使用HKDF进行密钥派生(ArkTS)

开发步骤

构造HKDFSpec对象，作为密钥派生参数进行密钥派生。

HKDFSpec是KdfSpec的子类，需要指定：
- algName：指定算法'HKDF'。
- key：原始密钥材料。如果使用string类型，需要直接传入用于密钥派生的数据，而不是HexString、base64等字符串类型。同时需要确保该字符串为utf-8编码，否则派生结果会有差异。
- salt：盐值。
- info：可选的上下文与应用相关信息，可为空，用于拓展短密钥。
- keySize：目标密钥的字节长度，需要为正整数。
调用cryptoFramework.createKdf，指定字符串参数'HKDF|SHA256|EXTRACT_AND_EXPAND'，创建密钥派生算法为HKDF、HMAC函数摘要算法为SHA256、模式为提取和拓展的密钥派生函数对象（Kdf）。
输入HKDFSpec对象，调用Kdf.generateSecret进行密钥派生。

Kdf.generateSecret的多种调用形式如表所示。

接口名	返回方式
generateSecret(params: KdfSpec, callback: AsyncCallback<DataBlob>): void	callback异步生成。
generateSecret(params: KdfSpec): Promise<DataBlob>	Promise异步生成。
generateSecretSync(params: KdfSpec): DataBlob	同步生成。

通过await返回结果：

import { cryptoFramework } from '@kit.CryptoArchitectureKit';
import { buffer } from '@kit.ArkTS';

async function kdfAwait() {
  let keyData = new Uint8Array(buffer.from("012345678901234567890123456789", "utf-8").buffer);
  let saltData = new Uint8Array(buffer.from("0123456789", "utf-8").buffer);
  let infoData = new Uint8Array(buffer.from("infostring", "utf-8").buffer);
  let spec: cryptoFramework.HKDFSpec = {
    algName: 'HKDF',
    key: keyData,
    salt: saltData,
    info: infoData,
    keySize: 32
  };
  let kdf = cryptoFramework.createKdf('HKDF|SHA256|EXTRACT_AND_EXPAND');
  let secret = await kdf.generateSecret(spec);
  console.info("key derivation output is " + secret.data);
}

通过Promise返回结果：

import { cryptoFramework } from '@kit.CryptoArchitectureKit';
import { BusinessError } from '@kit.BasicServicesKit';
import { buffer } from '@kit.ArkTS';

function kdfPromise() {
  let keyData = new Uint8Array(buffer.from("012345678901234567890123456789", "utf-8").buffer);
  let saltData = new Uint8Array(buffer.from("0123456789", "utf-8").buffer);
  let infoData = new Uint8Array(buffer.from("infostring", "utf-8").buffer);
  let spec: cryptoFramework.HKDFSpec = {
    algName: 'HKDF',
    key: keyData,
    salt: saltData,
    info: infoData,
    keySize: 32
  };
  let kdf = cryptoFramework.createKdf('HKDF|SHA256|EXTRACT_AND_EXPAND');
  let kdfPromise = kdf.generateSecret(spec);
  kdfPromise.then((secret) => {
    console.info("key derivation output is " + secret.data);
  }).catch((error: BusinessError) => {
    console.error("key derivation error.");
  });
}

通过同步方式返回结果：

import { cryptoFramework } from '@kit.CryptoArchitectureKit';
import { BusinessError } from '@kit.BasicServicesKit';
import { buffer } from '@kit.ArkTS';

function kdfSync() {
  let keyData = new Uint8Array(buffer.from("012345678901234567890123456789", "utf-8").buffer);
  let saltData = new Uint8Array(buffer.from("0123456789", "utf-8").buffer);
  let infoData = new Uint8Array(buffer.from("infostring", "utf-8").buffer);
  let spec: cryptoFramework.HKDFSpec = {
    algName: 'HKDF',
    key: keyData,
    salt: saltData,
    info: infoData,
    keySize: 32
  };
  let kdf = cryptoFramework.createKdf('HKDF|SHA256|EXTRACT_AND_EXPAND');
  let secret = kdf.generateSecretSync(spec);
  console.info("[Sync]key derivation output is " + secret.data);
}