1. Project Overview

OpenSign Electronic Signature Tool Edition

OpenSign Electronic Signature / Electronic Contract Open-Source Tool Edition, including frontend and backend source code. Its main features include digital certificate generation, handwritten signatures, seal generation, document signing, locating signing positions by keywords, and positioning signatures by dragging. The source code allows you to understand the frontend and backend technologies behind electronic signature and electronic contract products on the market, making it easier to build your own electronic signature or electronic contract system.

The core technologies and tools for electronic signatures have been open-sourced. The open-source edition adopts the more permissive MIT open-source license and is not subject to commercial restrictions. Product features include electronic seal creation, handwritten signature generation, digital certificate generation, PDF-to-image conversion, electronic signing (keyword-based signing and designated-position signing), and document signature verification.

2. Open Source License

Licensed under MIT

3. Screenshots

Utility Library Overview

Handwritten Signature Panel

• Provides a frontend page for personal handwritten signatures and generates handwritten signature images.

Electronic Seal Creation

• Generate electronic seals for enterprises. There are two ways to create seals:
  System Generation: Generate electronic seal images based on surrounding seal text and horizontally arranged text.

• Seal Impression Generation: Stamp a seal on white paper, take a photo or scan and upload it, then crop the seal impression image. Automatically remove the background from the cropped image to generate a transparent seal.

Digital Certificate Generation (Generated Using Public-Key Cryptography, Not a CA Digital Certificate)

• Generate digital certificates for testing electronic signatures. These certificates are generated using public-key cryptography and are primarily intended to help developers complete the electronic signing workflow. They are not issued by a CA and have no legal validity!

• The following is a brief introduction to SSL certificates and CA certificates in terms of their functions and uses:

• SSL certificates and CA certificates are both digital certificates, but they have significant differences in their functions and purposes.

• A CA certificate is issued by an authoritative Certificate Authority (CA). During the electronic signature process, a CA digital certificate can verify the identity of the signer and use encryption to associate the signature data with the public key contained in the digital certificate, ensuring the security and reliability of the signature. At the same time, a CA certificate can ensure that the signed document has not been tampered with, guaranteeing the integrity, confidentiality, and non-repudiation of electronic information. By using a CA digital certificate, the identity of the signing party can be verified, ensuring that the signature complies with legal requirements and is tamper-proof, thereby giving electronic contracts the same legal validity as paper contracts. Before signing an electronic contract, users must complete real-name authentication, after which the CA issues a digital certificate to verify the identity of the signing party. Therefore, CA digital certificates play a critical role in electronic signatures by ensuring the legality and security of the signing process and giving electronically signed documents a higher level of credibility and legal validity.

• An SSL certificate is a security protocol used to protect the security of data transmission between websites and users. SSL certificates use public-key encryption technology to encrypt and transmit users' sensitive information (such as credit card numbers and passwords), preventing malicious third parties from intercepting or stealing it. At the same time, SSL certificates can verify a website's identity, ensuring that users are communicating with the correct website. Therefore, SSL certificates are primarily used to encrypt data transmission between websites and users, protecting user privacy and security.

Convert PDF Files to Images

• Provides tools for converting PDF files into images.

• The electronic signature process involves operations such as previewing documents to be signed, specifying signature positions, and signing documents on web pages. Since images offer better browser compatibility and usability than PDF files, PDF documents are generally converted into images before being displayed to users during web-based electronic signing. Once users specify the signature position on the page and complete the signing process, the backend service calculates the positions and dimensions of the electronic seal or handwritten signature, along with the PDF file dimensions, and applies the signature at the exact position in the PDF document.

Electronic Document Signing

• Electronic document signing refers to the process of applying electronic signatures to electronic documents.

• OpenSign - Open Source Edition provides two methods of electronic signing, as follows:
  Keyword-Based Signing: Specify the keywords in the PDF document where signatures need to be applied. During signing, the system searches the document for the corresponding keywords and applies an electronic seal or handwritten signature at their locations to complete the electronic signing process.

• Position-Based Signing: Directly specify the positions in the PDF document where an electronic seal or handwritten signature should be applied. During signing, the electronic signature is applied directly at the specified positions.

Signed Document Verification

• Verifies whether an electronic document has been tampered with, as well as the electronic seals or handwritten signatures and digital certificate information contained in the document.

• Verification generally involves the following scenarios:

• The PDF file contains no digital signature, meaning that it has never been electronically signed and therefore requires no verification.

• The PDF file contains a digital certificate, but an error occurs during signature verification. The signature contains incorrect, unrecognized, corrupted, or suspicious data, indicating that the signature information has been tampered with. Verification fails.

• The PDF file contains a digital certificate, and all digital certificates are recognizable, but the document has been tampered with. Verification fails.

• The PDF file contains a digital certificate, and the document has not been tampered with. Verification succeeds.

4. Feature Overview

OpenSign Electronic Signature / Electronic Contract Open-Source Tool Edition, including frontend and backend source code. Its main features include digital certificate generation, handwritten signatures, seal generation, document signing, locating signing positions by keywords, and positioning signatures by dragging. The source code allows you to understand the frontend and backend technologies behind electronic signature and electronic contract products on the market, making it easier to build your own electronic signature or electronic contract system.

5. Tech Stack

Backend

Build Setup

# Navigate to the project directory
cd open-sign

# Build the package
mvn clean package

# Run the JAR package
java -jar target/opensign-demo.jar

Code Structure

- open-sign       OpenSign Tool
    - controller    Provides demonstration API endpoints
    - enums         Common enumeration classes
    - service       Signing services
        - cert        Certificate services
        - image       Seal image processing and PDF-to-image conversion
        - pdf         Signature position calculation and PDF document signing
        - verify      PDF signature verification
    - utils         Utility classes

Frontend

Build Setup

Recommended Node.js version: v16.x

# Navigate to the project directory
cd open-sign-vue

# Install dependencies
npm install -registry=https://registry.npm.taobao.org

# Before starting, launch the backend service and modify the proxy address in vite.config.js. Otherwise, the signing functionality will not be available.
# Start the service at localhost:8080
npm run dev

# Build for production
npm run build