*/
  public static final int BYTES = Double.SIZE / Byte.SIZE;

  /**
   * Returns a hash code for {@code value}; equal to the result of invoking {@code ((Double)
   * value).hashCode()}.
   *
   * <p><b>Java 8+ users:</b> use {@link Double#hashCode(double)} instead.
   *
   * @param value a primitive {@code double} value
   * @return a hash code for the value
   */
  public static int hashCode(double value) {

If it is allowed, we will forward to the target destination.

#### Hairpin

In the case that the destination has a waypoint, that waypoint must have been bypassed to reach the inbound passthrough codepath.
How we handle this is [under discussion](https://docs.google.com/document/d/1uM1c3zzoehiijh1ZpZuJ1-SzuVVupenv8r5yuCaFshs/edit#heading=h.dwbqvwmg6ud3).

### Inbound

    return new Equivalence<T>() {
      @Override
      protected boolean doEquivalent(T a, T b) {
        return false;
      }

      @Override
      protected int doHash(T t) {
        return 0;
      }

      final String string = paramString(Equivalence.class, generateInt());

      @Override
      public String toString() {
        return string;
      }

// along with this program.  If not, see <http://www.gnu.org/licenses/>.

package cmd

import (
	"context"
	"encoding/binary"
	"errors"
	"fmt"
	"hash/crc32"
	"math/rand"
	"net/http"
	"reflect"
	"strings"
	"sync"
	"time"

	"github.com/dchest/siphash"
	"github.com/google/uuid"
	"github.com/minio/madmin-go/v3"
	"github.com/minio/minio-go/v7/pkg/set"

- cloud.google.com/go/datastore: v1.0.0
- cloud.google.com/go/pubsub: v1.0.1
- cloud.google.com/go/storage: v1.0.0
- dmitri.shuralyov.com/gpu/mtl: 666a987
- github.com/cespare/xxhash/v2: [v2.1.1](https://github.com/cespare/xxhash/v2/tree/v2.1.1)
- github.com/checkpoint-restore/go-criu/v4: [v4.0.2](https://github.com/checkpoint-restore/go-criu/v4/tree/v4.0.2)

              <annotation>com.google.common.collect.testing.testers.IgnoreJRERequirement</annotation>
              <annotation>com.google.common.hash.IgnoreJRERequirement</annotation>
              <annotation>com.google.common.io.IgnoreJRERequirement</annotation>
              <annotation>com.google.common.math.IgnoreJRERequirement</annotation>

              <annotation>com.google.common.collect.testing.testers.IgnoreJRERequirement</annotation>
              <annotation>com.google.common.hash.IgnoreJRERequirement</annotation>
              <annotation>com.google.common.io.IgnoreJRERequirement</annotation>
              <annotation>com.google.common.math.IgnoreJRERequirement</annotation>

# OAuth2 实现密码哈希与 Bearer  JWT 令牌验证

至此，我们已经编写了所有安全流，本章学习如何使用 <abbr title="JSON Web Tokens">JWT</abbr> 令牌（Token）和安全密码哈希（Hash）实现真正的安全机制。

本章的示例代码真正实现了在应用的数据库中保存哈希密码等功能。

接下来，我们紧接上一章，继续完善安全机制。

## JWT 简介

JWT 即**JSON 网络令牌**（JSON Web Tokens）。

JWT 是一种将 JSON 对象编码为没有空格，且难以理解的长字符串的标准。JWT 的内容如下所示：

```

pkg hash/crc64, const ISO ideal-int
pkg hash/crc64, const Size ideal-int
pkg hash/crc64, func Checksum([]uint8, *Table) uint64
pkg hash/crc64, func MakeTable(uint64) *Table
pkg hash/crc64, func New(*Table) hash.Hash64
pkg hash/crc64, func Update(uint64, *Table, []uint8) uint64
pkg hash/crc64, type Table [256]uint64
pkg hash/fnv, func New32() hash.Hash32
pkg hash/fnv, func New32a() hash.Hash32
pkg hash/fnv, func New64() hash.Hash64

 *   <li>The performance of using the associated {@code Builder} class can be assumed to be no
 *       worse, and possibly better, than creating a mutable collection and copying it.
 *   <li>Implementations generally do not cache hash codes. If your element or key type has a slow
 *       {@code hashCode} implementation, it should cache it itself.
 * </ul>
 *
 * <h4>Example usage</h4>
 *
 * <pre>{@code
 * class Foo {