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) {

    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
 */

     * certificate can sign other certificates (but those certificates cannot themselves sign
     * certificates). Set this to 1 so this certificate can sign intermediate certificates that can
     * themselves sign certificates. Add one for each additional layer of intermediates to permit.
     */
    fun certificateAuthority(maxIntermediateCas: Int) =
      apply {

 *
 *  * The client's handshake certificates must have a [held certificate][HeldCertificate] (a
 *    certificate and its private key). The client must also have a (possibly-empty) chain of
 *    intermediate certificates to establish trust from a root certificate to the client's
 *    certificate. The root certificate is not included in this chain.
 *  * The server's handshake certificates must include a set of trusted root certificates. They

    assertThat(cleaner.clean(certificates, "hostname")).isEqualTo(certificates)
    assertThat(cleaner.clean(certificates.subList(0, 9), "hostname")).isEqualTo(
      certificates,
    )
  }

  @Test
  fun chainTooLong() {
    val heldCertificates = chainOfLength(11)
    val certificates: MutableList<Certificate> = ArrayList()
    for (heldCertificate in heldCertificates) {
      certificates.add(heldCertificate.certificate)

to generate a trusted root certificate, an intermediate certificate, and a server certificate.
We use `certificateAuthority(int)` to create certificates that can sign other certificates. The
int specifies how many intermediate certificates are allowed beneath it in the chain.

```java
HeldCertificate rootCertificate = new HeldCertificate.Builder()
    .certificateAuthority(1)
    .build();

  //  5. Expiration/certificate lifetime: whether it is fixed by the signer, configurable by the admin.
  //  6. Whether or not requests for CA certificates are allowed.
  optional string signerName = 7;

  // expirationSeconds is the requested duration of validity of the issued
  // certificate. The certificate signer may issue a certificate with a different

    }

    // Should not be pinned:
    certificatePinner.check("uk", listOf(certB1.certificate))
    certificatePinner.check("co.uk", listOf(certB1.certificate))
    certificatePinner.check("anotherexample.co.uk", listOf(certB1.certificate))
    certificatePinner.check("foo.anotherexample.co.uk", listOf(certB1.certificate))
  }

  @Test
  fun testBadPin() {

   * This is unexpected unless the trust root index in this class has a different trust manager than
   * what was used to establish [chain].
   */
  @Throws(SSLPeerUnverifiedException::class)
  override fun clean(
    chain: List<Certificate>,
    hostname: String,
  ): List<Certificate> {
    val queue: Deque<Certificate> = ArrayDeque(chain)

    // Add a bad intermediate CA and have that issue a rogue certificate for localhost. Prepare
    // an SSL context for an attacking webserver. It includes both these rogue certificates plus the
    // trusted good certificate above. The attack is that by including the good certificate in the
    // chain, we may trick the certificate pinner into accepting the rouge certificate.
    val compromisedIntermediateCa =
      HeldCertificate.Builder()