# Activate a Product Attestation Authority (PAA)
<a name="JavaApiCBC-ProductAttestationAuthorityActivation"></a>

This Java sample shows how to use the [RootCACertificate\$1APIPassthrough/V1 definition](template-definitions.md#RootCACertificate_APIPassthrough) template to create and install a [Matter](https://buildwithmatter.com) Root CA (PAA) certificate for product attestation. The AuthorityKeyIdentifier (AKI) extension is optional for PAAs. To set an AKI, you must generate a Base64-encoded AKI value and pass it through a CustomExtension.

The example calls the following AWS Private CA API actions:
+ [CreateCertificateAuthority](https://docs.aws.amazon.com/privateca/latest/APIReference/API_CreateCertificateAuthority.html)
+ [GetCertificateAuthorityCsr](https://docs.aws.amazon.com/privateca/latest/APIReference/API_GetCertificateAuthorityCsr.html)
+ [IssueCertificate](https://docs.aws.amazon.com/privateca/latest/APIReference/API_IssueCertificate.html)
+ [GetCertificate](https://docs.aws.amazon.com/privateca/latest/APIReference/API_GetCertificate.html)
+ [ImportCertificateAuthorityCertificate](https://docs.aws.amazon.com/privateca/latest/APIReference/API_ImportCertificateAuthorityCertificate.html)

If you encounter problems, see [Troubleshoot AWS Private CA Matter-compliant certificate errorsMatter-compliant certificate errors](TroubleshootPcaMatter.md) in the Troubleshooting section.

```
package com.amazonaws.samples.matter;

import com.amazonaws.auth.AWSCredentials;
import com.amazonaws.auth.profile.ProfileCredentialsProvider;
import com.amazonaws.client.builder.AwsClientBuilder;
import com.amazonaws.client.builder.AwsClientBuilder.EndpointConfiguration;
import com.amazonaws.samples.GetCertificateAuthorityCertificate;
import com.amazonaws.auth.AWSStaticCredentialsProvider;


import com.amazonaws.services.acmpca.AWSACMPCA;
import com.amazonaws.services.acmpca.AWSACMPCAClientBuilder;

import com.amazonaws.services.acmpca.model.ASN1Subject;
import com.amazonaws.services.acmpca.model.ApiPassthrough;
import com.amazonaws.services.acmpca.model.CertificateAuthorityConfiguration;
import com.amazonaws.services.acmpca.model.CertificateAuthorityType;
import com.amazonaws.services.acmpca.model.CreateCertificateAuthorityResult;
import com.amazonaws.services.acmpca.model.CreateCertificateAuthorityRequest;
import com.amazonaws.services.acmpca.model.CrlConfiguration;
import com.amazonaws.services.acmpca.model.CustomAttribute;
import com.amazonaws.services.acmpca.model.CustomExtension;
import com.amazonaws.services.acmpca.model.Extensions;
import com.amazonaws.services.acmpca.model.KeyAlgorithm;
import com.amazonaws.services.acmpca.model.SigningAlgorithm;
import com.amazonaws.services.acmpca.model.Tag;

import java.io.ByteArrayInputStream;
import java.io.InputStreamReader;
import java.nio.ByteBuffer;
import java.nio.charset.StandardCharsets;
import java.util.ArrayList;
import java.util.Arrays;
import java.util.Base64;
import java.util.List;
import java.util.Objects;

import com.amazonaws.services.acmpca.model.GetCertificateAuthorityCsrRequest;
import com.amazonaws.services.acmpca.model.GetCertificateAuthorityCsrResult;
import com.amazonaws.services.acmpca.model.GetCertificateRequest;
import com.amazonaws.services.acmpca.model.GetCertificateResult;
import com.amazonaws.services.acmpca.model.ImportCertificateAuthorityCertificateRequest;
import com.amazonaws.services.acmpca.model.IssueCertificateRequest;
import com.amazonaws.services.acmpca.model.IssueCertificateResult;
import com.amazonaws.services.acmpca.model.SigningAlgorithm;
import com.amazonaws.services.acmpca.model.Validity;
import com.amazonaws.services.acmpca.model.RevocationConfiguration;
import com.amazonaws.services.acmpca.model.CrlConfiguration;
import com.amazonaws.services.acmpca.model.CrlDistributionPointExtensionConfiguration;

import com.amazonaws.AmazonClientException;
import com.amazonaws.services.acmpca.model.CertificateMismatchException;
import com.amazonaws.services.acmpca.model.ConcurrentModificationException;
import com.amazonaws.services.acmpca.model.LimitExceededException;
import com.amazonaws.services.acmpca.model.InvalidArgsException;
import com.amazonaws.services.acmpca.model.InvalidArnException;
import com.amazonaws.services.acmpca.model.InvalidPolicyException;
import com.amazonaws.services.acmpca.model.InvalidStateException;
import com.amazonaws.services.acmpca.model.MalformedCertificateException;
import com.amazonaws.services.acmpca.model.MalformedCSRException;
import com.amazonaws.services.acmpca.model.RequestFailedException;
import com.amazonaws.services.acmpca.model.RequestInProgressException;
import com.amazonaws.services.acmpca.model.ResourceNotFoundException;
import com.amazonaws.services.acmpca.model.AWSACMPCAException;

import com.amazonaws.waiters.Waiter;
import com.amazonaws.waiters.WaiterParameters;
import com.amazonaws.waiters.WaiterTimedOutException;
import com.amazonaws.waiters.WaiterUnrecoverableException;

import org.bouncycastle.asn1.x509.SubjectPublicKeyInfo;
import org.bouncycastle.cert.jcajce.JcaX509ExtensionUtils;
import org.bouncycastle.openssl.PEMParser;
import org.bouncycastle.pkcs.PKCS10CertificationRequest;
import org.bouncycastle.util.io.pem.PemReader;

import lombok.SneakyThrows;

public class ProductAttestationAuthorityActivation {

    public static void main(String[] args) throws Exception {
        // Define the endpoint region for your sample.
