Nutrient Java SDK

Add digital signatures to PDFs in Java

Visible and invisible digital signatures with PKCS#12 certificates
PAdES-T-compliant timestamps for long-term validation and regulatory compliance
Customizable signature appearance — auto-generated text, custom images, or styled typography
Electronic signatures (visual only) for internal approvals without cryptographic validation

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DIGITAL SIGNATURES IN JAVA

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import io.nutrient.sdk.signing.PdfSigner;
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import io.nutrient.sdk.signing.DigitalSignatureOptions;
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import io.nutrient.sdk.signing.SignatureAppearance;
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try (PdfSigner signer = new PdfSigner()) {
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    DigitalSignatureOptions options =
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        new DigitalSignatureOptions();
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    options.setCertificatePath("certificate.pfx");
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    options.setCertificatePassword("password");
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    options.setSignerName("John Doe");
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    options.setReason("Final Approval");
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    options.setLocation("New York");
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    SignatureAppearance appearance =
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        new SignatureAppearance();
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    appearance.setUseAutoGeneratedText(true);
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    appearance.setShowValidationMark(true);
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    signer.signField(
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        "input.pdf", "output_signed.pdf",
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        "ApprovalSignature", options, appearance
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    );
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}

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import io.nutrient.sdk.signing.PdfSigner;
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import io.nutrient.sdk.signing.DigitalSignatureOptions;
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try (PdfSigner signer = new PdfSigner()) {
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    DigitalSignatureOptions options =
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        new DigitalSignatureOptions();
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    options.setCertificatePath("certificate.pfx");
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    options.setCertificatePassword("password");
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    options.setSignerName("John Doe");
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    options.setReason("Document Approval");
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    options.setLocation("New York");
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    options.setContactInfo("john@example.com");
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    signer.sign(
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        "input.pdf",
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        "output_signed_invisible.pdf",
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        options
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    );
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}

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import io.nutrient.sdk.signing.PdfSigner;
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import io.nutrient.sdk.signing.DigitalSignatureOptions;
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import io.nutrient.sdk.signing.TimestampConfiguration;
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try (PdfSigner signer = new PdfSigner()) {
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    DigitalSignatureOptions options =
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        new DigitalSignatureOptions();
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    options.setCertificatePath("certificate.pfx");
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    options.setCertificatePassword("password");
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    options.setSignerName("Legal Department");
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    options.setReason("Contract Execution");
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    // Add a trusted timestamp for PAdES-T compliance.
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    TimestampConfiguration timestamp =
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        new TimestampConfiguration();
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    timestamp.setServerUrl(
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        "http://timestamp.digicert.com"
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    );
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    options.setTimestamp(timestamp);
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    signer.sign(
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        "input.pdf",
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        "output_signed_timestamped.pdf",
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        options
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    );
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}

USE CASES

When developers reach for this SDK

Automate contract signing workflows

Contracts, NDAs, and agreements need to be signed at scale. The SDK signs PDFs programmatically in Spring Boot services, batch jobs, or API endpoints — no manual signing step.

Meet regulatory compliance requirements

eIDAS, FDA 21 CFR Part 11, and other frameworks require cryptographic signatures with timestamps. Add PAdES-T compliant signatures with trusted TSA timestamps for long-term validation.

Guarantee document integrity

Signed documents must be tamper-proof. The SDK embeds a certificate chain and encrypted hash — any modification after signing triggers tamper warnings in PDF viewers.

Brand your signature experience

Signatures need to match corporate guidelines. Customize appearance with company logos, handwritten signature images, branded fonts, colors, and custom text.

Digital signature capabilities for Java

Visible digital signatures

Sign PDFs with a visible signature field that shows signer name, date, reason, and a validation mark. Customize with images, text, or auto-generated content.

VIEW GUIDE

Auto-generated text from signer metadata
Custom images: handwritten signatures or logos
Styled typography: font, size, and color control

Invisible digital signatures

Sign PDFs without any visual change. The signature embeds a certificate chain and encrypted hash into the PDF structure for tamper detection.

