instantly.100% Local Execution via WebAssembly.
Upload PDF to Authenticate
Drag & drop any signed or unsigned PDF
Zero Knowledge
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Signature Validation
Checks PKCS#7 structures
Revision History
Detects post-signing edits
Visualization of Incremental Updates
How PDF Validation Works
A digital signature isn't just an image of a handwritten signature. It's a cryptographic seal that uses math to prove two things:
- 1
Identity
Proves the document came from the holder of a specific certificate (e.g., a company or government).
- 2
Integrity
Ensures not a single pixel or letter has changed since the exact moment it was signed.
The "Incremental Update" loophole
PDFs are designed to be editable. When you "save" a PDF, you are often appending changes to the end of the file rather than rewriting it. Malicious actors can sometimes take a validly signed document and append invisible changes (like hiding paragraphs) without breaking the original signature structure technically, even though the visual meaning changes.
Contracts & Agreements
Verify that the vendor agreement you received hasn't been subtly altered after your legal team approved the draft.
Government Forms
Authenticate digitally issued certificates, tax documents, or ID proofs to ensure they aren't counterfeits.
Academic Transcripts
Universities issue cryptographically signed result sheets. Validation ensures a student hasn't modified their GPA.