# Certificate Chain Development

This topic walks you through on how to create a certificate chain object, obtain information about the certificates of the certificate chain, and validate the certificate chain using a trust anchor.

## How to Develop

1. Import the [certFramework](../../reference/apis-device-certificate-kit/js-apis-cert.md) module.

   ```ts
   import { cert } from '@kit.DeviceCertificateKit';
   ```

2. Use [cert.createX509CertChain](../../reference/apis-device-certificate-kit/js-apis-cert.md#certcreatex509certchain11) to create an X.509 certificate chain (**X509CertChain**) object.

3. Use [x509CertChain.getCertList](../../reference/apis-device-certificate-kit/js-apis-cert.md#getcertlist11) to obtain information about the X.509 certificates of the certificate chain.

4. Use [x509CertChain.validate](../../reference/apis-device-certificate-kit/js-apis-cert.md#validate11) to validate the certificate chain.

```ts
import { cert } from '@kit.DeviceCertificateKit';
import { BusinessError } from '@kit.BasicServicesKit';
import { util } from '@kit.ArkTS';

let certChainData = "-----BEGIN CERTIFICATE-----\n" +
  "MIID6jCCAtKgAwIBAgIIIM2q/TmRoLcwDQYJKoZIhvcNAQELBQAwWjELMAkGA1UE\n" +
  "BhMCRU4xEDAOBgNVBAgTB0VuZ2xhbmQxDzANBgNVBAcTBkxvbmRvbjEMMAoGA1UE\n" +
  "ChMDdHMyMQwwCgYDVQQLEwN0czIxDDAKBgNVBAMTA3RzMjAeFw0yMzEyMDUwNzM5\n" +
  "MDBaFw0yNDEwMzEyMzU5MDBaMGExCzAJBgNVBAYTAkNOMRAwDgYDVQQIEwdKaWFu\n" +
  "Z3N1MRAwDgYDVQQHEwdOYW5qaW5nMQwwCgYDVQQKEwN0czMxDDAKBgNVBAsTA3Rz\n" +
  "MzESMBAGA1UEAxMJMTI3LjAuMC4xMIIBIjANBgkqhkiG9w0BAQEFAAOCAQ8AMIIB\n" +
  "CgKCAQEAtt+2QxUevbolYLp51QGcUpageI4fwGLIqv4fj4aoVnHFOOBqVOVpfCLR\n" +
  "p26LFV/F8ebwPyo8YEBKSwXzMD1573rMSbaH9BalscH5lZYAbetXoio6YRvzlcmc\n" +
  "rVvLBNMeVnxY86xHpo0MTNyP7W024rZsxWO98xFQVdoiaBC+7+midlisx2Y+7u0j\n" +
  "zT9GjeUP6JLdLFUZJKUPSTK3jVzw9v1eZQZKYoNfU6vFMd6ndtwW6qEnwpzmmX/U\n" +
  "T+p5ThAMH593zszlz330nTSXBjIsGkyvOz9gSB0Z0LAuJj06XUNhGL5xKJYKbdI3\n" +
  "8MFQFJKvRHfgTAvVsvAvpBUM2DuBKwIDAQABo4GsMIGpMAkGA1UdEwQCMAAwHQYD\n" +
  "VR0OBBYEFDfsHTMZwoA6eaDFlBUyDpka+sYtMAsGA1UdDwQEAwID+DAnBgNVHSUE\n" +
  "IDAeBggrBgEFBQcDAQYIKwYBBQUHAwIGCCsGAQUFBwMEMBQGA1UdEQQNMAuCCTEy\n" +
  "Ny4wLjAuMTARBglghkgBhvhCAQEEBAMCBkAwHgYJYIZIAYb4QgENBBEWD3hjYSBj\n" +
  "ZXJ0aWZpY2F0ZTANBgkqhkiG9w0BAQsFAAOCAQEAp5vTvXrt8ZpgRJVtzv9ss0lJ\n" +
