Verify PDF Digital Signatures Online.
Instantly check the authenticity and validity of any digital signature embedded in a PDF document. Ensure your files haven't been tampered with since they were signed.
Drag & drop your signed PDF here
or click to browse · Max 20MB
How Signature Verification Works
Validate the integrity of your signed PDFs without any software installation.
Upload PDF
Upload the PDF document you want to verify. We process the file securely inside your browser's memory, ensuring total privacy.
Cryptographic Analysis
Our tool analyzes the document's ByteRange to verify that the file has not been modified or tampered with since the signature was applied.
Review Signer Data
View detailed information about the signer, the Certificate Authority (CA) that issued the DSC, and the exact timestamps of the signatures.
Zero Data Stored. Total Privacy Guaranteed.
Your files are processed in-memory and immediately discarded after extraction. No data is logged, no cookies track you, and no file ever touches permanent storage. Your sensitive documents remain yours — always.
What Is PDF Digital Signature Verification?
Digital signature verification is the process of mathematically confirming that a PDF document is exactly as it was when it was originally signed, and that the signature came from an identified and trusted source. Unlike a scanned handwritten signature — which can be easily forged by copying an image — a digital signature is created using Public Key Infrastructure (PKI) cryptography and cannot be faked or transferred from one document to another.
When someone signs a PDF, their signing software calculates a unique cryptographic hash (a fingerprint) of the entire document at that exact moment. This hash is then encrypted using the signer's private key and embedded inside the PDF along with their public X.509 certificate. To verify the signature, our tool reverses this process: it decrypts the embedded hash using the signer's public key and re-calculates the current document's hash. If both hashes match, the document is authentic and unaltered.
This is the same technology used by banks, courts, and government agencies worldwide to validate electronic documents. Under India's Information Technology Act, 2000, a valid digital signature on an electronic document carries the same legal weight as a handwritten signature on a physical document.
When Should You Verify a PDF Digital Signature?
- Before accepting a contract or agreement: If you receive a signed PDF contract, verifying the signature confirms that the document was not modified after the other party signed it.
- Validating GST or MCA filings: Government-signed acknowledgements from GSTN, MCA21, or income tax portals carry digital signatures. Verifying them ensures the document is an authentic government record.
- Checking DigiLocker documents: Certificates and marksheets issued via DigiLocker are digitally signed by government bodies. Verification confirms their authenticity for use in applications.
- Legal and compliance audits: Auditors and lawyers often need to verify the integrity of signed documents as part of due diligence, ensuring no clause was altered post-signature.
- Real estate and property documents: Registered sale deeds and property documents signed with DSCs require verification before any transfer of title or mortgage application.
How Our Signature Verifier Works Under the Hood
Our verification engine is built on the PDF specification's digital signature standard (ISO 32000). Here is what happens in the seconds between you clicking verify and seeing your result:
- ByteRange Parsing: The tool reads the PDF's
/ByteRangeentry — a pair of byte offsets that define exactly which portions of the file were covered by the signature when it was created. These two ranges together represent the entire document, excluding only the signature value bytes themselves. - Hash Recalculation: The tool reads all bytes within those ranges and computes a SHA-256 (or SHA-1, depending on the DSC standard) cryptographic hash of the data.
- PKCS#7 Decryption: The embedded signature bytes (stored in the PDF's
/Contentsentry) contain a PKCS#7/CMS SignedData structure. The tool extracts the encrypted hash and the signer's public key certificate from this structure. - Comparison: The decrypted hash is compared to the recalculated hash. A match means the document is intact. A mismatch means the document was altered after signing.
- Certificate Chain Check: The tool also reads the issuing Certificate Authority (CA) from the certificate to confirm the signer's identity was verified by a licensed authority like eMudhra, NSDL, or Sify.
Frequently Asked Questions
How do I know if a signature is valid?
Our tool parses the PDF to ensure that the cryptographic hash matches the original document state at the time of signing. If the document was altered afterward, the signature is rendered invalid, and you will not see intact signer properties.
What does it mean if a document has been tampered with?
If someone edits a PDF after it has been digitally signed (e.g., changing text or amounts), the cryptographic seal breaks. This indicates the file is no longer in its authentic, original state.
Can I verify multiple signatures at once?
Yes. If a PDF has been signed by multiple individuals (such as a multi-party contract), our engine detects all embedded signatures and lists the verification details for each one.
What is the difference between a valid and an authentic signature?
A valid signature confirms the document has not been altered since it was signed. An authentic signature additionally confirms that the signer's identity was verified by a trusted Certificate Authority (CA) before the certificate was issued. Our tool checks both: document integrity via hash comparison, and identity via certificate issuer information.
Does this tool work for Aadhaar-signed and DigiLocker PDFs?
Yes. PDFs signed via Aadhaar eSign or downloaded from DigiLocker (such as marksheets, caste certificates, or driving licences) are signed using standard X.509 digital signatures issued by the NSDL or NIC Certificate Authority. Our tool reads and verifies these signatures exactly like a DSC-signed business document.
What if the verification result shows "signature invalid"?
An invalid result means that the document's content was altered after the signature was applied. This could be due to intentional tampering, but can also be caused by certain PDF editors or printers that slightly reformat the file. If you suspect tampering, do not accept the document and request a fresh, freshly signed copy from the sender.
Is my PDF uploaded to your servers during verification?
Your PDF is transmitted over an encrypted HTTPS connection to our server solely for processing. It is read into memory, analyzed, and the result is returned to your browser. The file is never written to disk and is permanently purged from memory as soon as the response is sent. We do not log, store, or retain any part of your document.
Can I verify a PDF signed with a foreign certificate (outside India)?
Yes. Our tool supports any PDF that follows the ISO 32000 digital signature standard, regardless of which country's Certificate Authority issued the signing certificate. It works with certificates from EU-based eIDAS providers, US-based DigiCert or Sectigo, and any other internationally recognized CA.