Create a REST API for PDF digital signatures with webhooks

Overview An automation workflow that creates a complete REST API for digitally signing PDF documents using n8n webhooks. This service demonstrates how to implement secure document signing functionality through standardized API endpoints with file upload and download capabilities.

Use Case This workflow is designed for developers and automation specialists who need to implement digital document signing. It's particularly useful for: - Integrating PDF signing capabilities into existing document workflows - API-based automation of signature processes - Creating proof-of-concept implementations for document verification systems - Learning n8n's webhook capabilities and file handling techniques - Testing PDF signing in development environments before production implementation

What This Workflow Does

API-Based Document Management - Exposes RESTful webhook endpoints for all document operations - Handles multipart/form-data uploads for PDF documents - Processes JSON payloads for signing configuration - Provides download functionality for completed documents

Digital Certificate Handling - Uploads existing PFX/PKCS12 digital certificates - Generates new certificates with customizable attributes - Securely manages certificate storage and access - Associates certificates with signing operations

Cryptographic PDF Signing - Applies digital signatures using industry-standard cryptographic methods - Embeds signature information within PDF document structure - Validates document integrity through cryptographic verification - Preserves original document while adding signature elements

Webhook Integration System - Routes different API methods to appropriate handlers - Validates request payloads and file content - Manages authentication through webhook paths - Returns structured responses for integration with other systems

Technical Architecture