Create a subordinate certificate authority

This page describes how to create subordinate certificate authorities (CAs) in a CA pool.

Subordinate CAs are responsible for issuing certificates directly to end-entities such as users, computers, and devices. Subordinate CAs are cryptographically signed by a parent CA, which is often the root CA. As a result, systems that trust the root CA, automatically trust the subordinate CAs and the end-entity certificates that the subordinate CAs issue.

Before you begin

• Make sure you have the CA Service Operation Manager (roles/privateca.caManager) or the CA Service Admin (roles/privateca.admin) IAM role. For information, see Configure IAM policies.
• Create a CA pool.
• Select your root CA.

Create a subordinate CA

Subordinate CAs are easier to revoke and rotate than root CAs. If you have multiple certificate issuance scenarios, you can create a subordinate CA for each of those scenarios. Adding multiple subordinate CAs in a CA pool helps you achieve better load-balancing of certificate requests and a higher total effective QPS.

To create a subordinate CA, do the following:

Console

1. Go to the Certificate Authority Service page in the Google Cloud console.

   Go to Certificate Authority Service

2. Click the CA manager tab.

3. Click Create CA.

   

Select CA type

1. Click Subordinate CA.
2. Click Root CA is in Google Cloud.
3. In the Valid for field, enter the duration for which you want the CA certificate to be valid.
4. Optional: Choose the tier for the CA. The default tier is Enterprise. For more information, see Select the operation tiers.
5. Click Region to select a location for the CA. For more information, see Locations.
6. Optional: Under Initialized state, select the state the CA must be in at creation.
7. Optional: Under Set up an issuance scenario, click Certificate profile and select the certificate profile that best suits your requirements from the list. For more information, see Certificate profiles.
8. Click Next.

Configure CA subject name

1. In the Organization (O) field, enter the name of your company.
2. Optional: In the Organization unit (OU) field, enter the company subdivision or business unit.
3. Optional: In the Country name field, enter a two letter country code.
4. Optional: In the State or province name field, enter the name of your state.
5. Optional: In the Locality name field, enter the name of your city.
6. In the CA common name (CN) field, enter the CA name.
7. In the Pool ID field, enter the CA pool name. You cannot change the CA pool after creating the CA.
8. Click Next.

Configure CA key size and algorithm

1. Choose the key algorithm that best meets your needs. For information about deciding the suitable key algorithm, see Choose a key algorithm.
2. Click Next.

Configure CA artifacts

The following steps are optional. If you skip these steps, the default settings apply.

1. Choose whether you want to use a Google-managed or a self-managed Cloud Storage bucket.

If you don't select a self-managed Cloud Storage bucket, CA Service creates a Google-managed bucket in the same location as the CA.

2. Choose whether you want to disable the publication of certificate revocation lists (CRLs) and CA certificates to the Cloud Storage bucket.

The publication of CRL and CA certificate on a Cloud Storage bucket is enabled by default. To disable these settings, click the toggles.

3. Click Next.

Add labels

The following steps are optional.

If you want to add labels to the CA, do the following:

1. Click Add item.
2. In the Key 1 field, enter the label key.
3. In the Value 1 field, enter the label value.
4. If you want to add another label, click Add item. Then, add the label key and value as mentioned in steps 2 and 3.
5. Click Next.

Review the settings

Carefully review all the settings, then click Create to create the CA.

gcloud

1. Create a CA pool for the subordinate CA:

   gcloud privateca pools create SUBORDINATE_POOL_ID
   

   Replace SUBORDINATE_POOL_ID with the name of the CA pool.

   For more information about creating CA pools, see Create a CA pool.

   For more information about the gcloud privateca pools create command, see gcloud privateca pools create.

2. Create a subordinate CA in the created CA pool.

   Note: You can obtain the issuer's resource ID (POOL_ID) by copying the ID from the create command, or by leveraging the gcloud privateca pools list command.

   gcloud privateca subordinates create SUBORDINATE_CA_ID \
     --pool=SUBORDINATE_POOL_ID \
     --issuer-pool=POOL_ID \
     --key-algorithm="ec-p256-sha256" \
     --subject="CN=Example Server TLS CA, O=Example LLC"
   

   The following statement is returned when the subordinate CA is created.