        String endpointRegion = "region";  // Substitute your region here, e.g. "ap-southeast-2"

        // Define custom attributes
        List<CustomAttribute> customAttributes = Arrays.asList(
            new CustomAttribute()
                .withObjectIdentifier("2.5.4.3") // CommonName
                .withValue("Matter Test PAA"),
            new CustomAttribute()
                .withObjectIdentifier("1.3.6.1.4.1.37244.2.1") // Vendor ID
                .withValue("FFF1")
        );

        // Define a CA subject.
        ASN1Subject subject = new ASN1Subject();
        subject.setCustomAttributes(customAttributes);

        // Define the CA configuration.
        CertificateAuthorityConfiguration configCA = new CertificateAuthorityConfiguration();
        configCA.withKeyAlgorithm(KeyAlgorithm.EC_prime256v1);
        configCA.withSigningAlgorithm(SigningAlgorithm.SHA256WITHECDSA);
        configCA.withSubject(subject);

        // Define a CRL distribution point extension configuration
        CrlDistributionPointExtensionConfiguration CDPConfigure = new CrlDistributionPointExtensionConfiguration();
        CDPConfigure.withOmitExtension(true);

        // Define a certificate revocation list configuration.
        CrlConfiguration crlConfigure = new CrlConfiguration();
        crlConfigure.withEnabled(true);
        crlConfigure.withExpirationInDays(365);
        crlConfigure.withCustomCname(null);
        crlConfigure.withS3BucketName("your-bucket-name");
        crlConfigure.withS3ObjectAcl("BUCKET_OWNER_FULL_CONTROL");
        crlConfigure.withCrlDistributionPointExtensionConfiguration(CDPConfigure);

        // Define a certificate authority type
        CertificateAuthorityType CAtype = CertificateAuthorityType.ROOT;

        // ** Execute core code samples for Root CA activation in sequence **
        AWSACMPCA client = ClientBuilder(endpointRegion);
        String rootCAArn = CreateCertificateAuthority(configCA, crlConfigure, CAtype, client);
        String csr = GetCertificateAuthorityCsr(rootCAArn, client);
        String rootCertificateArn = IssueCertificate(rootCAArn, csr, client);
        String rootCertificate = GetCertificate(rootCertificateArn, rootCAArn, client);
        ImportCertificateAuthorityCertificate(rootCertificate, rootCAArn, client);
    }

    private static AWSACMPCA ClientBuilder(String endpointRegion) {
        // Retrieve your credentials from the C:\Users\name\.aws\credentials file
        // in Windows or the .aws/credentials file in Linux.
        AWSCredentials credentials = null;
        try {
            credentials = new ProfileCredentialsProvider("default").getCredentials();
        } catch (Exception e) {
            throw new AmazonClientException(
                    "Cannot load the credentials from the credential profiles file. " +
                    "Please make sure that your credentials file is at the correct " +
                    "location (C:\\Users\\joneps\\.aws\\credentials), and is in valid format.",
                    e);
        }

        String endpointProtocol = "https://acm-pca." + endpointRegion + ".amazonaws.com/";
        EndpointConfiguration endpoint =
            new AwsClientBuilder.EndpointConfiguration(endpointProtocol, endpointRegion);
        
        // Create a client that you can use to make requests.
