## Proxy implementation

In its initial implementations, the ztunnel was actually implemented in 3 different ways: a bespoke Rust implementation, a bespoke Go implementation, and in Envoy.

In the end, [after evaluation](https://docs.google.com/document/d/1c2123cKuYsBDpIon9FFdctWTUIMFweSjgwG7r8l3818/edit), the decision was to move forward with a Rust implementation.

// that they have access to.
//
// It can be optionally associated with a particular assigner, in which case it
// contains one valid set of trust anchors for that signer. Signers may have
// multiple associated ClusterTrustBundles; each is an independent set of trust
// anchors for that signer. Admission control is used to enforce that only users
// with permissions on the signer can create or modify the corresponding bundle.

    /**
     * No trust - no information about status.
     */
    public static final ArtifactStatus NONE = new ArtifactStatus("none", 0);

    /**
     * No trust - information was generated with defaults.
     */
    public static final ArtifactStatus GENERATED = new ArtifactStatus("generated", 1);

    /**
     * Low trust - was converted from the Maven 1.x repository.
     */

		secretItemColumns = append(secretItemColumns, "TRUST DOMAIN")
	}
	tw := new(tabwriter.Writer).Init(w.w, 0, 5, 5, ' ', 0)
	fmt.Fprintln(tw, strings.Join(secretItemColumns, "\t"))
	for _, s := range secrets {
		if includeConfigType {
			s.Name = fmt.Sprintf("secret/%s", s.Name)
		}
		// If all secrets have a trust domain, we are probably dealing with trust domain federation, so print trust domains.

import okhttp3.internal.toImmutableList
import okhttp3.tls.internal.TlsUtil.newKeyManager
import okhttp3.tls.internal.TlsUtil.newTrustManager

/**
 * Certificates to identify which peers to trust and also to earn the trust of those peers in kind.
 * Client and server exchange these certificates during the handshake phase of a TLS connection.
 *
 * ### Server Authentication
 *

MockWebServer server = new MockWebServer();
server.useHttps(serverCertificates.sslSocketFactory(), false);
```

`HandshakeCertificates` also works for clients where its job is to define which root certificates
to trust. In this simplified example we trust the server's self-signed certificate:

```java
HandshakeCertificates clientCertificates = new HandshakeCertificates.Builder()
    .addTrustedCertificate(localhostCertificate.certificate())
    .build();

 *
 * Supported on OpenJDK 8 via the JettyALPN-boot library or Conscrypt.
 *
 * Supported on OpenJDK 9+ via SSLParameters and SSLSocket features.
 *
 * ### Trust Manager Extraction
 *
 * Supported on Android 2.3+ and OpenJDK 7+. There are no public APIs to recover the trust
 * manager that was used to create an [SSLSocketFactory].
 *
 * Not supported by choice on JDK9+ due to access checks.
 *
 * ### Android Cleartext Permit Detection

object TlsUtil {
  val password = "password".toCharArray()

  private val localhost: HandshakeCertificates by lazy {
    // Generate a self-signed cert for the server to serve and the client to trust.
    val heldCertificate =
      HeldCertificate.Builder()
        .commonName("localhost")
        .addSubjectAlternativeName("localhost")
        .addSubjectAlternativeName("localhost.localdomain")
        .build()

  private val sslExcludeFilter =
    Regex(
      buildString {
        append("^(?:")
        append(
          listOf(
            "Inaccessible trust store",
            "trustStore is",
            "Reload the trust store",
            "Reload trust certs",
            "Reloaded",
            "adding as trusted certificates",
            "Ignore disabled cipher suite",
            "Ignore unsupported cipher suite",

  /**
   * Returns a cleaned chain for [chain].
   *
   * This method throws if the complete chain to a trusted CA certificate cannot be constructed.
   * 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,