VIEW GUIDE

Document looks unchanged after signing
Verifiable in any PDF viewer’s signature panel
One method call: signer.sign()

Advanced signature workflows

PAdES-T timestamps, SHA-512 hashing, and electronic signatures. Meet eIDAS, FDA, and FIPS compliance requirements.

VIEW GUIDE

PAdES-T: Trusted timestamps via RFC 3161 TSA
SHA-512 for high-security environments
Electronic signatures (visual only, no certificate)

Signature types

visible invisible PAdES-T SHA-512 electronic PKCS#12

ADVANCED CAPABILITIES

Beyond basic PDF signing

The SDK handles more than one-off signatures. Build signing into automated pipelines, add trusted timestamps for compliance, and deploy anywhere Java runs.

EXPLORE JAVA SDK

Illustration of digital signature workflows on a PDF document

Long-term validation with timestamps

PAdES-T signatures include a trusted timestamp from an RFC 3161 TSA. The signature remains valid even after the certificate expires — required for legal archival.

Batch signing at scale

Sign hundreds of documents in a loop or with Java’s concurrency tools. Each signing follows the same pattern: Configure options and call sign() or signField().

Tamper detection built in

Every signed PDF includes an encrypted hash. If the document is modified after signing, PDF viewers display tamper warnings automatically.

Server-side signing

No GUI dependencies — sign PDFs in Spring Boot services, background jobs, or API handlers. Deploy on Linux, Docker, and CI/CD pipelines.

Frequently asked questions

How do I add a digital signature to a PDF in Java?

Create a PdfSigner instance, configure DigitalSignatureOptions with your PKCS#12 certificate path and password, set signer metadata (name, reason, location), and call signer.sign() for invisible signatures or signer.signField() for visible signatures. See the visible signature guide for a complete working example.

What is the difference between visible and invisible digital signatures?

Both embed a certificate chain and encrypted hash for tamper detection. Visible signatures also render a signature appearance on the page — showing signer name, date, and an optional image or validation mark. Invisible signatures leave the document visually unchanged while still being verifiable through a PDF viewer’s signature panel.

How do I sign a PDF with a PKCS#12 certificate in Java?

Set the certificate path and password on DigitalSignatureOptions using setCertificatePath() and setCertificatePassword(). The SDK handles PKCS#12 parsing, private key extraction, hash computation, and signature embedding automatically. Both .pfx and .p12 files are supported.

How do I add a trusted timestamp for PAdES-T compliance?

Create a TimestampConfiguration, call setServerUrl() with your TSA endpoint (e.g. DigiCert’s public timestamp service), and set it on the signature options with setTimestamp(). The SDK communicates with the TSA via the RFC 3161 protocol automatically. See the advanced signatures guide.

Does the SDK support SHA-512 for stronger security?

Yes. Call options.setHashAlgorithm(SignatureHashAlgorithm.SHA512) to use a 512-bit hash instead of the default SHA-256. This provides stronger collision resistance for high-security environments, government compliance (FIPS 140-2), and organizational policies requiring stronger cryptographic algorithms.

Can I add an electronic signature without a certificate?

Yes. Pass null for the options parameter when calling signField(), and provide only a SignatureAppearance with an image path. The SDK renders the image as a flattened graphic on the page without cryptographic validation. This is suitable for internal approvals and acknowledgment workflows. See the electronic signatures section.

Can I customize the visible signature appearance?

Yes. SignatureAppearance supports auto-generated text (signer name, date, location, reason), custom images (JPEG, PNG — handwritten signatures or logos), custom text content, and full typography control with setFontName(), setFontSize(), and setTextColor(). You can also show a validation checkmark with setShowValidationMark(true).

Can I sign PDFs in batch in a server-side Java application?

Yes. The SDK has no GUI dependencies — sign PDFs in Spring Boot services, batch jobs, or API handlers. Iterate through documents in a loop, configure options once, and call sign() or signField() for each file. Deploy on Linux, Docker, and any environment where Java runs.

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