  "izp1fJf+ft5cDXrs7TSD5oHrSW2vk/ZieIMhexU4LFwhs4OE7jK6pgI48Dseqxx7\n" +
  "B/KktxhVMJUmVXd9Ayjp6f+BtZlIk0cArPuoXToXjsV8caTGBXHRdzxpAk/w9syc\n" +
  "GYrbH9TrdNMuTizOb+k268oKXUageZNxHmd7YvOXkcNgrd29jzwXKDYYiUa1DISz\n" +
  "DnYaJOgPt0B/5izhoWNK7GhJDy9KEuLURcTSWFysbbnljwO9INPT9MmlS83PdAgN\n" +
  "iS8VXF4pce1W9U5jH7d7k0JDVSXybebe1iPFphsZpYM/NE+jap+mPy1nTCbf9g==\n" +
  "-----END CERTIFICATE-----\n" +
  "-----BEGIN CERTIFICATE-----\n" +
  "MIIC0zCCAoWgAwIBAgIIXpLoPpQVWnkwBQYDK2VwMFoxCzAJBgNVBAYTAkVOMRAw\n" +
  "DgYDVQQIEwdFbmdsYW5kMQ8wDQYDVQQHEwZMb25kb24xDDAKBgNVBAoTA3RzMTEM\n" +
  "MAoGA1UECxMDdHMxMQwwCgYDVQQDEwN0czEwHhcNMjMxMjA1MDczNzAwWhcNMjQw\n" +
  "OTAxMjM1OTAwWjBaMQswCQYDVQQGEwJFTjEQMA4GA1UECBMHRW5nbGFuZDEPMA0G\n" +
  "A1UEBxMGTG9uZG9uMQwwCgYDVQQKEwN0czIxDDAKBgNVBAsTA3RzMjEMMAoGA1UE\n" +
  "AxMDdHMyMIIBIjANBgkqhkiG9w0BAQEFAAOCAQ8AMIIBCgKCAQEAtt+2QxUevbol\n" +
  "YLp51QGcUpageI4fwGLIqv4fj4aoVnHFOOBqVOVpfCLRp26LFV/F8ebwPyo8YEBK\n" +
  "SwXzMD1573rMSbaH9BalscH5lZYAbetXoio6YRvzlcmcrVvLBNMeVnxY86xHpo0M\n" +
  "TNyP7W024rZsxWO98xFQVdoiaBC+7+midlisx2Y+7u0jzT9GjeUP6JLdLFUZJKUP\n" +
  "STK3jVzw9v1eZQZKYoNfU6vFMd6ndtwW6qEnwpzmmX/UT+p5ThAMH593zszlz330\n" +
  "nTSXBjIsGkyvOz9gSB0Z0LAuJj06XUNhGL5xKJYKbdI38MFQFJKvRHfgTAvVsvAv\n" +
  "pBUM2DuBKwIDAQABo28wbTAMBgNVHRMEBTADAQH/MB0GA1UdDgQWBBQ37B0zGcKA\n" +
  "OnmgxZQVMg6ZGvrGLTALBgNVHQ8EBAMCAQYwEQYJYIZIAYb4QgEBBAQDAgAHMB4G\n" +
  "CWCGSAGG+EIBDQQRFg94Y2EgY2VydGlmaWNhdGUwBQYDK2VwA0EAuasLBe55YgvF\n" +
  "b4wmHeohylc9r8cFGS1LNQ5UcSn3sGqMYf6ehnef16NLuCW6upHCs8Sui4iAMvsP\n" +
  "uKPWR9dKBA==\n" +
  "-----END CERTIFICATE-----\n" +
  "-----BEGIN CERTIFICATE-----\n"  +
  "MIIB3zCCAZGgAwIBAgIIWQvOEDl+ya4wBQYDK2VwMFoxCzAJBgNVBAYTAkVOMRAw\n" +
  "DgYDVQQIEwdFbmdsYW5kMQ8wDQYDVQQHEwZMb25kb24xDDAKBgNVBAoTA3RzMTEM\n" +
  "MAoGA1UECxMDdHMxMQwwCgYDVQQDEwN0czEwHhcNMjMxMjA1MDAwMDAwWhcNMjQx\n" +
  "MjA0MjM1OTU5WjBaMQswCQYDVQQGEwJFTjEQMA4GA1UECBMHRW5nbGFuZDEPMA0G\n" +
  "A1UEBxMGTG9uZG9uMQwwCgYDVQQKEwN0czExDDAKBgNVBAsTA3RzMTEMMAoGA1UE\n" +
  "AxMDdHMxMCowBQYDK2VwAyEAuxadj1ww0LqPN24zr28jcSOlSWAe0QdLyRF+ZgG6\n" +
  "klKjdTBzMBIGA1UdEwEB/wQIMAYBAf8CARQwHQYDVR0OBBYEFNSgpoQvfxR8A1Y4\n" +
  "St8NjOHkRpm4MAsGA1UdDwQEAwIBBjARBglghkgBhvhCAQEEBAMCAAcwHgYJYIZI\n" +
  "AYb4QgENBBEWD3hjYSBjZXJ0aWZpY2F0ZTAFBgMrZXADQQAblBgoa72X/K13WOvc\n" +
