The read-only extractable
property of the CryptoKey
interface indicates whether or not the key may be extracted using SubtleCrypto.exportKey()
or SubtleCrypto.wrapKey()
.
If the key cannot be exported, exportKey()
or wrapKey()
will throw an exception if used to extract it.
A boolean value that is true
if the key can be exported and false
if not.
In this example, the Export button is disabled, and no listener added, if the key cannot be exported.
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}]`;
}
function setExportButton(key) {
const exportButton = document.querySelector(".raw");
exportButton.disabled = !key.extractable;
if (key.extractable) {
exportButton.addEventListener("click", () => {
exportCryptoKey(key);
});
}
}
window.crypto.subtle
.generateKey(
{
name: "AES-GCM",
length: 256,
},
true,
["encrypt", "decrypt"],
)
.then(setExportButton(key));