val data = CertificateAdapters.certificate.toDer(this)
    try {
      val certificateFactory = CertificateFactory.getInstance("X.509")
      val certificates = certificateFactory.generateCertificates(Buffer().write(data).inputStream())
      return certificates.single() as X509Certificate
    } catch (e: NoSuchElementException) {
      throw IllegalArgumentException("failed to decode certificate", e)
    } catch (e: IllegalArgumentException) {

import okhttp3.OkHttpClient;
import okhttp3.Protocol;
import okhttp3.Request;
import okhttp3.Response;
import org.junit.Test;
import org.junit.runner.RunWith;

import java.io.IOException;
import java.security.cert.Certificate;
import java.security.cert.X509Certificate;

import static org.junit.Assert.assertEquals;
import static org.junit.Assert.assertTrue;

/**
 * Simple test adaptable to show a failure in older versions of OkHttp

import okhttp3.mockwebserver.MockResponse;
import okhttp3.mockwebserver.MockWebServer;
import okhttp3.tls.HandshakeCertificates;
import okhttp3.tls.HeldCertificate;

/**
 * Create an HTTPS server with a self-signed certificate that OkHttp trusts.
 */
public class HttpsServer {
  public void run() throws Exception {
    HeldCertificate localhostCertificate = new HeldCertificate.Builder()
        .addSubjectAlternativeName("localhost")

        .build()
    val handshakeCertificates =
      HandshakeCertificates.Builder()
        .heldCertificate(heldCertificate)
        .addTrustedCertificate(heldCertificate.certificate)
        .build()
    server.useHttps(handshakeCertificates.sslSocketFactory())

    val dns =
      Dns {
        Dns.SYSTEM.lookup(server.hostName)
      }

    val client =

        .build()
    val handshakeCertificates =
      HandshakeCertificates.Builder()
        .heldCertificate(heldCertificate)
        .addTrustedCertificate(heldCertificate.certificate)
        .build()

    client =
      client.newBuilder()
        .sslSocketFactory(
          handshakeCertificates.sslSocketFactory(),
          handshakeCertificates.trustManager,
        )

 * limitations under the License.
 */
package okhttp3.tls.internal.der

import okio.Buffer
import okio.ByteString

/**
 * Encode and decode a model object like a [Long] or [Certificate] as DER bytes.
 */
internal interface DerAdapter<T> {
  /** Returns true if this adapter can read [header] in a choice. */
  fun matches(header: DerHeader): Boolean

  /**
   * Returns a value from this adapter.

    throw IllegalArgumentException("failed to decode certificate", nsee)
  } catch (iae: IllegalArgumentException) {
    throw IllegalArgumentException("failed to decode certificate", iae)
  } catch (e: GeneralSecurityException) {
    throw IllegalArgumentException("failed to decode certificate", e)
  }
}

/**
 * Returns the certificate encoded in [PEM format][rfc_7468].
 *
 * [rfc_7468]: https://tools.ietf.org/html/rfc7468
 */

    }
  }

  fun verify(
    host: String,
    certificate: X509Certificate,
  ): Boolean {
    return when {
      host.canParseAsIpAddress() -> verifyIpAddress(host, certificate)
      else -> verifyHostname(host, certificate)
    }
  }

  /** Returns true if [certificate] matches [ipAddress]. */
  private fun verifyIpAddress(
    ipAddress: String,
    certificate: X509Certificate,
  ): Boolean {

    assertThat(listOf(clientCertificate.certificate, clientIntermediate.certificate))
      .isEqualTo(serverHandshake.peerCertificates)
    assertThat(listOf(serverCertificate.certificate, serverIntermediate.certificate))
      .isEqualTo(serverHandshake.localCertificates)
    val clientHandshake = clientHandshakeFuture.get()
    assertThat(listOf(serverCertificate.certificate, serverIntermediate.certificate))

      + "jaA9VEhgdaVhxBsT2qzUNDsXlOzGsliznDfoqETb\n"
      + "-----END CERTIFICATE-----\n";

    X509Certificate certificate =
        Certificates.decodeCertificatePem(certificateString);

    assertEquals(certificateString, Certificates.certificatePem(certificate));
  }