Baseline Widely available *
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 exportKey() method of the SubtleCrypto interface exports a key: that is, it takes as input a CryptoKey object and gives you the key in an external, portable format.
To export a key, the key must have CryptoKey.extractable set to true.
Keys can be exported in several formats: see Supported formats in the SubtleCrypto.importKey() page for details.
Keys are not exported in an encrypted format: to encrypt keys when exporting them use the SubtleCrypto.wrapKey() API instead.
format
A string value describing the data format in which the key should be exported. It can be one of the following:
raw: Raw format.pkcs8: PKCS #8 format.spki: SubjectPublicKeyInfo format.jwk: JSON Web Key format.key
The CryptoKey to export.
A Promise.
format was jwk, then the promise fulfills with a JSON object containing the key.ArrayBuffer containing the key.The promise is rejected when one of the following exceptions is encountered:
InvalidAccessError DOMException
Raised when trying to export a non-extractable key.
NotSupported DOMException
Raised when trying to export in an unknown format.
TypeError
Raised when trying to use an invalid format.
Note: You can try the working examples out on GitHub.
Raw exportThis example exports an AES key as an ArrayBuffer containing the bytes for the key. See the complete code on GitHub.
/*
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 = `[${exportedKeyBuffer}]`;
}
/*
Generate an encrypt/decrypt secret key,
then set up an event listener on the "Export" button.
*/
window.crypto.subtle
.generateKey(
{
name: "AES-GCM",
length: 256,
},
true,
["encrypt", "decrypt"],
)
.then((key) => {
const exportButton = document.querySelector(".raw");
exportButton.addEventListener("click", () => {
exportCryptoKey(key);
});
});
This example exports an RSA private signing key as a PKCS #8 object. The exported key is then PEM-encoded. See the complete code on GitHub.
/*
Convert an ArrayBuffer into a string
from https://developer.chrome.com/blog/how-to-convert-arraybuffer-to-and-from-string/
*/
function ab2str(buf) {
return String.fromCharCode.apply(null, new Uint8Array(buf));
}
/*
Export the given key and write it into the "exported-key" space.
*/
async function exportCryptoKey(key) {
const exported = await window.crypto.subtle.exportKey("pkcs8", key);
const exportedAsString = ab2str(exported);
const exportedAsBase64 = window.btoa(exportedAsString);
const pemExported = `-----BEGIN PRIVATE KEY-----\n${exportedAsBase64}\n-----END PRIVATE KEY-----`;
const exportKeyOutput = document.querySelector(".exported-key");
exportKeyOutput.textContent = pemExported;
}
/*
Generate a sign/verify key pair,
then set up an event listener on the "Export" button.
*/
window.crypto.subtle
.generateKey(
{
name: "RSA-PSS",
// Consider using a 4096-bit key for systems that require long-term security
modulusLength: 2048,
publicExponent: new Uint8Array([1, 0, 1]),
hash: "SHA-256",
},
true,
["sign", "verify"],
)
.then((keyPair) => {
const exportButton = document.querySelector(".pkcs8");
exportButton.addEventListener("click", () => {
exportCryptoKey(keyPair.privateKey);
});
});
This example exports an RSA public encryption key as a PEM-encoded SubjectPublicKeyInfo object. See the complete code on GitHub.
/*
Convert an ArrayBuffer into a string
from https://developer.chrome.com/blog/how-to-convert-arraybuffer-to-and-from-string/
*/
function ab2str(buf) {
return String.fromCharCode.apply(null, new Uint8Array(buf));
}
/*
Export the given key and write it into the "exported-key" space.
*/
async function exportCryptoKey(key) {
const exported = await window.crypto.subtle.exportKey("spki", key);
const exportedAsString = ab2str(exported);
const exportedAsBase64 = window.btoa(exportedAsString);
const pemExported = `-----BEGIN PUBLIC KEY-----\n${exportedAsBase64}\n-----END PUBLIC KEY-----`;
const exportKeyOutput = document.querySelector(".exported-key");
exportKeyOutput.textContent = pemExported;
}
/*
Generate an encrypt/decrypt key pair,
then set up an event listener on the "Export" button.
*/
window.crypto.subtle
.generateKey(
{
name: "RSA-OAEP",
// Consider using a 4096-bit key for systems that require long-term security
modulusLength: 2048,
publicExponent: new Uint8Array([1, 0, 1]),
hash: "SHA-256",
},
true,
["encrypt", "decrypt"],
)
.then((keyPair) => {
const exportButton = document.querySelector(".spki");
exportButton.addEventListener("click", () => {
exportCryptoKey(keyPair.publicKey);
});
});
This example exports an ECDSA private signing key as a JSON Web Key object. See the complete code on GitHub.
/*
Export the given key and write it into the "exported-key" space.
*/
async function exportCryptoKey(key) {
const exported = await window.crypto.subtle.exportKey("jwk", key);
const exportKeyOutput = document.querySelector(".exported-key");
exportKeyOutput.textContent = JSON.stringify(exported, null, " ");
}
/*
Generate a sign/verify key pair,
then set up an event listener on the "Export" button.
*/
window.crypto.subtle
.generateKey(
{
name: "ECDSA",
namedCurve: "P-384",
},
true,
["sign", "verify"],
)
.then((keyPair) => {
const exportButton = document.querySelector(".jwk");
exportButton.addEventListener("click", () => {
exportCryptoKey(keyPair.privateKey);
});
});
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