AesCtrParams

The AesCtrParams object represents the object that should be passed as the algorithm parameter into the encrypt and decrypt operation when using the AES-CTR algorithm.

For more details, head to the MDN Web Crypto API documentation on AES-CTR.

Properties

Property	Type	Description
name	`string`	Should be set to `AES-CTR`.
counter	`ArrayBuffer`, `TypedArray`, or `DataView`	The initial value of the counter block. This must be 16-bytes long, like the AES block size.
length	`number`	The number of bits in the counter block that are used for the actual counter. It is recommended to use 64 (half of the counter block).

Example

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

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

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

  /**
   * Encrypt the plaintext using the AES-CTR key with
   * have generated.
   */
  const ciphertext = await crypto.subtle.encrypt(
    {
      name: 'AES-CTR',
      counter: crypto.getRandomValues(new Uint8Array(16)),
      length: 128,
    },
    key,
    plaintext
  );
}

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;
}