Web Crypto API Digital Signature Using PBKDF2 and HMAC

by Anish

Posted on Tuesday september 25, 2018


This sample chapter extracted from the book, Cryptography for JavaScript Developers.


In this example we are going to produce the digital signature of the message by using pbkdf2 key derivation function, and then sign the message from the derived key using HMAC, then we are going to verify the message


PBKDF2,HMAC Digital Signature Demo

This is the web cryptography api example of producing digital signature of the message

Iteration:
Password:
Input Message:
Singed Message:
PBKDF2 Derived Key (Hex):
Randow Salt (Hex) :

pbkdf2,hmac Javascript example of using webcrypto api

The first step is to derive the key from the user supplied password,

window.crypto.subtle.importKey(
      'raw', 
      passphraseKey, 
      {name: 'PBKDF2'}, 
      false, 
      ['deriveBits', 'deriveKey']
    ).then(function(key) {
    
      return window.crypto.subtle.deriveKey(
        { "name": 'PBKDF2',
          "salt": saltBuffer,
          "iterations": iterations,
          "hash": 'SHA-256'
        },
        key,
        { "name": 'HMAC', hash: {name: "SHA-256"} },
        true,
        [ "sign","verify"]
      )
    }).then(function (webKey) {
      publicKey=webKey

Once the key is derived, now we are signing the message, using this derived key

window.crypto.subtle.sign(
          {
            name: "HMAC"
          },
          webKey,
          asciiToUint8Array(plainText) //ArrayBuffer of data we want to sign
        )
        .then(function(signature){
          document.getElementById("signature").value= bytesToHexString(signature)
        })
        .catch(function(err){
          console.error(err);
        });
    
        return crypto.subtle.exportKey("raw", webKey);
    
    }).then(function (buffer) {
    
        document.getElementById("key").value= bytesToHexString(buffer);
        document.getElementById("salt").value= bytesToHexString(saltBuffer);
    });

Signature Verification To verify the signature of the message, pass the pbdkf2 crypto key,signature and the plain text message

window.crypto.subtle.verify({
                    name: "HMAC",
                },
                publicKey,
                hexStringToUint8Array(signature),
                asciiToUint8Array(plainText)
            )
            .then(function(decrypted) {
                alert("Verified   " + decrypted);
            })
            .catch(function(err) {
                console.error(err);
            });

Download the sample code here
Next Reading Web Crypto API PBKDF2 Generate Password

Thanku for reading !!! Give a Share for Support

Asking for donation sound bad to me, so i'm raising fund from by offering all my Nine book for just $9



python Cryptography Topics
Topics
For Coffee/ Beer/ Amazon Bill and further development of the project Support by Purchasing, The Modern Cryptography CookBook for Just $9 Coupon Price

Kubernetes for DevOps

Hello Dockerfile

Cryptography for Python Developers

Cryptography for JavaScript Developers

Go lang ryptography for Developers

Here