CryptoKey: usages property
Baseline
Widely available
This feature is well established and works across many devices and browser versions. It’s been available across browsers since July 2015.
Secure context: This feature is available only in secure contexts (HTTPS), in some or all supporting browsers.
Note: This feature is available in Web Workers.
The read-only usages property of the CryptoKey interface indicates what can be done with the key.
Value
An Array of strings from the following list:
"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.
Examples
js
const rawKey = window.crypto.getRandomValues(new Uint8Array(16));
// Import an AES secret key from an ArrayBuffer containing the raw bytes.
// Takes an ArrayBuffer string containing the bytes, and returns a Promise
// that will resolve to a CryptoKey representing the secret key.
function importSecretKey(rawKey) {
return window.crypto.subtle.importKey("raw", rawKey, "AES-GCM", true, [
"encrypt",
"decrypt",
]);
}
importSecretKey(rawKey).then((key) =>
console.log(
`The following usages are reported for this key: ${key.usages.toString()}`,
),
);
Specifications
| Specification |
|---|
| Web Cryptography Level 2 # dom-cryptokey-usages |
Browser compatibility
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