PDFSigner

The PDFSigner package allows adding digital signatures and image stamps to PDF files. It uses libraries like pdfcpu and pdfsign to manipulate and sign PDFs.

Features

• Add image stamps to PDFs.
• Normalize PDFs to ensure compatibility.
• Digitally sign PDFs using PFX certificates.

Installation

Make sure you have Go installed on your machine. To install the package and its dependencies, run:

go get github.com/digitorus/pdfsign
go get github.com/pdfcpu/pdfcpu
go get software.sslmate.com/src/go-pkcs12

Clone the repository or copy the code into your project.

Usage Example

Below is an example of how to use the package to sign a PDF:

package main

import (
    "log"
    "os"

    "github.com/alexsetta/pdfsigner"
)

func main() {
    config := pdfsigner.Config{
        PFXPath:     "./files/certificate.pfx",
        Password:    os.Getenv("PFX_PASSWORD"), // Use environment variable for the password
        ImgPath:     "./files/stamp.png",
        Debug:       true,
        Name:        "Your Name",
        Location:    "Your Location",
        Reason:      "Reason for Signing",
        ContactInfo: "youremail@example.com",
    }

    err := pdfsigner.Sign("./files/input.pdf", "./files/signed_output.pdf", config)
    if err != nil {
        log.Fatalf("Error signing PDF: %v", err)
    }

    log.Println("PDF signed successfully!")
}

Configuration

The Config structure is used to configure the signing process:

• PFXPath: Path to the PFX file containing the digital certificate.
• Password: Password for the PFX file (it is recommended to use an environment variable, such as PFX_PASSWORD).
• ImgPath: Path to the stamp image (optional).
• Debug: Flag to enable debug logs.
• Name: Signer's name.
• Location: Signing location.
• Reason: Reason for signing.
• ContactInfo: Signer's contact information.

Main Methods

Sign

Digitally signs a PDF. Parameters:

• inPdf: Path to the input PDF file.
• outPdf: Path to the output PDF file.
• conf: Configuration of type Config.

addImageSignature

Adds an image stamp to the PDF. Parameters:

• inPdf: Path to the input PDF file.
• outPdf: Path to the output PDF file.
• imgPath: Path to the stamp image.

normalizePDF

Normalizes the PDF to ensure compatibility. Parameters:

• inFile: Path to the input PDF file.
• outFile: Path to the output PDF file.

Tests

The package includes a test file PDFSigner_test.go to validate the signing functionality. Make sure to configure the input and output files correctly in the ./files/ directory.

To run the tests, use the command:

go test ./...

Requirements

• Go 1.18 or higher.
• Digital certificate in PFX format.
• Image for the stamp.
• Environment variable PFX_PASSWORD configured with the certificate password.

Directory Structure

• ./files/: Directory to store input files, output files, certificates, and images.

License

This project is licensed under the terms of the MIT license.