   Created Certificate Authority [projects/my-project-pki/locations/us-west1/caPools/SUBORDINATE_POOL_ID/certificateAuthorities/SUBORDINATE_CA_ID].
   

   To see an exhaustive list of settings, run the following gcloud command:

   gcloud privateca subordinates create --help
   

   The command returns examples to create a subordinate CA whose issuer is either located on CA Service or located elsewhere.

Terraform

resource "google_privateca_certificate_authority" "root_ca" {
  // This example assumes this pool already exists.
  // Pools cannot be deleted in normal test circumstances, so we depend on static pools
  pool                                   = "my-pool"
  certificate_authority_id               = "my-certificate-authority-root"
  location                               = "us-central1"
  deletion_protection                    = false # set to true to prevent destruction of the resource
  ignore_active_certificates_on_deletion = true
  config {
    subject_config {
      subject {
        organization = "ACME"
        common_name  = "my-certificate-authority"
      }
    }
    x509_config {
      ca_options {
        # is_ca *MUST* be true for certificate authorities
        is_ca = true
      }
      key_usage {
        base_key_usage {
          # cert_sign and crl_sign *MUST* be true for certificate authorities
          cert_sign = true
          crl_sign  = true
        }
        extended_key_usage {
        }
      }
    }
  }
  key_spec {
    algorithm = "RSA_PKCS1_4096_SHA256"
  }
  // valid for 10 years
  lifetime = "${10 * 365 * 24 * 3600}s"
}

resource "google_privateca_certificate_authority" "sub_ca" {
  // This example assumes this pool already exists.
  // Pools cannot be deleted in normal test circumstances, so we depend on static pools
  pool                     = "my-sub-pool"
  certificate_authority_id = "my-certificate-authority-sub"
  location                 = "us-central1"
  deletion_protection      = false # set to true to prevent destruction of the resource
  subordinate_config {
    certificate_authority = google_privateca_certificate_authority.root_ca.name
  }
  config {
    subject_config {
      subject {
        organization = "ACME"
        common_name  = "my-subordinate-authority"
      }
    }
    x509_config {
      ca_options {
        is_ca = true
        # Force the sub CA to only issue leaf certs.
        # Use e.g.
        #    max_issuer_path_length = 1
        # if you need to chain more subordinates.
        zero_max_issuer_path_length = true
      }
      key_usage {
        base_key_usage {
          cert_sign = true
          crl_sign  = true
        }
        extended_key_usage {
        }
      }
    }
  }
  // valid for 5 years
  lifetime = "${5 * 365 * 24 * 3600}s"
  key_spec {
    algorithm = "RSA_PKCS1_2048_SHA256"
  }
  type = "SUBORDINATE"
}

Java

To authenticate to CA Service, set up Application Default Credentials. For more information, see Set up authentication for a local development environment.

import com.google.api.core.ApiFuture;
import com.google.cloud.security.privateca.v1.CaPoolName;
import com.google.cloud.security.privateca.v1.CertificateAuthority;
import com.google.cloud.security.privateca.v1.CertificateAuthority.KeyVersionSpec;
import com.google.cloud.security.privateca.v1.CertificateAuthority.SignHashAlgorithm;
import com.google.cloud.security.privateca.v1.CertificateAuthorityServiceClient;
import com.google.cloud.security.privateca.v1.CertificateConfig;
import com.google.cloud.security.privateca.v1.CertificateConfig.SubjectConfig;
import com.google.cloud.security.privateca.v1.CreateCertificateAuthorityRequest;
import com.google.cloud.security.privateca.v1.KeyUsage;
import com.google.cloud.security.privateca.v1.KeyUsage.KeyUsageOptions;
import com.google.cloud.security.privateca.v1.Subject;
import com.google.cloud.security.privateca.v1.SubjectAltNames;
import com.google.cloud.security.privateca.v1.X509Parameters;
import com.google.cloud.security.privateca.v1.X509Parameters.CaOptions;
import com.google.longrunning.Operation;
import com.google.protobuf.Duration;
import java.io.IOException;
import java.util.concurrent.ExecutionException;

