在此页

• 句法
• 范例
• 规范
• 浏览器兼容性
• 另请参阅
• 相关话题

安全上下文
此特征只可用于 安全上下文 (HTTPS)，在某些或所有 支持浏览器 .

exportKey() 方法在 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 设为 true .

Keys can be exported in several formats: see Supported formats 在 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.

句法

const result = crypto.subtle.exportKey(format, key);
					

参数

• format is a string value describing the data format in which the key should be exported. It can be one of the following:
  • raw : Raw 格式。
  • pkcs8 : PKCS #8 格式。
  • spki : SubjectPublicKeyInfo 格式。
  • jwk : JSON Web Key 格式。
• key 是 CryptoKey to export.

返回值

• result 是 Promise .
  • 若 format was jwk , then the promise fulfills with a JSON object containing the key.
  • Otherwise the promise fulfills with an ArrayBuffer containing the key.

异常

The promise is rejected when one of the following exceptions is encountered:

InvalidAccessError

Raised when trying to export a non-extractable key.

NotSupported

Raised when trying to export in an unknown format.

TypeError

Raised when trying to use an invalid format.

范例

注意 : You can try the working examples out on GitHub.

Raw export

This 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);
  });
});
					

PKCS #8 export

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://developers.google.com/web/updates/2012/06/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);
  });
});
					

SubjectPublicKeyInfo export

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://developers.google.com/web/updates/2012/06/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);
  });
});
					

JSON Web Key import

This code 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);
  });
});
					

规范

规范	状态	注释
Web Cryptography API The definition of 'SubtleCrypto.exportKey()' in that specification.	推荐	初始定义。

浏览器兼容性

The compatibility table on this page is generated from structured data. If you'd like to contribute to the data, please check out https://github.com/mdn/browser-compat-data and send us a pull request. 更新 GitHub 上的兼容性数据

	桌面						移动
	Chrome	Edge	Firefox	Internet Explorer	Opera	Safari	Android webview	Chrome for Android	Firefox for Android	Opera for Android	Safari on iOS	Samsung Internet
exportKey	Chrome 37	Edge 部分支持 12 部分支持 12 Not supported: RSA-PSS, ECDSA, ECDH. Not supported: AES-CTR.	Firefox 34 34 不支持 32 — 34 Disabled Disabled ). To change preferences in Firefox, visit	IE 部分支持 11 部分支持 11 返回 KeyOperation 而不是 Promise	Opera 24	Safari 7	WebView Android 37	Chrome Android 37	Firefox Android 34 34 不支持 32 — 34 Disabled Disabled ). To change preferences in Firefox, visit	Opera Android 24	Safari iOS 7	Samsung Internet Android 6.0

图例

完整支持

完整支持

部分支持

部分支持

见实现注意事项。

用户必须明确启用此特征。

用户必须明确启用此特征。

另请参阅

• SubtleCrypto.importKey()
• SubtleCrypto.wrapKey()
• PKCS #8 format .
• SubjectPublicKeyInfo format .
• JSON Web Key format .

元数据

• 最后修改： Aug 10, 2020

相关话题

1. Web 加密 API
2. SubtleCrypto
3. 方法

   1. decrypt()
   2. deriveBits()
   3. deriveKey()
   4. digest()
   5. encrypt()
   6. exportKey()
   7. generateKey()
   8. importKey()
   9. sign()
   10. unwrapKey()
   11. verify()
   12. wrapKey()
4. Related pages for Web Crypto API

   1. Crypto
   2. CryptoKey
   3. CryptoKeyPair
   4. RandomSource
   5. Window.crypto