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()
  }

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.

	}

	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,

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")

  }

  /** 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())

        .build()

    client.newCall(request).execute().use { response ->
      if (!response.isSuccessful) throw IOException("Unexpected code $response")

      for (certificate in response.handshake!!.peerCertificates) {
        println(CertificatePinner.pin(certificate))
      }
    }
  }
}

fun main() {
  CertificatePinning().run()

## Version 4.2.0

_2019-09-10_

 *  New: API to decode a certificate and private key to create a `HeldCertificate`. This accepts a
    string containing both a certificate and PKCS #8-encoded private key.

    ```kotlin
    val heldCertificate = HeldCertificate.decode("""
        |-----BEGIN CERTIFICATE-----
        |MIIBYTCCAQegAwIBAgIBKjAKBggqhkjOPQQDAjApMRQwEgYDVQQLEwtlbmdpbmVl

setting](/pkg/runtime#hdr-Environment_Variable). These stack traces have
non-standard semantics, see setting documentation for details.

Go 1.22 added a new [`crypto/x509.Certificate`](/pkg/crypto/x509/#Certificate)
field, [`Policies`](/pkg/crypto/x509/#Certificate.Policies), which supports
certificate policy OIDs with components larger than 31 bits. By default this
field is only used during parsing, when it is populated with policy OIDs, but

// error returned in SFTP when user used public key without certificate
var errSftpPublicKeyWithoutCert = errors.New("public key authentication without certificate is not accepted")

// error returned in SFTP when user used certificate which does not contain principal(s)
var errSftpCertWithoutPrincipals = errors.New("certificates without principal(s) are not accepted")

		}
		buf.WriteString("\n")
	}
	return values
}

// CertificateText returns a human-readable string representation
// of the certificate cert. The format is similar to the OpenSSL
// way of printing certificates (not identical).
func CertificateText(cert *x509.Certificate) string {
	var buf strings.Builder

	buf.WriteString(color.Blue("\nCertificate:\n"))
	if cert.SignatureAlgorithm != x509.UnknownSignatureAlgorithm {