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Node.js crypto.createHmac() Method

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  • Last Updated : 27 May, 2022
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The crypto.createHmac() method is used to create an Hmac object that uses the stated ‘algorithm’ and ‘key’. Syntax:

crypto.createHmac( algorithm, key, options )

Parameters: This method accept three parameters as mentioned above and described below:

  • algorithm: It is dependent on the accessible algorithms which are favored by the version of OpenSSL on the platform. It returns string. The examples are sha256, sha512, etc.
  • key: It is the HMAC key which is used to create the cryptographic HMAC hash. It returns string, Buffer, TypedArray, DataView, or KeyObject. And if it is a KeyObject, then its type must be secret.
  • options: It is optional parameter and used to control stream behavior. It returns an object.

Return Type: It returns Hmac object. Below examples illustrate the use of crypto.createHmac() method in Node.js: Example 1: 


// Node.js program to demonstrate the    
// crypto.createHmac() method
// Includes crypto module
const crypto = require('crypto');
// Defining key
const secret = 'GfG';
// Calling createHmac method
const hash = crypto.createHmac('sha256', secret)
                   // updating data
                   // Encoding to be used
// Displays output



Example 2: 


// Node.js program to demonstrate the    
// crypto.createHmac() method
// Defining myfile
const myfile = process.argv[1];
// Includes crypto and  fs module
const crypto = require('crypto');
const fs = require('fs');
// Creating Hmac
const creathmac = crypto.createHmac('sha1', 'CS-Portal!');
// Creating read stream
const readfile = fs.createReadStream(myfile);
readfile.on('readable', () => {
 // Calling read method to read data
  const data =;
  if (data)
    // Updating
    // Encoding and displaying filename
    console.log("The hmac object returns:",
    `${creathmac.digest('hex')} ${myfile}`);
console.log("Program done!");


Program done!
The hmac object returns: 4605d44703c2620fc2574c9a9216bd3267457324 /run_dir/interp.js


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