Important: This documentation is about an older version. It's relevant only to the release noted, many of the features and functions have been updated or replaced. Please view the current version.

JavaScript API

k6/experimental

webcrypto

Open source

webcrypto

Caution
This is an experimental module.

While we intend to keep experimental modules as stable as possible, we may need to introduce breaking changes. This could happen at future k6 releases until the module becomes fully stable and graduates as a k6 core module. For more information, refer to the extension graduation process.

Experimental modules maintain a high level of stability and follow regular maintenance and security measures. Feel free to open an issue if you have any feedback or suggestions.

With this experimental module, you can use the WebCrypto API in your k6 scripts. However, note that this API is not yet fully implemented and some algorithms and features might still be missing.

The Web Crypto API is a JavaScript API for performing cryptographic operations such as encryption, decryption, digital signature generation and verification, and key generation and management. It provides a standard interface to access cryptographic functionality, which can help ensure that cryptographic operations are performed correctly and securely.

API

The module exports a top-level crypto object with the following properties and methods:

Interface/Function	Description
getRandomValues	Fills the passed `TypedArray` with cryptographically sound random values.
randomUUID	Returns a randomly generated, 36 character long v4 UUID.
subtle	The SubtleCrypto interface provides access to common cryptographic primitives, such as hashing, signing, encryption, or decryption.

Example

import { crypto } from 'k6/experimental/webcrypto';

export default async function () {
  const plaintext = stringToArrayBuffer('Hello, World!');

  /**
   * Generate a symmetric key using the AES-CBC algorithm.
   */
  const key = await crypto.subtle.generateKey(
    {
      name: 'AES-CBC',
      length: 256,
    },
    true,
    ['encrypt', 'decrypt']
  );

  /**
   * Encrypt the plaintext using the AES-CBC key with
   * have generated.
   */
  const iv = crypto.getRandomValues(new Uint8Array(16));
  const ciphertext = await crypto.subtle.encrypt(
    {
      name: 'AES-CBC',
      iv: iv,
    },
    key,
    plaintext
  );

  /**
   * Decrypt the ciphertext using the same key to verify
   * that the resulting plaintext is the same as the original.
   */
  const deciphered = await crypto.subtle.decrypt(
    {
      name: 'AES-CBC',
      iv: iv,
    },
    key,
    ciphertext
  );

  console.log(
    'deciphered text == original plaintext: ',
    arrayBufferToHex(deciphered) === arrayBufferToHex(plaintext)
  );
}

function arrayBufferToHex(buffer) {
  return [...new Uint8Array(buffer)].map((x) => x.toString(16).padStart(2, '0')).join('');
}

function stringToArrayBuffer(str) {
  const buf = new ArrayBuffer(str.length * 2); // 2 bytes for each char
  const bufView = new Uint16Array(buf);
  for (let i = 0, strLen = str.length; i < strLen; i++) {
    bufView[i] = str.charCodeAt(i);
  }
  return buf;
}