PDF Digital Signatures — Types, Legality, and How They Work

Types of PDF Signatures

Electronic Signature (e-Sign)

A typed name, drawn signature, or uploaded signature image placed on a PDF. Legally valid for most business transactions under the IT Act 2000.

Digital Signature (DSC)

A cryptographic signature that proves the signer's identity using a Digital Signature Certificate (DSC) issued by a licensed Certifying Authority. Required for certain government and legal documents.

Aadhaar eSign

An Aadhaar-based electronic signature available to all Indian residents. OTP-verified through UIDAI.

Legal Validity in India

Under the Information Technology Act, 2000 (amended):

• Electronic signatures are legally valid for most documents
• Digital signatures (DSC) are required for specific filings (MCA, Income Tax, GST)
• Aadhaar eSign has the same legal validity as electronic signatures

Documents That Require DSC

• Company incorporation (MCA)
• Income tax returns for companies
• GST returns
• Patent and trademark filings
• Government tender bids

Documents Where e-Sign Is Sufficient

• Business contracts
• Employment agreements
• NDAs
• Invoices and purchase orders
• Internal approvals

Adding Signatures to PDFs

Simple Image Signature

1. Sign on white paper
2. Photograph and crop the signature
3. Use the spec resizer to get exact dimensions
4. Overlay on the PDF

Drawing a Signature

Some PDF tools let you draw a signature with your mouse or touchscreen and place it on the document.

Security Considerations

• Simple image signatures can be copied and forged
• Digital signatures (DSC) are cryptographically secure and tamper-evident
• For sensitive documents, always use DSC or Aadhaar eSign
• Password-protect the signed PDF to prevent signature removal