  "KW0fqBgFKvLy85hWD6Ufi61k4ProQiZzMK+0+y9jReKelPx/zRdCCgSbQroAR2mV\n" +
  "xjoE\n" +
  "-----END CERTIFICATE-----\n";

async function sample() {
  let textEncoder = new util.TextEncoder();
  // Certificate chain binary data, which may vary with the service.
  const encodingBlob: cert.EncodingBlob = {
    data: textEncoder.encodeInto(certChainData),
    // Set the encoding format, which can be FORMAT_PEM, FORMAT_DER, or FORMAT_PKCS7.
    encodingFormat: cert.EncodingFormat.FORMAT_PEM
  };
  let x509CertChain: cert.X509CertChain = {} as cert.X509CertChain;
  try {
    x509CertChain = await cert.createX509CertChain(encodingBlob);
  } catch (err) {
    let e: BusinessError = err as BusinessError;
    console.error(`createX509CertChain failed, errCode: ${e.code}, errMsg: ${e.message}`);
  }

  try {
    let certList = x509CertChain.getCertList();
  } catch (err) {
    let e: BusinessError = err as BusinessError;
    console.error(`X509CertChain getCertList failed, errCode: ${e.code}, errMsg: ${e.message}`);
  }

  // Certificate chain validation data, which may vary with the service.
  const param: cert.CertChainValidationParameters = {
    date: '20231212080000Z',
    trustAnchors: [{
      CAPubKey: new Uint8Array([0x30, 0x2a, 0x30, 0x05, 0x06, 0x03, 0x2b, 0x65, 0x70, 0x03, 0x21, 0x00, 0xbb, 0x16,0x9d, 0x8f, 0x5c, 0x30, 0xd0, 0xba, 0x8f, 0x37, 0x6e, 0x33, 0xaf, 0x6f, 0x23, 0x71, 0x23, 0xa5, 0x49, 0x60,0x1e, 0xd1, 0x07, 0x4b, 0xc9, 0x11, 0x7e, 0x66, 0x01, 0xba, 0x92, 0x52]),
      CASubject: new Uint8Array([0x30, 0x5a, 0x31, 0x0b, 0x30, 0x09, 0x06, 0x03, 0x55, 0x04, 0x06, 0x13, 0x02, 0x45,0x4e, 0x31, 0x10, 0x30, 0x0e, 0x06, 0x03, 0x55, 0x04, 0x08, 0x13, 0x07, 0x45, 0x6e, 0x67, 0x6c, 0x61, 0x6e,0x64, 0x31, 0x0f, 0x30, 0x0d, 0x06, 0x03, 0x55, 0x04, 0x07, 0x13, 0x06, 0x4c, 0x6f, 0x6e, 0x64, 0x6f, 0x6e,0x31, 0x0c, 0x30, 0x0a, 0x06, 0x03, 0x55, 0x04, 0x0a, 0x13, 0x03, 0x74, 0x73, 0x31, 0x31, 0x0c, 0x30, 0x0a,0x06, 0x03, 0x55, 0x04, 0x0b, 0x13, 0x03, 0x74, 0x73, 0x31, 0x31, 0x0c, 0x30, 0x0a, 0x06, 0x03, 0x55, 0x04,0x03, 0x13, 0x03, 0x74, 0x73, 0x31]),
    }]
  };
  try {
    const validationRes = await x509CertChain.validate(param);
    console.log('X509CertChain validate success');
  } catch (err) {
    console.error('X509CertChain validate failed');
  }
}
```