selfSigned.certificate,
        trusted.certificate,
      )
    assertThat(cleaner.clean(list(certB, certA), "hostname")).isEqualTo(
      list(certB, certA, trusted, selfSigned),
    )
    assertThat(cleaner.clean(list(certB, certA, trusted), "hostname")).isEqualTo(
      list(certB, certA, trusted, selfSigned),
    )
    assertThat(cleaner.clean(list(certB, certA, trusted, selfSigned), "hostname"))
      .isEqualTo(

   *
   *
   * The victim's gets a non-CA certificate signed by a CA, and pins the CA root and/or
   * intermediate. This is business as usual.
   *
   * ```
   *   pinnedRoot (trusted by CertificatePinner)
   *     -> pinnedIntermediate (trusted by CertificatePinner)
   *       -> realVictim
   * ```
   *
   * The attacker compromises a CA. They take the public key from an intermediate certificate

    /**
     * Configure the certificate chain to use when being authenticated. The first certificate is
     * the held certificate, further certificates are included in the handshake so the peer can
     * build a trusted path to a trusted root certificate.
     *
     * The chain should include all intermediate certificates but does not need the root certificate
     * that we expect to be known by the remote peer. The peer already has that certificate so

 * certificate is signed by the certificate that follows, and the last certificate is a trusted CA
 * certificate.
 *
 * Use of the chain cleaner is necessary to omit unexpected certificates that aren't relevant to
 * the TLS handshake and to extract the trusted CA certificate for the benefit of certificate
 * pinning.
 */
abstract class CertificateChainCleaner {

 *
 * <p>This interface is intended for internal use.</p>
 */
public interface DfsResolver {

    /**
     * Checks if a domain is trusted for DFS operations
     * @param tf the CIFS context
     * @param domain the domain name to check
     * @return whether the given domain is trusted
     * @throws CIFSException if the operation fails
     */
    boolean isTrustedDomain(CIFSContext tf, String domain) throws CIFSException;

      val toVerify = result[result.size - 1] as X509Certificate

      // If this cert has been signed by a trusted cert, use that. Add the trusted certificate to
      // the end of the chain unless it's already present. (That would happen if the first
      // certificate in the chain is itself a self-signed and trusted CA certificate.)
      val trustedCert = trustRootIndex.findByIssuerAndSignature(toVerify)
      if (trustedCert != null) {

-----------------------

The above example uses a self-signed certificate. This is convenient for testing but not
representative of real-world HTTPS deployment. To get closer to that we can use `HeldCertificate`
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

    /**
     * Cache of trusted domains for DFS resolution
     */
    protected CacheEntry _domains = null; /* aka trusted domains cache */
    /**
     * Cache of DFS referrals
     */
    protected CacheEntry referrals = null;

    /**
     * Gets the map of trusted domains for DFS resolution
     * @param auth the authentication credentials
     * @return a map of trusted domain names to domain controllers

		if err != nil {
			logger.Fatal(fmt.Errorf("invalid arguments passed, trusted user certificate authority public key file is not accessible: %v", err), "unable to start SFTP server")
		}

		globalSFTPTrustedCAPubkey, _, _, _, err = ssh.ParseAuthorizedKey(keyBytes)
		if err != nil {

******@****.***
******@****.***
hmac-sha2-256
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