#### A "professional" attack

Of course, the attackers would not try all this by hand, they would write a program to do it, possibly with thousands or millions of tests per second. And would get just one extra correct letter at a time.

    proxySelector.proxies.add(Proxy.NO_PROXY)
    server.shutdown()

    client =
      client.newBuilder()
        .proxySelector(proxySelector)
        .readTimeout(Duration.ofMillis(100))
        .connectTimeout(Duration.ofMillis(100))
        .build()

    val request = Request(server.url("/"))
    assertFailsWith<IOException> {
      client.newCall(request).execute()
    }.also { expected ->

  fun exhaustResponse() =
    apply {
      actions += { stream -> stream.responseBody.close() }
    }

  fun sleep(
    duration: Long,
    unit: TimeUnit,
  ) = apply {
    actions += { Thread.sleep(unit.toMillis(duration)) }
  }

  override fun handle(stream: Stream) {
    val task = serviceStreamTask(stream)
    results.add(task)
    task.run()
  }

    call: Call,
    cachedResponse: Response,
  ) {
    logWithTime("cacheConditionalHit: $cachedResponse")
  }

  private fun logWithTime(message: String) {
    val timeMs = TimeUnit.NANOSECONDS.toMillis(System.nanoTime() - startNs)
    logger.log("[$timeMs ms] $message")
  }

  open class Factory
    @JvmOverloads
    constructor(

    lastTimestampNs = result.timestampNs

    if (eventClass != null) {
      assertThat(result).isInstanceOf(eventClass)
    }

    if (elapsedMs != -1L) {
      assertThat(
        TimeUnit.NANOSECONDS.toMillis(actualElapsedNs)
          .toDouble(),
      )
        .isCloseTo(elapsedMs.toDouble(), 100.0)
    }

    return result
  }

  fun recordedEventTypes() = eventSequence.map { it.name }

    server!!.enqueue(
      MockResponse.Builder()
        .headersDelay(2, TimeUnit.SECONDS)
        .build(),
    )
    client =
      client.newBuilder()
        .readTimeout(Duration.ofMillis(250))
        .build()
    val call =
      client.newCall(
        Request.Builder()
          .url(server!!.url("/"))
          .build(),
      )
    assertFailsWith<IOException> {

---

Common examples of CPU bound operations are things that require complex math processing.

For example:

* **Audio** or **image processing**.
* **Computer vision**: an image is composed of millions of pixels, each pixel has 3 values / colors, processing that normally requires computing something on those pixels, all at the same time.

 * example, the Unicode trademark sign (™) could be confused for the letters "TM" in
 * `http://ho™ail.com`. To mitigate this, the single character (™) maps to the string (tm). There
 * is similar policy for all of the 1.1 million Unicode code points. Note that some code points such
 * as "\ud83c\udf69" are not mapped and cannot be used in a hostname.
 *
 * [Punycode](http://ietf.org/rfc/rfc3492.txt) converts a Unicode string to an ASCII string to make

    server.enqueue(
      MockResponse.Builder()
        .headersDelay(2, TimeUnit.SECONDS)
        .build(),
    )
    client =
      client.newBuilder()
        .readTimeout(Duration.ofMillis(250))
        .build()
    val call =
      client.newCall(
        Request.Builder()
          .url(server.url("/"))
          .build(),
      )
    assertFailsWith<IOException> {

        .build()
    clientCert =
      HeldCertificate.Builder()
        .signedBy(clientIntermediateCa)
        .serialNumber(4L)
        .commonName("Jethro Willis")
        .addSubjectAlternativeName("jethrowillis.com")
        .build()
  }

  @Test
  fun clientAuthForWants() {
    val client = buildClient(clientCert, clientIntermediateCa.certificate)