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
.
deriveBits()
方法在
SubtleCrypto
interface can be used to derive an array of bits from a base key.
It takes as its arguments the base key, the derivation algorithm to use, and the length of the bit string to derive. It returns a
Promise
which will be fulfilled with an
ArrayBuffer
containing the derived bits.
This method is very similar to
SubtleCrypto.deriveKey()
，除了
deriveKey()
返回
CryptoKey
object rather than an
ArrayBuffer
. Essentially
deriveKey()
is composed of
deriveBits()
followed by
importKey()
.
This function supports the same derivation algorithms as
deriveKey()
: ECDH, HKDF, and PBKDF2. See
Supported algorithms
for some more detail on these algorithms.
const result = crypto.subtle.deriveBits(
algorithm,
baseKey,
length
);
algorithm
is an object defining the
derivation algorithm
to use.
EcdhKeyDeriveParams
对象。
HkdfParams
对象。
Pbkdf2Params
对象。
baseKey
是
CryptoKey
representing the input to the derivation algorithm. If
algorithm
is ECDH, this will be the ECDH private key. Otherwise it will be the initial key material for the derivation function: for example, for PBKDF2 it might be a password, imported as a
CryptoKey
使用
SubtleCrypto.importKey()
.
length
is a number representing the number of bits to derive.
result
是
Promise
that fulfills with an
ArrayBuffer
containing the derived bits.
The promise is rejected when one of the following exceptions are encountered:
InvalidAccessError
CryptoKey.usages
value of that key doesn't contain
deriveKey
.
NotSupported
Raised when trying to use an algorithm that is either unknown or isn't suitable for derivation, or if the algorithm requested for the derived key doesn't define a key length.
见
Supported algorithms section of the
deriveKey()
文档编制
.
注意 : You can try the working examples on GitHub.
In this example Alice and Bob each generate an ECDH key pair.
We then use Alice's private key and Bob's public key to derive a shared secret. See the complete code on GitHub.
async function deriveSharedSecret(privateKey, publicKey) {
const sharedSecret = await window.crypto.subtle.deriveBits(
{
name: "ECDH",
namedCurve: "P-384",
public: publicKey
},
privateKey,
128
);
const buffer = new Uint8Array(sharedSecret, 0, 5);
const sharedSecretValue = document.querySelector(".ecdh .derived-bits-value");
sharedSecretValue.classList.add("fade-in");
sharedSecretValue.addEventListener("animationend", () => {
sharedSecretValue.classList.remove("fade-in");
});
sharedSecretValue.textContent = `${buffer}...[${sharedSecret.byteLength} bytes total]`;
}
// Generate 2 ECDH key pairs: one for Alice and one for Bob
// In more normal usage, they would generate their key pairs
// separately and exchange public keys securely
const generateAlicesKeyPair = window.crypto.subtle.generateKey(
{
name: "ECDH",
namedCurve: "P-384"
},
false,
["deriveBits"]
);
const generateBobsKeyPair = window.crypto.subtle.generateKey(
{
name: "ECDH",
namedCurve: "P-384"
},
false,
["deriveBits"]
);
Promise.all([generateAlicesKeyPair, generateBobsKeyPair]).then(values => {
const alicesKeyPair = values[0];
const bobsKeyPair = values[1];
const deriveBitsButton = document.querySelector(".ecdh .derive-bits-button");
deriveBitsButton.addEventListener("click", () => {
// Alice then generates a secret using her private key and Bob's public key.
// Bob could generate the same secret using his private key and Alice's public key.
deriveSharedSecret(alicesKeyPair.privateKey, bobsKeyPair.publicKey);
});
});
In this example we ask the user for a password, then use it to derive some bits using PBKDF2. See the complete code on GitHub.
let salt;
/*
Get some key material to use as input to the deriveBits method.
The key material is a password supplied by the user.
*/
function getKeyMaterial() {
const password = window.prompt("Enter your password");
const enc = new TextEncoder();
return window.crypto.subtle.importKey(
"raw",
enc.encode(password),
{name: "PBKDF2"},
false,
["deriveBits", "deriveKey"]
);
}
/*
Derive some bits from a password supplied by the user.
*/
async function getDerivedBits() {
const keyMaterial = await getKeyMaterial();
salt = window.crypto.getRandomValues(new Uint8Array(16));
const derivedBits = await window.crypto.subtle.deriveBits(
{
"name": "PBKDF2",
salt: salt,
"iterations": 100000,
"hash": "SHA-256"
},
keyMaterial,
256
);
const buffer = new Uint8Array(derivedBits, 0, 5);
const derivedBitsValue = document.querySelector(".pbkdf2 .derived-bits-value");
derivedBitsValue.classList.add("fade-in");
derivedBitsValue.addEventListener("animationend", () => {
derivedBitsValue.classList.remove("fade-in");
});
derivedBitsValue.textContent = `${buffer}...[${derivedBits.byteLength} bytes total]`;
}
const deriveBitsButton = document.querySelector(".pbkdf2 .derive-bits-button");
deriveBitsButton.addEventListener("click", () => {
getDerivedBits();
});
| 规范 | 状态 | 注释 |
|---|---|---|
|
Web Cryptography API
The definition of 'SubtleCrypto.deriveBits()' in that specification. |
推荐 | 初始定义。 |
| 桌面 | 移动 | |||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|
deriveBits
|
Chrome 37 |
Edge
部分支持
12
|
Firefox
34
|
IE No | Opera 24 | Safari 7 | WebView Android 37 | Chrome Android 37 |
Firefox Android
34
|
Opera Android 24 | Safari iOS 7 | Samsung Internet Android 6.0 |
完整支持
部分支持
不支持
见实现注意事项。
用户必须明确启用此特征。
SubtleCrypto