How does PDF SignCheck verify a PDF digital signature?

PDF SignCheck cryptographically validates the digital signatures embedded in PDF documents. It checks that the document has not been tampered with after signing, verifies the signer's certificate chain against trusted root Certificate Authorities (CAs), and outputs a stamped PDF with a "Verified ✓" badge — similar to clicking "Trust this certificate" in Adobe Acrobat.

Is my PDF document stored or saved during digital signature verification?

No. Your file is processed entirely in memory on the server. It is never written to disk, never stored in any database, and is discarded immediately after the verified PDF is returned to your browser. We take privacy seriously — your documents remain yours.

What types of PDF digital signatures and certificates are supported?

PDF SignCheck supports PDFs that contain PKCS#7 / CMS digital signatures — the standard used by government portals, official certificate authorities, and digital signing platforms. This includes documents from DigiLocker, e-District, MCA, UIDAI, and similar government services worldwide.

Why does Adobe Acrobat Reader display a PDF signature as "Not Verified"?

Adobe Acrobat only trusts certificates from its own Adobe Approved Trust List (AATL). Many government and institutional signers are not on that list. Our tool auto-trusts the signer's certificate after cryptographic verification — exactly what Adobe asks you to do manually when you click "Trust this certificate." The downloaded verified PDF includes a visual stamp so it's clear the signature has been validated.

Is the online PDF signature verification process cryptographically secure?

Yes. We perform full PKCS#7 signature verification: we extract the signed hash from the signature, independently compute the hash of the document's byte ranges, and compare them. We also validate the certificate chain up to a trusted root CA from the Mozilla CA trust store. This is the same process that Adobe Acrobat and other professional PDF tools use.

Are there daily or rate limits for PDF cryptographic verification?

To prevent abuse, we rate-limit to 10 requests per minute per IP address. The maximum file size is 50 MB. These limits are sufficient for normal usage. If you need higher throughput for enterprise use, please contact us.

Which Indian government certificates and portals are supported?

PDF SignCheck fully supports digital signature verification for official Indian government certificates. This includes UIDAI Aadhaar Cards, state e-District certificates (such as Caste, Income, Domicile, and Birth/Death certificates), DigiLocker-issued PDF documents, NFSA Ration Cards, Income Tax / PAN documents, and any official PDF signed via CCA India (Controller of Certifying Authorities) root credentials.

How do I resolve the "Signature Not Verified" or "Signature Not Checked" warning on Aadhaar or Caste certificates?

Simply upload your signed PDF to PDF SignCheck. Our system extracts the digital signature, cryptographically validates the hash integrity against trusted root certificates, and generates a stamped PDF. When you download this verified document, the signature will show as valid, making it suitable for direct submission.

Legal Agreements

Terms of Service

Last updated: May 31, 2026

1. How do you accept these terms?

By accessing or using the PDF SignCheck website, verification API, or related checking utilities (collectively, the "Service"), you agree to be bound by these Terms of Service ("Terms"). If you do not agree to these Terms, you may not access or use the Service.

2. What services does PDF SignCheck provide?

PDF SignCheck provides online cryptographic validation and certificate inspection utilities for digitally signed PDF documents.

Our signature verification engine parses documents conforming to the ISO 32000-1 and ISO 32000-2 (PDF 2.0) specifications. The system programmatically checks PKCS#7 / CMS (Cryptographic Message Syntax) signatures as defined in RFC 5652, validates certificate chains up to 10 hierarchical levels deep against global Trusted Lists (including the EUTL and CCA India), and returns a verified PDF stamped incrementally using standard PDF incremental saves.

3. What is our policy on user content and file uploads?

Document Inspection: You retain full copyright and ownership of any files uploaded to PDF SignCheck. We do not claim ownership over your files.
In-Memory Processing: We do not store, duplicate, or maintain your files on non-volatile media. Uploaded documents are read into volatile server RAM buffers, analyzed in memory for cryptographic signature validity, and immediately garbage-collected within a maximum window of 1,200 seconds (20 minutes). No hard-drive swap space or persistent object storage is utilized.
Prohibited Files: You must not upload any malicious files, viruses, scripts, or documents designed to harm or compromise the Service infrastructure.

4. How do subscriptions, accounts, and payments work?

Plan Tiers: Daily usage limit thresholds are defined per account tier over a rolling 24-hour cycle (Guest: 2 checks/day, Free registered: 5 checks/day). A Top-up Credits Pack grants exactly 100 additional credits.
Credits Expiration: Purchased Top-up Credits remain valid for exactly 12 months (365 days) from the date of purchase.
Payments and Billing: Billing and transaction processing is managed securely via our merchant checkout partner, Dodo Payments.
Refunds: Since our services provide instant digital certificate validation tools and digital downloads, refund policies are managed on a case-by-case basis through Dodo Payments.

5. What are the rate limits and fair usage rules?

To prevent automated scraping, bot attacks, and infrastructure degradation, we implement a strict global rate limit of exactly 10 verification requests per rolling 60-second window per IP address. File size limits are capped at exactly 52,428,800 bytes (50 MB) per document upload. Bypassing these boundaries programmatically may lead to temporary or permanent IP ban restrictions.

PDF SignCheck processes verification checks programmatically in real-time. In accordance with fair usage rules, individual document size limits are capped at 50 MB per upload, and API clients are rate-limited to 10 requests per minute per IP address to ensure 99.9% platform availability.

6. What are the disclaimers and limitations of liability?

THE SERVICE IS PROVIDED "AS IS" AND "AS AVAILABLE" WITHOUT ANY EXPRESS OR IMPLIED WARRANTIES. PDF SIGNCHECK DOES NOT WARRANT THAT THE cryptographic checking engine or certificate chains validated represent legal evidence in any specific jurisdiction. Signature validation is provided as a technological inspection tool. We are not responsible for any document signing decisions, business losses, or legal outcomes resulting from signature checking reports.

7. How can you contact us regarding these terms?

Questions or reports of terms violations can be sent to: hi@pdfsigncheck.com