SubtleCrypto.generateKey()

Secure context: This feature is available only in secure contexts (HTTPS), in some or all supporting browsers.

Use the generateKey() method of the SubtleCrypto interface to generate a new key (for symmetric algorithms) or key pair (for public-key algorithms).

Syntax

generateKey(algorithm, extractable, keyUsages)

Parameters

algorithm

An object defining the type of key to generate and providing extra algorithm-specific parameters.

extractable

A boolean value indicating whether it will be possible to export the key using SubtleCrypto.exportKey() or SubtleCrypto.wrapKey().

keyUsages

An Array indicating what can be done with the newly generated key. Possible values for array elements are:

  • encrypt: The key may be used to encrypt messages.
  • decrypt: The key may be used to decrypt messages.
  • sign: The key may be used to sign messages.
  • verify: The key may be used to verify signatures.
  • deriveKey: The key may be used in deriving a new key.
  • deriveBits: The key may be used in deriving bits.
  • wrapKey: The key may be used to wrap a key.
  • unwrapKey: The key may be used to unwrap a key.

Return value

A Promise that fulfills with a CryptoKey (for symmetric algorithms) or a CryptoKeyPair (for public-key algorithms).

Exceptions

The promise is rejected when the following exception is encountered:

SyntaxError DOMException

Raised when the result is a CryptoKey of type secret or private but keyUsages is empty.

SyntaxError DOMException

Raised when the result is a CryptoKeyPair and its privateKey.usages attribute is empty.

Examples

Note: You can try the working examples on GitHub.

RSA key pair generation

This code generates an RSA-OAEP encryption key pair. See the complete code on GitHub.

let keyPair = await window.crypto.subtle.generateKey(
  {
    name: "RSA-OAEP",
    modulusLength: 4096,
    publicExponent: new Uint8Array([1, 0, 1]),
    hash: "SHA-256"
  },
  true,
  ["encrypt", "decrypt"]
);

Elliptic curve key pair generation

This code generates an ECDSA signing key pair. See the complete code on GitHub.

let keyPair = await window.crypto.subtle.generateKey(
  {
    name: "ECDSA",
    namedCurve: "P-384"
  },
  true,
  ["sign", "verify"]
);

HMAC key generation

This code generates an HMAC signing key. See the complete code on GitHub.

let key = await window.crypto.subtle.generateKey(
  {
    name: "HMAC",
    hash: {name: "SHA-512"}
  },
  true,
  ["sign", "verify"]
);

AES key generation

This code generates an AES-GCM encryption key. See the complete code on GitHub.

let key = await window.crypto.subtle.generateKey(
  {
    name: "AES-GCM",
    length: 256
  },
  true,
  ["encrypt", "decrypt"]
);

Specifications

Specification
Web Cryptography API
# SubtleCrypto-method-generateKey

Browser compatibility

BCD tables only load in the browser

See also