public class CreateSubordinateCa {

  public static void main(String[] args)
      throws InterruptedException, ExecutionException, IOException {
    // TODO(developer): Replace these variables before running the sample.
    // location: For a list of locations, see:
    // https://cloud.google.com/certificate-authority-service/docs/locations
    // poolId: Set it to the CA Pool under which the CA should be created.
    // subordinateCaName: Unique name for the Subordinate CA.
    String project = "your-project-id";
    String location = "ca-location";
    String poolId = "ca-pool-id";
    String subordinateCaName = "subordinate-certificate-authority-name";

    createSubordinateCertificateAuthority(project, location, poolId, subordinateCaName);
  }

  public static void createSubordinateCertificateAuthority(
      String project, String location, String poolId, String subordinateCaName)
      throws IOException, ExecutionException, InterruptedException {
    // Initialize client that will be used to send requests. This client only needs to be created
    // once, and can be reused for multiple requests. After completing all of your requests, call
    // the `certificateAuthorityServiceClient.close()` method on the client to safely
    // clean up any remaining background resources.
    try (CertificateAuthorityServiceClient certificateAuthorityServiceClient =
        CertificateAuthorityServiceClient.create()) {

      String commonName = "commonname";
      String orgName = "csr-org-name";
      String domainName = "dns.example.com";
      int caDuration = 100000; // Validity of this CA in seconds.

      // Set the type of Algorithm.
      KeyVersionSpec keyVersionSpec =
          KeyVersionSpec.newBuilder().setAlgorithm(SignHashAlgorithm.RSA_PKCS1_4096_SHA256).build();

      // Set CA subject config.
      SubjectConfig subjectConfig =
          SubjectConfig.newBuilder()
              .setSubject(
                  Subject.newBuilder().setCommonName(commonName).setOrganization(orgName).build())
              // Set the fully qualified domain name.
              .setSubjectAltName(SubjectAltNames.newBuilder().addDnsNames(domainName).build())
              .build();

      //  Set the key usage options for X.509 fields.
      X509Parameters x509Parameters =
          X509Parameters.newBuilder()
              .setKeyUsage(
                  KeyUsage.newBuilder()
                      .setBaseKeyUsage(
                          KeyUsageOptions.newBuilder().setCrlSign(true).setCertSign(true).build())
                      .build())
              .setCaOptions(CaOptions.newBuilder().setIsCa(true).build())
              .build();

      // Set certificate authority settings.
      CertificateAuthority subCertificateAuthority =
          CertificateAuthority.newBuilder()
              .setType(CertificateAuthority.Type.SUBORDINATE)
              .setKeySpec(keyVersionSpec)
              .setConfig(
                  CertificateConfig.newBuilder()
                      .setSubjectConfig(subjectConfig)
                      .setX509Config(x509Parameters)
                      .build())
              // Set the CA validity duration.
              .setLifetime(Duration.newBuilder().setSeconds(caDuration).build())
              .build();

      // Create the CertificateAuthorityRequest.
      CreateCertificateAuthorityRequest subCertificateAuthorityRequest =
          CreateCertificateAuthorityRequest.newBuilder()
              .setParent(CaPoolName.of(project, location, poolId).toString())
              .setCertificateAuthorityId(subordinateCaName)
              .setCertificateAuthority(subCertificateAuthority)
              .build();

      // Create Subordinate CA.
      ApiFuture<Operation> futureCall =
          certificateAuthorityServiceClient
              .createCertificateAuthorityCallable()
              .futureCall(subCertificateAuthorityRequest);

      Operation response = futureCall.get();

      if (response.hasError()) {
        System.out.println("Error while creating Subordinate CA !" + response.getError());
        return;
      }

      System.out.println(
          "Subordinate Certificate Authority created successfully : " + subordinateCaName);
    }
  }
}

Python

To authenticate to CA Service, set up Application Default Credentials. For more information, see Set up authentication for a local development environment.

