Web/API/SubtleCrypto/generateKey

Secure contextThis 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

const result = crypto.subtle.generateKey(algorithm, extractable, keyUsages);

Parameters

algorithm is a dictionary object defining the type of key to generate and providing extra algorithm-specific parameters.
- For RSASSA-PKCS1-v1_5, RSA-PSS, or RSA-OAEP: pass an RsaHashedKeyGenParams object.
- For ECDSA or ECDH: pass an EcKeyGenParams object.
- For HMAC: pass an HmacKeyGenParams object.
- For AES-CTR, AES-CBC, AES-GCM, or AES-KW: pass an AesKeyGenParams object.
extractable is a Boolean indicating whether it will be possible to export the key using SubtleCrypto.exportKey() or SubtleCrypto.wrapKey().
keyUsages is 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

result is 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: Raised when the result is a CryptoKey of type secret or private but keyUsages is empty.
SyntaxError: Raised when the result is a CryptoKeyPair and its privateKey.usages attribute is empty.

Examples

Note: You can [[../../../../../../../mdn.github.io/dom-examples/web-crypto/encrypt-decrypt/index|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 = 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 = 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 = 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 = window.crypto.subtle.generateKey(
  {
    name: "AES-GCM",
    length: 256
  },
  true,
  ["encrypt", "decrypt"]
);

Specifications

Specification	Status	Comment
Web Cryptography APIThe definition of 'SubtleCrypto.generateKey()' in that specification.	Recommendation	Initial definition.

Browser compatibility

Update compatibility data on GitHub

	Desktop						Mobile
	Chrome	Edge	Firefox	Internet Explorer	Opera	Safari	Android webview	Chrome for Android	Firefox for Android	Opera for Android	Safari on iOS	Samsung Internet
`generateKey`	Chrome Full support 37	Edge Partial support 12 Notes' Partial support 12 Notes' Notes' Not supported: RSA-PSS, ECDSA, ECDH. Notes' Not supported: AES-CTR.	Firefox Full support 34 Full support 34 No support 32 — 34 Disabled' Disabled' From version 32 until version 34 (exclusive): this feature is behind the `dom.webcrypto.enabled` preference (needs to be set to `true`). To change preferences in Firefox, visit about:config.	IE Partial support 11 Notes' Partial support 11 Notes' Notes' Returns `KeyOperation` instead of `Promise`	Opera Full support 24	Safari Full support 7	WebView Android Full support 37	Chrome Android Full support 37	Firefox Android Full support 34 Full support 34 No support 32 — 34 Disabled' Disabled' From version 32 until version 34 (exclusive): this feature is behind the `dom.webcrypto.enabled` preference (needs to be set to `true`). To change preferences in Firefox, visit about:config.	Opera Android Full support 24	Safari iOS Full support 7	Samsung Internet Android Full support 6.0

Legend

Full support: Full support
Partial support: Partial support
See implementation notes.': See implementation notes.
User must explicitly enable this feature.': User must explicitly enable this feature.