ZgaPdfSigner

A javascript tool to sign a pdf or set protection of a pdf in web browser.
And it is more powerful when used in Google Apps Script or nodejs.

PS: ZGA is the abbreviation of my father's name.
And I use this name to hope the merits from this application will be dedicated to my parents.

Main features

Sign a pdf with an invisible pkcs#7 signature.
Sign a pdf with a visible pkcs#7 signature by drawing an image.
Sign a pdf and set DocMDP.
Add a new signature to a pdf if it has been signed already. (An incremental update)
Add a document timestamp from TSA. ( 🚫Not available in web browser)
Sign a pdf with a timestamp from TSA. ( 🚫Not available in web browser)
Enable signature's LTV. ( 🚫Not available in web browser)
Set password protection to a pdf. Supported algorithms:
- 40bit RC4 Encryption
- 128bit RC4 Encryption
- 128bit AES Encryption
- 256bit AES Encryption
Set public-key certificate protection to a pdf. Supported algorithms are as same as the password protection.

About signing with TSA and LTV

Because of the CORS security restrictions in web browser, signing with a timestamp from TSA or enabling LTV can only be used in Google Apps Script or nodejs.

The Dependencies

How to use this tool

❓ For more details please see the wiki.

Web Browser

Just import the dependencies and this tool.

<script src="https://unpkg.com/[email protected]/dist/pdf-lib.min.js" type="text/javascript"></script>
<script src="https://unpkg.com/[email protected]/dist/forge.min.js" type="text/javascript"></script>
<script src="https://cdn.jsdelivr.net/npm/zgapdfsigner/dist/zgapdfsigner.min.js" type="text/javascript"></script>

Google Apps Script

Load the dependencies and this tool.

// Simulate setTimeout function for pdf-lib
function setTimeout(func, sleep){
  Utilities.sleep(sleep);
  func();
}
// Simulate window for node-forge
var window = globalThis;
// Load pdf-lib
eval(UrlFetchApp.fetch("https://unpkg.com/[email protected]/dist/pdf-lib.min.js").getContentText());
// Load node-forge
eval(UrlFetchApp.fetch("https://unpkg.com/[email protected]/dist/forge.min.js").getContentText());
// Load ZgaPdfSigner
eval(UrlFetchApp.fetch("https://cdn.jsdelivr.net/npm/zgapdfsigner/dist/zgapdfsigner.min.js").getContentText());

Or simply import the library of ZgaPdfToolkit

Add the library of ZgaPdfToolkit to your project, and suppose the id of library you defined is "pdfkit".
Script id: 1T0UPf50gGp2fJ4dR1rZfEFgKYC5VpCwUVooCRNySiL7klvIUVsFBCZ9m
Load the library.

pdfkit.loadZga(globalThis);

nodejs

Install

npm install zgapdfsigner

Import

const Zga = require("zgapdfsigner");

Let's sign

Sign with an invisible signature.

/**
 * @param {ArrayBuffer} pdf
 * @param {ArrayBuffer} cert
 * @param {string} pwd
 * @return {Promise<Blob>}
 */
async function sign1(pdf, cert, pwd){
  /** @type {SignOption} */
  var sopt = {
    p12cert: cert,
    pwd: pwd,
    permission: 1,
  };
  var signer = new Zga.PdfSigner(sopt);
  var u8arr = await signer.sign(pdf);
  return new Blob([u8arr], {"type" : "application/pdf"});
}

Sign with a visible signature of an image.

/**
 * @param {ArrayBuffer} pdf
 * @param {ArrayBuffer} cert
 * @param {string} pwd
 * @param {ArrayBuffer} imgdat
 * @param {string} imgtyp
 * @return {Promise<Blob>}
 */
async function sign2(pdf, cert, pwd, imgdat, imgtyp){
  /** @type {SignOption} */
  var sopt = {
    p12cert: cert,
    pwd: pwd,
    drawinf: {
      area: {
        x: 25,  // left
        y: 150, // top
        w: 60,  // width
        h: 60,  // height
      },
      imgData: imgdat,
      imgType: imgtyp,
    },
  };
  var signer = new Zga.PdfSigner(sopt);
  var u8arr = await signer.sign(pdf);
  return new Blob([u8arr], {"type" : "application/pdf"});
}

Sign with a visible signature of drawing a text.

//TODO

Use it in Google Apps Script

/**
 * @param {string} pwd Passphrase of certificate
 * @return {Promise}
 */
async function createPdf(pwd){
  // Load pdf, certificate
  var pdfBlob = DriveApp.getFilesByName("_test.pdf").next().getBlob();
  var certBlob = DriveApp.getFilesByName("_test.pfx").next().getBlob();
  // Sign the pdf
  /** @type {SignOption} */
  var sopt = {
    p12cert: certBlob.getBytes(),
    pwd,
    signdate: "1",
    ltv: 1,
  };
  var signer = new Zga.PdfSigner(sopt);
  var u8arr = await signer.sign(pdfBlob.getBytes());
  // Save the result pdf to some folder
  var fld = DriveApp.getFolderById("a folder's id");
  fld.createFile(Utilities.newBlob(u8arr, "application/pdf").setName("signed_test.pdf"));
}

Use queryPassword function in ZgaPdfToolkit.

function myfunction(){
  var spd = SpreadsheetApp.getActiveSpreadsheet();
  pdfkit.queryPassword("createPdf", "Please input the passphrase", spd.getName());
}

