CryptoKey: extractable 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 insecure contexts (HTTPS), in some or allsupporting browsers.
Note: This feature is available inWeb Workers.
The read-onlyextractable property of theCryptoKey interface indicates whether or not the key may be extracted usingSubtleCrypto.exportKey() orSubtleCrypto.wrapKey().
If the key cannot be exported,exportKey() orwrapKey() will throw an exception if used to extract it.
Value
A boolean value that istrue if the key can be exported andfalse if not.
Examples
In this example, theExport button is disabled, and no listener added, if the key cannot be exported.
js
// Export the given key and write it into the "exported-key" space.async function exportCryptoKey(key) { const exported = await window.crypto.subtle.exportKey("raw", key); const exportedKeyBuffer = new Uint8Array(exported); const exportKeyOutput = document.querySelector(".exported-key"); exportKeyOutput.textContent = `[${exportedKeyBuffer}]`;}// Enable or disable the exportButton if the key is extractable or notfunction setExportButton(key) { const exportButton = document.querySelector(".raw"); // Disable the button if the key is not extractable exportButton.disabled = !key.extractable; if (key.extractable) { // Add an event listener to extract the key exportButton.addEventListener("click", () => { exportCryptoKey(key); }); }}// Generate an encrypt/decrypt secret key,// then enable and set up an event listener on the "Export" button.window.crypto.subtle .generateKey( { name: "AES-GCM", length: 256, }, true, ["encrypt", "decrypt"], ) .then(setExportButton(key));Specifications
| Specification |
|---|
| Web Cryptography Level 2 # dom-cryptokey-extractable |