        AWSACMPCA client = AWSACMPCAClientBuilder.standard()
            .withEndpointConfiguration(endpoint)
            .withCredentials(new AWSStaticCredentialsProvider(credentials))
            .build();

        return client;
    }

    private static String CreateCertificateAuthority(CertificateAuthorityConfiguration configCA, CrlConfiguration crlConfigure, CertificateAuthorityType CAtype, AWSACMPCA client) {
        RevocationConfiguration revokeConfig = new RevocationConfiguration();
        revokeConfig.setCrlConfiguration(crlConfigure);
        
        // Create the request object.
        CreateCertificateAuthorityRequest createCARequest = new CreateCertificateAuthorityRequest();
        createCARequest.withCertificateAuthorityConfiguration(configCA);
        createCARequest.withIdempotencyToken("123987");
        createCARequest.withCertificateAuthorityType(CAtype);
        createCARequest.withRevocationConfiguration(revokeConfig);
        
        // Create the private CA.
        CreateCertificateAuthorityResult createCAResult = null;
        try {
            createCAResult = client.createCertificateAuthority(createCARequest);
        } catch (InvalidArgsException ex) {
            throw ex;
        } catch (InvalidPolicyException ex) {
            throw ex;
        } catch (LimitExceededException ex) {
            throw ex;
        }

        // Retrieve the ARN of the private CA.
        String rootCAArn = createCAResult.getCertificateAuthorityArn();
        System.out.println("Product Attestation Authority (PAA) Arn: " + rootCAArn);
        
        return rootCAArn;
    }

    private static String GetCertificateAuthorityCsr(String rootCAArn, AWSACMPCA client) {

        // Create the CSR request object and set the CA ARN.
        GetCertificateAuthorityCsrRequest csrRequest = new GetCertificateAuthorityCsrRequest();
        csrRequest.withCertificateAuthorityArn(rootCAArn);

        // Create waiter to wait on successful creation of the CSR file.
        Waiter<GetCertificateAuthorityCsrRequest> getCSRWaiter = client.waiters().certificateAuthorityCSRCreated();
        try {
            getCSRWaiter.run(new WaiterParameters<>(csrRequest));
        } catch (WaiterUnrecoverableException e) {
            //Explicit short circuit when the recourse transitions into
            //an undesired state.
        } catch (WaiterTimedOutException e) {
            //Failed to transition into desired state even after polling.
        } catch (AWSACMPCAException e) {
            //Unexpected service exception.
        }

        // Retrieve the CSR.
        GetCertificateAuthorityCsrResult csrResult = null;
        try {
            csrResult = client.getCertificateAuthorityCsr(csrRequest);
        } catch (RequestInProgressException ex) {
            throw ex;
        } catch (ResourceNotFoundException ex) {
            throw ex;
        } catch (InvalidArnException ex) {
            throw ex;
        } catch (RequestFailedException ex) {
            throw ex;
        }

        // Retrieve and display the CSR;
        String csr = csrResult.getCsr();
        System.out.println(csr);

        return csr;
    }

    @SneakyThrows
    private static String generateAuthorityKeyIdentifier(final String csrPEM) {
        PKCS10CertificationRequest csr = getPKCS10CertificationRequest(csrPEM);
        SubjectPublicKeyInfo spki = csr.getSubjectPublicKeyInfo();
        
        JcaX509ExtensionUtils extensionUtils = new JcaX509ExtensionUtils();
        byte[] akiBytes = extensionUtils.createAuthorityKeyIdentifier(spki).getEncoded();

        return Base64.getEncoder().encodeToString(akiBytes);
    }

    @SneakyThrows
    private static PKCS10CertificationRequest getPKCS10CertificationRequest(final String csrPEM) {
        ByteArrayInputStream bais = new ByteArrayInputStream(csrPEM.getBytes());
        PemReader pemReader = new PemReader(new InputStreamReader(bais));
        PEMParser parser = new PEMParser(pemReader);
        Object o = parser.readObject();
        if (o instanceof PKCS10CertificationRequest) {
            return (PKCS10CertificationRequest) o;
        }
        return null;
    }

    private static String IssueCertificate(String rootCAArn, String csr, AWSACMPCA client) {

        // Create a certificate request:
        IssueCertificateRequest issueRequest = new IssueCertificateRequest();

        // Set the CA ARN.
        issueRequest.withCertificateAuthorityArn(rootCAArn);

        // Set the template ARN.
        issueRequest.withTemplateArn("arn:aws:acm-pca:::template/RootCACertificate_APIPassthrough/V1");

        ByteBuffer csrByteBuffer = stringToByteBuffer(csr);
        issueRequest.setCsr(csrByteBuffer);

        // Set the signing algorithm.
        issueRequest.withSigningAlgorithm(SigningAlgorithm.SHA256WITHECDSA);

        // Set the validity period for the certificate to be issued.
