类：Hmac

【Class: Hmac】

• 继承: <stream.Transform>

Hmac 类是用于创建加密 HMAC 摘要的工具类。它可以通过以下两种方式使用：

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

• 作为一个既可读又可写的 溪流，其中数据被写入以在可读端生成计算的 HMAC 摘要，或者
• 使用 hmac.update() 和 hmac.digest() 方法生成计算的 HMAC 摘要。

crypto.createHmac() 方法用于创建 Hmac 实例。Hmac 对象不应直接使用 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：将 Hmac 对象用作流：

【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