Implementing Qualified Electronic Signature (QES) on Your Website

Clients often complain: "Our EDI system doesn't work with QES in the browser." The problem is typical — an outdated approach via ActiveX or NPAPI plugins that are unsupported by modern browsers. We've solved it dozens of times. How to integrate QES according to Federal Law 63-FZ without headache — we break it down practically.

QES is the only type of electronic signature equivalent to a handwritten signature. According to the Ministry of Digital Development, over 70% of Russian companies already use QES in corporate document flow, tax reporting, or real estate transactions. Certified cryptographic tools (CSP) like CryptoPro CSP or VipNet CSP and a qualified certificate from an accredited certification authority are mandatory components of a legally valid signature. Without QES, it is impossible to submit reports to Rosreestr or sign a contract with a counterparty. Typical implementation time is 14 days, and transaction cost savings reach 40%. This article is a practical integration experience, from choosing an architecture to deployment.

How to Choose a QES Integration Method: Plugin or Cloud?

Two main approaches: installing CryptoPro Browser Plugin on each computer or cloud QES via DSS. Let's compare them.

What to Do If the Browser Doesn't Support ActiveX?

Modern browsers (Chrome, Edge, Yandex) block NPAPI plugins. The only reliable solution is cloud QES via DSS or CryptoPro CSP Web (Chromium support via Chrome Extension). In practice, we recommend cloud QES as a future-proof option. It does not require CSP installation on the user's PC and works on any device.

Why Cloud QES Is Replacing Plugins?

According to our data, over the last period more than 80% of new projects choose cloud QES. The reasons are obvious: no need to maintain outdated technologies, users sign documents from any device. We have implemented CryptoPro DSS on 6 projects — no failures in half a year. Moreover, cloud QES is implemented 2 times faster than plugin-based and reduces support costs by 40% due to the absence of CSP installation on each computer.

Technical Stack

CryptoPro CSP is the most common CSP in Russia. It is installed on the user's computer. For browser operation, CryptoPro EDS Browser Plugin (NPAPI/COM component) or CryptoPro CSP Web is used.

Alternatives:

• Rutoken EDS — token with built-in GOST cryptography, Rutoken Web plugin
• VipNet CSP — alternative CSP
• CryptoARM GOST — desktop application with API

For SaaS without CSP installation requirement — cloud QES via DSS (Directory Services of Signing): the user receives SMS confirmation, the signature is created on the server in a trusted environment. Providers: CryptoPro DSS, Kontur.Crypto, Trusted Environment.

Architecture of Signing via CryptoPro Browser Plugin

// Check for plugin availability
async function checkCryptoProPlugin() {
  try {
    const plugin = await cadesplugin;
    return true;
  } catch (e) {
    return false;
  }
}

// Get list of user certificates
async function getUserCertificates() {
  const plugin = await cadesplugin;
  const store = await plugin.CreateObjectAsync('CAdESCOM.Store');
  await store.Open(
    plugin.CADESCOM_CONTAINER_STORE,
    plugin.CAPICOM_MY_STORE,
    plugin.CAPICOM_STORE_OPEN_MAXIMUM_ALLOWED
  );
  const certs = await store.Certificates;
  const validCerts = await certs.Find(plugin.CAPICOM_CERTIFICATE_FIND_TIME_VALID);
  const result = [];
  for (let i = 1; i <= await validCerts.Count; i++) {
    const cert = await validCerts.Item(i);
    const subjectName = await cert.SubjectName;
    const validTo = await cert.ValidToDate;
    result.push({ index: i, subjectName, validTo, cert });
  }
  await store.Close();
  return result;
}

// Create CAdES-BES signature (attached)
async function signDocumentCAdES(documentBase64, certificateItem) {
  const plugin = await cadesplugin;
  const signer = await plugin.CreateObjectAsync('CAdESCOM.CPSigner');
  await signer.propset_Certificate(certificateItem.cert);
  await signer.propset_CheckCertificate(true);
  const signedData = await plugin.CreateObjectAsync('CAdESCOM.CadesSignedData');
  await signedData.propset_ContentEncoding(plugin.CADESCOM_BASE64_TO_BINARY);
  await signedData.propset_Content(documentBase64);
  const signature = await signedData.SignCades(
    signer,
    plugin.CADESCOM_CADES_BES,
    true
  );
  return signature;
}

Signature Formats

Cloud QES via CryptoPro DSS

No CSP installation on the user's computer required:

// Initialize signing via DSS API
async function initDssSignature(documentHash, userPhone) {
  const response = await fetch('https://dss.cryptopro.ru/SignServer/rest/api/CreateTransactionHash', {
    method: 'POST',
    headers: {
      'Authorization': `Bearer ${process.env.DSS_ACCESS_TOKEN}`,
      'Content-Type': 'application/json',
    },
    body: JSON.stringify({
      Signature: {
        Parameters: {
          CadesType: 1,
          HashAlgorithm: 'GOST3411-2012-256',
        },
        Content: {
          IsDetached: true,
          HashValue: documentHash
        },
      },
      OperationID: crypto.randomUUID(),
    }),
  });
  const { TransactionID } = await response.json();
  await sendConfirmationSms(userPhone, TransactionID);
  return TransactionID;
}

// Confirm with SMS code
async function confirmDssSignature(transactionId, smsCode) {
  const response = await fetch('https://dss.cryptopro.ru/SignServer/rest/api/ConfirmSignature', {
    method: 'POST',
    body: JSON.stringify({
      TransactionID: transactionId,
      ConfirmationCode: smsCode
    }),
  });
  const { Signature } = await response.json();
  return Signature;
}

Signature Verification

async function verifySignature(documentBytes, signatureBase64) {
  const plugin = await cadesplugin;
  const signedData = await plugin.CreateObjectAsync('CAdESCOM.CadesSignedData');
  await signedData.propset_ContentEncoding(plugin.CADESCOM_BASE64_TO_BINARY);
  await signedData.propset_Content(Buffer.from(documentBytes).toString('base64'));
  await signedData.VerifyCades(signatureBase64, plugin.CADESCOM_CADES_BES, true);
  const signers = await signedData.Signers;
  const signer = await signers.Item(1);
  const cert = await signer.Certificate;
  const certInfo = await cert.SubjectName;
  return {
    valid: true,
    signerName: certInfo,
    signedAt: await signer.SigningTime,
  };
}

Legal Requirements

• The certificate must be issued by an accredited CA (registry on the Ministry of Digital Development website)
• The CSP must be certified by the FSB (Federal Law No. 63-FZ "On Electronic Signature")
• Additional requirements for real estate transactions, notarial acts
• Storage of QES-signed documents — at least the statute of limitations (3–10 years)

What's Included in QES Integration

• Audit of the current electronic document flow scheme
• Selection of the appropriate method: plugin, cloud, or combined
• UI development for certificate selection and signature display
• Integration with CryptoPro Browser Plugin or DSS API
• Testing on all target browsers (Chrome, Yandex, Firefox, Safari)
• User training and documentation
• Technical support after launch

Timeline

Integration with CryptoPro Browser Plugin: UI, certificate list, CAdES-BES signing — 7–10 days. Cloud QES via CryptoPro DSS with SMS confirmation — 7–10 days. Signature verification with certificate check — 3–5 days. Full turnkey project — from 14 business days. In 90% of cases, we meet the 14-day deadline.

Request a demonstration of QES on your project — get an engineer consultation. Get a consultation — we will select the optimal solution for your business and prepare a commercial proposal.