Digital Signatures

Sign documents with cryptographic digital signatures.

Digital vs. Electronic Signatures

Digital signatures provide:

• Authentication: Verifies signer identity
• Integrity: Detects document changes
• Non-repudiation: Signer cannot deny signing

Signing a Document

With Certificate

1. Open the document
2. Click a signature field (or Sign → Sign Document)
3. Select your digital certificate
4. Enter certificate password
5. Configure appearance
6. Click Sign

Creating Certificates

If you don’t have a certificate:

1. Click Sign → Manage Certificates
2. Click Create Self-Signed Certificate
3. Enter your information
4. Set validity period
5. Create the certificate

Signature Appearance

Customize how your signature looks:

Graphic

• Draw your signature
• Upload signature image
• Use certificate icon

Text

• Name
• Date
• Location
• Reason for signing

Standard Text

Include standard information:

• Distinguished name
• Date and time
• Certificate issuer

Verifying Signatures

Automatic Verification

When opening a signed PDF:

1. Penvio checks all signatures
2. Status shown for each:
   • ✅ Valid
   • ⚠️ Warning
   • ❌ Invalid

Manual Verification

1. Click on the signature
2. View Signature Properties
3. Check:
   • Signer identity
   • Certificate validity
   • Document integrity

Signature States

Valid

• Certificate is trusted
• Document unchanged since signing
• Signature is cryptographically correct

Invalid

• Document modified after signing
• Certificate revoked or expired
• Cryptographic verification failed

Unknown

• Certificate not trusted
• Cannot verify certificate chain
• Add certificate to trusted list to resolve

Timestamp Signatures

Add trusted timestamps:

1. Configure timestamp server
2. Sign the document
3. Timestamp proves when signed
4. Valid even after certificate expires

LTV (Long-Term Validation)

Ensure signatures remain valid long-term:

1. Embed certificate chain
2. Embed revocation information
3. Add trusted timestamp
4. Signature verifiable indefinitely

Best Practices

• Use certificates from trusted CAs for legal docs
• Include timestamps for important documents
• Keep private keys secure
• Back up certificates
• Use LTV for archival documents

Next Steps

• Certificate Encryption - Use PKI certificates for document encryption
• Password Protection - Add password protection alongside signatures
• PDF Standards - Ensure signed documents meet archival standards