val certificate = heldCertificate.certificate
    assertThat(certificate.getSubjectX500Principal().name, "self-signed")
      .isEqualTo(certificate.getIssuerX500Principal().name)
    assertThat(certificate.getIssuerX500Principal().name).matches(Regex("CN=[0-9a-f-]{36}"))
    assertThat(certificate.serialNumber).isEqualTo(BigInteger.ONE)
    assertThat(certificate.subjectAlternativeNames).isNull()

      + "0MC2Hb46TpSi125sC8KKfPog88Tk5c0NqMuRkrF8hey1FGlmDoLnzc7ILaZRfyHB\n"
      + "NVOFBkpdn627G190\n"
      + "-----END CERTIFICATE-----\n");

  final X509Certificate entrustRootCertificateAuthority = Certificates.decodeCertificatePem(""
      + "-----BEGIN CERTIFICATE-----\n"
      + "MIIEkTCCA3mgAwIBAgIERWtQVDANBgkqhkiG9w0BAQUFADCBsDELMAkGA1UEBhMC\n"

    builder = builder.heldCertificate(heldCertificate, heldCertificate.certificate())
    builder = builder.addTrustedCertificate(heldCertificate.certificate())
  }

  @Test @Disabled
  fun heldCertificate() {
    val heldCertificate: HeldCertificate = HeldCertificate.Builder().build()
    val certificate: X509Certificate = heldCertificate.certificate()
    val keyPair: KeyPair = heldCertificate.keyPair()
  }

    val certificate: X509Certificate = heldCertificate.certificate
    val certificatePinner: CertificatePinner = CertificatePinner.Builder().build()
    val certificates: List<Certificate> = listOf()
    certificatePinner.check("", listOf(certificate))
    certificatePinner.check("", arrayOf<Certificate>(certificate, certificate).toList())
    val pin: String = CertificatePinner.pin(certificate)

    /**
     * Returns the SHA-256 of `certificate`'s public key.
     *
     * In OkHttp 3.1.2 and earlier, this returned a SHA-1 hash of the public key. Both types are
     * supported, but SHA-256 is preferred.
     */
    @JvmStatic
    fun pin(certificate: Certificate): String {
      require(certificate is X509Certificate) { "Certificate pinning requires X509 certificates" }

  /** Can still coalesce when pinning is used if pins match.  */
  @Test
  fun coalescesWhenCertificatePinsMatch() {
    val pinner =
      CertificatePinner
        .Builder()
        .add("san.com", pin(certificate.certificate))
        .build()
    client = client.newBuilder().certificatePinner(pinner).build()
    server.enqueue(MockResponse())
    server.enqueue(MockResponse())

credentials via the STS API. It can authenticate via a client certificate and obtain a access/secret key pair as well as a session token. These credentials are associated to an S3 policy at the MinIO server.

In case of certificate-based authentication, MinIO has to map the client-provided certificate to an S3 policy. MinIO does this via the subject common name field of the X.509 certificate. So, MinIO will associate a certificate with a subject `CN = foobar` to a S3 policy named `foobar`....

        )
      },
    )

  /**
   * ```
   * Certificate ::= SEQUENCE  {
   *   tbsCertificate       TBSCertificate,
   *   signatureAlgorithm   AlgorithmIdentifier,
   *   signatureValue       BIT STRING
   * }
   * ```
   */
  internal val certificate: BasicDerAdapter<Certificate> =
    Adapters.sequence(
      "Certificate",
      tbsCertificate,
      algorithmIdentifier,

	}

	cert, ok := clientKey.(*ssh.Certificate)
	if !ok {
		return errSftpPublicKeyWithoutCert
	}

	// ssh.CheckCert called by ssh.Authenticate accepts certificates
	// with empty principles list so we block those in here.
	if len(cert.ValidPrincipals) == 0 {
		return errSftpCertWithoutPrincipals
	}

	// Verify that certificate provided by user is issued by trusted CA,

hmac-sha2-512
hmac-sha1
hmac-sha1-96
```

### Certificate-based authentication

`--sftp=trusted-user-ca-key=...` specifies a file containing public key of certificate authority that is trusted
to sign user certificates for authentication.

Implementation is identical with "TrustedUserCAKeys" setting in OpenSSH server with exception that only one CA
key can be defined.