eIDAS Signature Framework

The EDK provides an eIDAS-compliant digital signature framework for creating, validating, and timestamping electronic signatures that meet EU regulatory requirements.

Overview

The eIDAS signature framework provides:

• Multiple signature formats - CAdES (binary), PAdES (PDF), JAdES (JSON), XAdES (XML)
• ETSI compliance - Baseline levels B, T, LT, and LTA per EN 319 102-1
• Document sovereignty - Two-step signing keeps documents on-premise while using remote keys
• Timestamping - RFC 3161 TSA integration
• Signature validation - Certificate revocation and trust list checking
• Multi-platform - Core API runs on JVM and JavaScript
• REST Client - Call remote eIDAS servers using the same SignatureProvider interface

Architecture

Signature Formats

Format	Use Case	Standards
CAdES	Binary data, attachments	EN 319 122
PAdES	PDF documents with visible signatures	EN 319 142
JAdES	JSON data, APIs	TS 119 182
XAdES	XML documents	EN 319 132

Signature Levels

Each format supports ETSI baseline levels:

Level	Description	Use Case
B	Basic signature	Short-term validity
T	With timestamp	Proves signing time
LT	Long-term validation	Certificate revocation data embedded
LTA	Long-term archival	Periodic timestamp renewal

EDK vs VDX

The eIDAS functionality is split between EDK (client libraries) and VDX (server deployment):

Component	Location	Description
Signature Client	EDK	Core signing commands with DI integration
DSS Provider	EDK	Local in-process signing using EU DSS library
REST Client	EDK	HTTP client implementing SignatureProvider
REST API Models	EDK	OpenAPI-generated DTOs for REST communication
REST Server	VDX	Full REST server with persistence (PostgreSQL, MySQL, SQLite)

This separation enables:

• Mobile apps: Use REST client to delegate signing to a server
• Desktop apps: Use DSS provider for local in-process signing
• Hybrid: Create digest locally, sign remotely, complete locally

Modules

Module	Description	Platform
lib-eidas-signature-client-public	Public API interfaces	Multiplatform
lib-eidas-signature-client-impl	Implementation with IDK integration	Multiplatform
lib-eidas-signature-client-dss	Local DSS provider for full eIDAS compliance	JVM only
lib-eidas-signature-rest-api	OpenAPI models for REST endpoints	Multiplatform
lib-eidas-signature-rest-client	REST client implementing SignatureProvider	JVM

REST Server in VDX

The eIDAS REST Server with database persistence is part of VDX. See VDX eIDAS Server for deployment documentation.

Quick Start

Sign a PDF Document

import com.sphereon.eidas.signature.*
import kotlin.time.Duration.Companion.hours

// Inject the signing command
val signDocumentCommand: SignDocumentCommand

// Prepare the document
val pdfBytes = File("contract.pdf").readBytes()
val input = SignInput.pdf(pdfBytes)

// Configure signature parameters
val params = PAdESParameters(
    signatureLevel = SignatureLevel.PAdES_BASELINE_LT,
    visualSignatureParameters = VisualSignatureParameters(
        fieldParameters = SignatureFieldParameters(
            page = 1,
            originX = 50f,
            originY = 700f,
            width = 200f,
            height = 50f
        ),
        textParameters = SignatureTextParameters(
            text = "Signed by: John Doe\nDate: 2025-01-02"
        )
    ),
    reason = "Contract approval",
    location = "Amsterdam, Netherlands"
)

// Sign the document
val result = signDocumentCommand.execute(
    SignDocumentArgs(
        input = input,
        keyInfo = keyManagerService.getKeyInfo("signing-key"),
        signatureLevel = SignatureLevel.PAdES_BASELINE_LT,
        parameters = params,
        timestampParameters = TimestampParameters(
            tsaUrl = "http://timestamp.example.com/rfc3161"
        )
    ),
    sessionContext
)

when (result) {
    is Ok -> {
        val signed = result.value
        File("contract-signed.pdf").writeBytes(signed.signedData)
        println("Signed at: ${signed.signingTime}")
        println("Certificate: ${signed.certificateInfo?.subjectDN}")
    }
    is Err -> println("Error: ${result.error.message}")
}