import google.cloud.security.privateca_v1 as privateca_v1
from google.protobuf import duration_pb2


def create_subordinate_ca(
    project_id: str,
    location: str,
    ca_pool_name: str,
    subordinate_ca_name: str,
    common_name: str,
    organization: str,
    domain: str,
    ca_duration: int,
) -> None:
    """
    Create Certificate Authority (CA) which is the subordinate CA in the given CA Pool.
    Args:
        project_id: project ID or project number of the Cloud project you want to use.
        location: location you want to use. For a list of locations, see: https://cloud.google.com/certificate-authority-service/docs/locations.
        ca_pool_name: set it to the CA Pool under which the CA should be created.
        subordinate_ca_name: unique name for the Subordinate CA.
        common_name: a title for your certificate authority.
        organization: the name of your company for your certificate authority.
        domain: the name of your company for your certificate authority.
        ca_duration: the validity of the certificate authority in seconds.
    """

    ca_service_client = privateca_v1.CertificateAuthorityServiceClient()

    # Set the type of Algorithm
    key_version_spec = privateca_v1.CertificateAuthority.KeyVersionSpec(
        algorithm=privateca_v1.CertificateAuthority.SignHashAlgorithm.RSA_PKCS1_4096_SHA256
    )

    # Set CA subject config.
    subject_config = privateca_v1.CertificateConfig.SubjectConfig(
        subject=privateca_v1.Subject(
            common_name=common_name, organization=organization
        ),
        # Set the fully qualified domain name.
        subject_alt_name=privateca_v1.SubjectAltNames(dns_names=[domain]),
    )

    # Set the key usage options for X.509 fields.
    x509_parameters = privateca_v1.X509Parameters(
        key_usage=privateca_v1.KeyUsage(
            base_key_usage=privateca_v1.KeyUsage.KeyUsageOptions(
                crl_sign=True,
                cert_sign=True,
            )
        ),
        ca_options=privateca_v1.X509Parameters.CaOptions(
            is_ca=True,
        ),
    )

    # Set certificate authority settings.
    certificate_authority = privateca_v1.CertificateAuthority(
        type_=privateca_v1.CertificateAuthority.Type.SUBORDINATE,
        key_spec=key_version_spec,
        config=privateca_v1.CertificateConfig(
            subject_config=subject_config,
            x509_config=x509_parameters,
        ),
        # Set the CA validity duration.
        lifetime=duration_pb2.Duration(seconds=ca_duration),
    )

    ca_pool_path = ca_service_client.ca_pool_path(project_id, location, ca_pool_name)

    # Create the CertificateAuthorityRequest.
    request = privateca_v1.CreateCertificateAuthorityRequest(
        parent=ca_pool_path,
        certificate_authority_id=subordinate_ca_name,
        certificate_authority=certificate_authority,
    )

    operation = ca_service_client.create_certificate_authority(request=request)
    result = operation.result()

    print(f"Operation result: {result}")

Enable a subordinate CA

To enable a subordinate CA, do the following:

Console

1. Go to the Certificate Authority Service page in the Google Cloud console.

   Go to Certificate Authority Service

2. Click the CA manager tab.

3. Under Certificate authorities, select the CA that you want to activate.

4. Click Activate.

5. In the dialog that opens, click Download CSR to download the PEM-encoded CSR file that the issuing CA can sign.

6. Click Next.

7. In the Upload Certificate Chain field, click Browse.

8. Upload the signed certificate file with .crt extension.

9. Click Activate.

gcloud

To enable a newly created subordinate CA, run the following command:

gcloud privateca subordinates enable SUBORDINATE_CA_ID --pool=SUBORDINATE_POOL_ID

Replace the following:

• SUBORDINATE_CA_ID: the unique identifier of the subordinate CA.
• SUBORDINATE_POOL_ID: the name of the CA pool that contains the subordinate CA.

For more information about the gcloud privateca subordinates enable command, see gcloud privateca subordinates enable.

Terraform

Set field desired_state to ENABLED on the subordinate CA and run terraform apply.

Note: CA Service doesn't check the revocation status of the root CA before enabling a subordinate CA that chains up to it. The only exception to this policy is when you have created the root CA using CA Service. In this scenario, CA Service checks the revocation status of the root CA daily. If the root CA is revoked, CA Service updates the privateca.googleapis.com/ca/cert_revoked metric on the subordinate CA.

What's next

• Learn how to request certificates.
• Learn about templates and issuance policies.