        Validity validity = new Validity();
        validity.withValue(3650L);
        validity.withType("DAYS");
        issueRequest.withValidity(validity);

        // Set the idempotency token.
        issueRequest.setIdempotencyToken("1234");

        // Generate Base64 encoded extension value for AuthorityKeyIdentifier
        String base64EncodedExtValue = generateAuthorityKeyIdentifier(csr);
  
        // Generate custom extension
        CustomExtension customExtension = new CustomExtension();
        customExtension.setObjectIdentifier("2.5.29.35"); // AuthorityKeyIdentifier Extension OID
        customExtension.setValue(base64EncodedExtValue);
  
        // Add custom extension to api-passthrough
        ApiPassthrough apiPassthrough = new ApiPassthrough();
        Extensions extensions = new Extensions();
        extensions.setCustomExtensions(Arrays.asList(customExtension));
        apiPassthrough.setExtensions(extensions);
        issueRequest.setApiPassthrough(apiPassthrough);

        // Issue the certificate.
        IssueCertificateResult issueResult = null;
        try {
            issueResult = client.issueCertificate(issueRequest);
        } catch (LimitExceededException ex) {
            throw ex;
        } catch (ResourceNotFoundException ex) {
            throw ex;
        } catch (InvalidStateException ex) {
            throw ex;
        } catch (InvalidArnException ex) {
            throw ex;
        } catch (InvalidArgsException ex) {
            throw ex;
        } catch (MalformedCSRException ex) {
            throw ex;
        }

        // Retrieve and display the certificate ARN.
        String rootCertificateArn = issueResult.getCertificateArn();
        System.out.println("Product Attestation Authority (PAA) Certificate Arn: " + rootCertificateArn);

        return rootCertificateArn;
    }
    
    private static String GetCertificate(String rootCertificateArn, String rootCAArn, AWSACMPCA client) {

        // Create a request object.
        GetCertificateRequest certificateRequest = new GetCertificateRequest();

        // Set the certificate ARN.
        certificateRequest.withCertificateArn(rootCertificateArn);

        // Set the certificate authority ARN.
        certificateRequest.withCertificateAuthorityArn(rootCAArn);
                
        // Create waiter to wait on successful creation of the certificate file.
        Waiter<GetCertificateRequest> getCertificateWaiter = client.waiters().certificateIssued();
        try {
            getCertificateWaiter.run(new WaiterParameters<>(certificateRequest));
        } catch (WaiterUnrecoverableException e) {
            //Explicit short circuit when the recourse transitions into
            //an undesired state.
        } catch (WaiterTimedOutException e) {
            //Failed to transition into desired state even after polling.
        } catch (AWSACMPCAException e) {
            //Unexpected service exception.
        }

        // Retrieve the certificate and certificate chain.
        GetCertificateResult certificateResult = null;
        try {
            certificateResult = client.getCertificate(certificateRequest);
        } catch (RequestInProgressException ex) {
            throw ex;
        } catch (RequestFailedException ex) {
            throw ex;
        } catch (ResourceNotFoundException ex) {
            throw ex;
        } catch (InvalidArnException ex) {
            throw ex;
        } catch (InvalidStateException ex) {
            throw ex;
        }

        // Get the certificate and certificate chain and display the result.
        String rootCertificate = certificateResult.getCertificate();
        System.out.println(rootCertificate);

        return rootCertificate;
    }

    private static void ImportCertificateAuthorityCertificate(String rootCertificate, String rootCAArn, AWSACMPCA client) {

        // Create the request object and set the signed certificate, chain and CA ARN.
        ImportCertificateAuthorityCertificateRequest importRequest =
            new ImportCertificateAuthorityCertificateRequest();

        ByteBuffer certByteBuffer = stringToByteBuffer(rootCertificate);
        importRequest.setCertificate(certByteBuffer);

        importRequest.setCertificateChain(null);

        // Set the certificate authority ARN.
        importRequest.withCertificateAuthorityArn(rootCAArn);

        // Import the certificate.
        try {
            client.importCertificateAuthorityCertificate(importRequest);
        } catch (CertificateMismatchException ex) {
            throw ex;
        } catch (MalformedCertificateException ex) {
            throw ex;
        } catch (InvalidArnException ex) {
            throw ex;
        } catch (ResourceNotFoundException ex) {
            throw ex;
        } catch (RequestInProgressException ex) {
            throw ex;
        } catch (ConcurrentModificationException ex) {
            throw ex;
        } catch (RequestFailedException ex) {
            throw ex;
        }

        System.out.println("Product Attestation Authority (PAA) certificate successfully imported.");
        System.out.println("Product Attestation Authority (PAA) activated successfully.");
    }
    
    private static ByteBuffer stringToByteBuffer(final String string) {
        if (Objects.isNull(string)) {
            return null;
        }
        byte[] bytes = string.getBytes(StandardCharsets.UTF_8);
        return ByteBuffer.wrap(bytes);
    }
}
```