Validate a Signature

val validationResult = validateSignatureCommand.execute(
    ValidateSignatureArgs(
        signedDocument = signedPdfBytes,
        checkCertificateRevocation = true
    ),
    sessionContext
)

when (validationResult) {
    is Ok -> {
        val validation = validationResult.value
        println("Valid: ${validation.isValid}")

        validation.signatures.forEach { sig ->
            println("Signature: ${sig.signatureId}")
            println("  Status: ${sig.indication}")
            println("  Signer: ${sig.certificateInfo?.subjectDN}")
            println("  Time: ${sig.signingTime}")
        }
    }
    is Err -> println("Validation error: ${result.error.message}")
}

Two-Step Signing for Document Sovereignty

The two-step signing workflow is designed for scenarios where documents must not leave your infrastructure. This is critical for:

• Regulatory compliance - Documents containing sensitive data (healthcare, financial, legal) that cannot be transmitted to external signing services
• Data sovereignty - Organizations that must keep documents within specific geographic or network boundaries
• Air-gapped environments - Secure facilities where documents cannot reach the internet
• HSM/smartcard integration - Using remote or hardware-based keys while keeping documents local

How It Works

1. Step 1 (Local): Create a cryptographic digest (hash) of the document. Only this small hash value leaves your system.
2. Step 2 (Remote): Send the hash to your signing service (HSM, cloud KMS, smartcard) which returns a signature value.
3. Step 3 (Local): Combine the signature with the original document to produce the signed output.

The document never leaves your infrastructure. Only a hash (typically 32-64 bytes) is transmitted externally.

Implementation

// Step 1: Create digest locally - document stays on-premise
val digestResult = createDigestCommand.execute(
    CreateDigestArgs(
        input = SignInput.pdf(pdfBytes),
        keyInfo = certificateChain,  // Public cert only
        parameters = PAdESParameters(signatureLevel = SignatureLevel.PAdES_BASELINE_LT)
    ),
    sessionContext
)

val digest = digestResult.getOrThrow()
// Only the hash is sent externally - document remains local
println("Hash to sign: ${digest.digestToSign.toBase64()}")  // ~32-64 bytes

// Step 2: Send ONLY the hash to signing service (HSM, cloud KMS, smartcard)
// The signing service never sees the document content
val signatureValue = signingService.signHash(digest.digestToSign)

// Step 3: Complete signature locally - combine signature with document
val signedResult = completeSignatureCommand.execute(
    CompleteSignatureArgs(
        signingSessionId = digest.signingSessionId,
        signatureValue = signatureValue,
        signatureDocumentBytes = digest.signatureDocumentBytes
    ),
    sessionContext
)

// Final signed document - created entirely within your infrastructure
val signedDoc = signedResult.getOrThrow()
File("document-signed.pdf").writeBytes(signedDoc.signedData)

Use Cases

Scenario	Benefit
Healthcare records	Patient data never leaves hospital network
Financial documents	Contracts stay within bank infrastructure
Government classified	Documents remain in secure facility
GDPR compliance	Personal data doesn't cross jurisdictions
Legal discovery	Maintain chain of custody for evidence

Configuration

eidas:
  signature:
    default-level: PAdES_BASELINE_B
    default-digest-algorithm: SHA256

    timestamp:
      enabled: true
      url: http://timestamp.example.com/rfc3161
      policy-oid: 1.2.3.4.5
      digest-algorithm: SHA256
      timeout-ms: 30000

    validation:
      check-revocation: true
      revocation-freshness: 86400
      allow-expired-certificates: false
      lotl-url: https://ec.europa.eu/tools-databases/lotl/eu-lotl.xml

    cache:
      enabled: true
      ttl-seconds: 3600
      max-size: 1000

Next Steps

• Client API - Detailed client API documentation with format-specific parameters
• REST Server - Deploy signature services as REST APIs