AES-CTR

W3 specification

Operations

Operation	Parameters	Result
generateKey	AesKeyGenParams	CryptoKey
importKey	None	CryptoKey
exportKey	None	JsonWebKey or BufferSource
encrypt	AesCtrParams	ArrayBuffer
decrypt	AesCtrParams	ArrayBuffer
wrapKey	AesCtrParams	ArrayBuffer
unwrapKey	AesCtrParams	CryptoKey

Generate key

const key = await crypto.subtle.generateKey(
  {
    name: "AES-CTR",
    length: 128, // 128, 192, or 256
  },
  false, // extractable
  ["encrypt", "decrypt", "wrapKey", "unwrapKey"], // key usages
);

Import key

const key = await crypto.subtle.importKey(
  "raw", // raw or jwk
  new Uint8Array([1, 2, 3, 4, 5, 6, 7, 8, 9, 0, 1, 2, 3, 4, 5, 6]), // raw data
  "AES-CTR",
  false, // extractable
  ["encrypt", "decrypt"],
);

Export key

const raw = await crypto.subtle.exportKey(
  "raw", // raw or jwk
  key,
);

Encrypt

const counter = crypto.getRandomValues(new Uint8Array(16));

const encData = await crypto.subtle.encrypt(
  {
    name: "AES-CTR",
    counter,     // BufferSource
    length: 128, // 1-128
  },
  key,  // AES key
  data, // BufferSource
);

Decrypt

const data = await crypto.subtle.decrypt(
  {
    name: "AES-CTR",
    counter,     // BufferSource
    length: 128, // 1-128
  },
  key,  // AES key
  encData, // BufferSource
);

Wrap key

const counter = crypto.getRandomValues(new Uint8Array(16));

const wrappedKey = await crypto.subtle.wrapKey(
  "pkcs8",   // raw, pkcs8, spki, or jwk
  anyKey,    // Crypto key
  key,       // AES key
  {
    name: "AES-CTR",
    counter,     // BufferSource
    length: 128, // 1-128
  },
);

Unwrap key

const unwrappedKey = await crypto.subtle.unwrapKey(
  "pkcs8",    // raw, pkcs8, spki, or jwk
  wrappedKey, // BufferSource
  key,        // AES key
  {
    name: "AES-CTR",
    counter,     // BufferSource
    length: 128, // 1-128
  },
  {
    name: "RSA-PSS",
    hash: "SHA-256",
  }
  false,      // extractable
  ["sign", "verify"],
);