Use it in nodejs

const m_fs = require("fs");
const m_path = require("path");
async function main(){
  /** @type {string} */
  var pdfPath = m_path.join(__dirname, "_test.pdf");
  /** @type {string} */
  var pfxPath = m_path.join(__dirname, "_test.pfx");
  /** @type {string} */
  var ps = "";
  /** @type {string} */
  var imgPath = m_path.join(__dirname, "_test.png");

  if(process.argv.length > 3){
    pfxPath = process.argv[2];
    ps = process.argv[3];
  }else if(process.argv[2]){
    ps = process.argv[2];
  }

  if(!ps){
    // throw new Error("The passphrase is not specified.");
    pfxPath = "";
  }

  /** @type {Buffer} */
  var pdf = m_fs.readFileSync(pdfPath);
  /** @type {Buffer} */
  var pfx = null;
  if(pfxPath){
    pfx = m_fs.readFileSync(pfxPath);
  }
  /** @type {Buffer} */
  var img = null;
  /** @type {string} */
  var imgType = "";
  if(imgPath){
    img = m_fs.readFileSync(imgPath);
    imgType = m_path.extname(imgPath).slice(1);
  }

  /** @type {SignOption} */
  var sopt = {
    p12cert: pfx,
    pwd: ps,
    permission: pfx ? 2 : 0,
    signdate: "1",
    reason: "I have a test reason.",
    location: "I am on the earth.",
    contact: "[email protected]",
    ltv: 1,
    debug: true,
  };
  if(img){
    sopt.drawinf = {
      area: {
        x: 25, // left
        y: 150, // top
        w: 60,
        h: 60,
      },
      imgData: img,
      imgType: imgType,
    };
  }

  /** @type {Zga.PdfSigner} */
  var ser = new Zga.PdfSigner(sopt);
  /** @type {Uint8Array} */
  var u8dat = await ser.sign(pdf);

  if(u8dat){
    /** @type {string} */
    var outPath = m_path.join(__dirname, "test_signed.pdf");
    m_fs.writeFileSync(outPath, u8dat);
    console.log("Output file: " + outPath);
  }

  console.log("Done");
}

Let's protect the pdf

Set password protection to the pdf.

/**
 * @param {ArrayBuffer} pdf
 * @param {string} upwd
 * @param {string} opwd
 * @return {Promise<Blob>}
 */
async function protect1(pdf, upwd, opwd){
  /** @type {EncryptOption} */
  var eopt = {
    mode: Zga.Crypto.Mode.RC4_40,
    permissions: ["modify", "annot-forms", "fill-forms", "extract", "assemble"],
    userpwd: upwd,
    ownerpwd: opwd,
  };
  var cyptor = new Zga.PdfCryptor(eopt);
  var pdfdoc = await cyptor.encryptPdf(pdf);
  u8arr = await pdfdoc.save({"useObjectStreams": false});
  return new Blob([u8arr], {"type" : "application/pdf"});
}

Set public-key certificate protection to the pdf.

/**
 * @param {ArrayBuffer} pdf
 * @param {ArrayBuffer} cert
 * @return {Promise<Blob>}
 */
async function protect2(pdf, cert){
  /** @type {EncryptOption} */
  var eopt = {
    mode: Zga.Crypto.Mode.AES_128,
    pubkeys: [{
      c: cert,
      p: ["copy", "modify", "copy-extract", "annot-forms", "fill-forms", "extract", "assemble"],
    }],
  };
  var cyptor = new Zga.PdfCryptor(eopt);
  var pdfdoc = await cyptor.encryptPdf(pdf);
  u8arr = await pdfdoc.save({"useObjectStreams": false});
  return new Blob([u8arr], {"type" : "application/pdf"});
}

Sign and set protection.

/**
 * @param {ArrayBuffer} pdf
 * @param {ArrayBuffer} cert
 * @param {string} pwd
 * @param {string} opwd
 * @return {Promise<Blob>}
 */
async function signAndProtect1(pdf, cert, pwd, opwd){
  /** @type {SignOption} */
  var sopt = {
    p12cert: cert,
    pwd: pwd,
  };
  /** @type {EncryptOption} */
  var eopt = {
    mode: Zga.Crypto.Mode.RC4_128,
    permissions: ["modify", "annot-forms", "fill-forms", "extract", "assemble"],
    ownerpwd: opwd,
  };
  var signer = new Zga.PdfSigner(sopt);
  var u8arr = await signer.sign(pdf, eopt);
  return new Blob([u8arr], {"type" : "application/pdf"});
}

Sign and set protection by the same certificate.

/**
 * @param {ArrayBuffer} pdf
 * @param {ArrayBuffer} cert
 * @param {string} pwd
 * @return {Promise<Blob>}
 */
async function signAndProtect2(pdf, cert, pwd){
  /** @type {SignOption} */
  var sopt = {
    p12cert: cert,
    pwd: pwd,
  };
  /** @type {EncryptOption} */
  var eopt = {
    mode: Zga.Crypto.Mode.AES_256,
    permissions: ["modify", "annot-forms", "fill-forms", "extract", "assemble"],
    pubkeys: [],
  };
  var signer = new Zga.PdfSigner(sopt);
  var u8arr = await signer.sign(pdf, eopt);
  return new Blob([u8arr], {"type" : "application/pdf"});
}

Thanks

The module of setting protection was almost migrated from TCPDF.

License

This tool is available under the MIT license.

zboris12 / zgapdfsigner Goto Github PK

zgapdfsigner's Introduction

ZgaPdfSigner

Main features

About signing with TSA and LTV

The Dependencies

How to use this tool

Web Browser

Let's sign

Let's protect the pdf

Thanks

License

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