类：Hmac

¥Class: Hmac

• 继承：<stream.Transform>

  ¥Extends: <stream.Transform>

Hmac 类是用于创建加密 HMAC 摘要的实用工具。它可以通过以下两种方式之一使用：

¥The Hmac class is a utility for creating cryptographic HMAC digests. It can be used in one of two ways:

• 作为可读可写的 流，写入数据以在可读端生成计算的 HMAC 摘要，或者

  ¥As a stream that is both readable and writable, where data is written to produce a computed HMAC digest on the readable side, or

• 使用 hmac.update() 和 hmac.digest() 方法生成计算出的 HMAC 摘要。

  ¥Using the hmac.update() and hmac.digest() methods to produce the computed HMAC digest.

crypto.createHmac() 方法用于创建 Hmac 实例。Hmac 对象不能直接使用 new 关键字创建。

¥The crypto.createHmac() method is used to create Hmac instances. Hmac objects are not to be created directly using the new keyword.

示例：使用 Hmac 对象作为流：

¥Example: Using Hmac objects as streams:

const {
  createHmac
} = await import('node:crypto');

const hmac = createHmac('sha256', 'a secret');

hmac.on('readable', () => {
  // Only one element is going to be produced by the
  // hash stream.
  const data = hmac.read();
  if (data) {
    console.log(data.toString('hex'));
    // Prints:
    //   7fd04df92f636fd450bc841c9418e5825c17f33ad9c87c518115a45971f7f77e
  }
});

hmac.write('some data to hash');
hmac.end();const {
  createHmac,
} = require('node:crypto');

const hmac = createHmac('sha256', 'a secret');

hmac.on('readable', () => {
  // Only one element is going to be produced by the
  // hash stream.
  const data = hmac.read();
  if (data) {
    console.log(data.toString('hex'));
    // Prints:
    //   7fd04df92f636fd450bc841c9418e5825c17f33ad9c87c518115a45971f7f77e
  }
});

hmac.write('some data to hash');
hmac.end();拷贝

示例：使用 Hmac 和管道流：

¥Example: Using Hmac and piped streams:

import { createReadStream } from 'node:fs';
import { stdout } from 'node:process';
const {
  createHmac
} = await import('node:crypto');

const hmac = createHmac('sha256', 'a secret');

const input = createReadStream('test.js');
input.pipe(hmac).pipe(stdout);const {
  createReadStream,
} = require('node:fs');
const {
  createHmac,
} = require('node:crypto');
const { stdout } = require('node:process');

const hmac = createHmac('sha256', 'a secret');

const input = createReadStream('test.js');
input.pipe(hmac).pipe(stdout);拷贝

示例：使用 hmac.update() 和 hmac.digest() 方法：

¥Example: Using the hmac.update() and hmac.digest() methods:

const {
  createHmac
} = await import('node:crypto');

const hmac = createHmac('sha256', 'a secret');

hmac.update('some data to hash');
console.log(hmac.digest('hex'));
// Prints:
//   7fd04df92f636fd450bc841c9418e5825c17f33ad9c87c518115a45971f7f77econst {
  createHmac,
} = require('node:crypto');

const hmac = createHmac('sha256', 'a secret');

hmac.update('some data to hash');
console.log(hmac.digest('hex'));
// Prints:
//   7fd04df92f636fd450bc841c9418e5825c17f33ad9c87c518115a45971f7f77e拷贝