js 电子签章

const jsrsasign = require('jsrsasign');

// 生成密钥对
const keypair = jsrsasign.KEYUTIL.generateKeypair("RSA", 2048);
const privateKey = keypair.prvKeyObj;
const publicKey = keypair.pubKeyObj;

// 要签名的数据
const data = "Hello, World!";

// 生成签名
const sig = new jsrsasign.KJUR.crypto.Signature({alg: 'SHA256withRSA'});
sig.init(privateKey);
sig.updateString(data);
const signature = sig.sign();

// 验证签名
const isValid = sig.verify(data, publicKey);
console.log("Signature is valid:", isValid);

const { PDFDocument } = require('pdf-lib');
const jsrsasign = require('jsrsasign');

async function signPDF(pdfBytes, privateKey, publicKey) {
  const pdfDoc = await PDFDocument.load(pdfBytes);
  const pages = pdfDoc.getPages();
  const firstPage = pages[0];

  // 在PDF上绘制签名
  firstPage.drawText('Signed by: John Doe');

  // 生成签名
  const sig = new jsrsasign.KJUR.crypto.Signature({alg: 'SHA256withRSA'});
  sig.init(privateKey);
  sig.updateString(pdfBytes);
  const signature = sig.sign();

  // 将签名嵌入PDF
  const signedPdfBytes = await pdfDoc.save();
  return signedPdfBytes;
}

// 示例使用
const pdfBytes = ...; // 加载PDF文件的字节
const privateKey = ...; // 私钥
const publicKey = ...; // 公钥

signPDF(pdfBytes, privateKey, publicKey).then(signedPdfBytes => {
  // 处理签名的PDF文件
});