使用AES对称密钥（XTS模式）加解密(ArkTS)

从API版本26.0.0开始，AES对称密钥加解密支持使用XTS分组模式。

密钥生成

调用cryptoFramework.createSymKeyGenerator、SymKeyGenerator.generateSymKey，生成密钥算法为AES、密钥长度为256位的对称密钥（SymKey）。

如何生成AES对称密钥，开发者可参考下文示例，并结合对称密钥生成和转换规格：AES和随机生成对称密钥理解，参考文档与当前示例可能存在入参差异，请在阅读时注意区分。

说明：

AES对称密钥（XTS模式）加解密时，对称密钥长度需要是标准AES密钥的2倍。且只支持创建AES-128、AES-256的cipher实例进行加解密。

示例代码中创建AES256的对称密钥，AES128的cipher实例进行加解密。

加密

调用cryptoFramework.createCipher，指定字符串参数'AES128|XTS'，创建对称密钥类型为AES128、分组模式为XTS的Cipher实例，用于完成加密操作。
调用Cipher.init，设置模式为加密（cryptoFramework.CryptoMode.ENCRYPT_MODE），指定加密密钥（SymKey）和XTS模式对应的加密参数（IvParamsSpec），初始化加密Cipher实例。
当加密内容长度较短时，可以直接调用 Cipher.doFinal 而无需调用update，以获取加密后的数据。

解密

调用cryptoFramework.createCipher，指定字符串参数'AES128|XTS'，创建对称密钥类型为AES128、分组模式为XTS的Cipher实例，用于完成解密操作。
调用Cipher.init，设置模式为解密（cryptoFramework.CryptoMode.DECRYPT_MODE），指定解密密钥（SymKey）和XTS模式对应的解密参数（IvParamsSpec），初始化解密Cipher实例。
当解密内容长度较短时，可以省略调用update，直接调用Cipher.doFinal，获取解密后的数据。

示例

异步方法示例：

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

function generateRandom(len: number) {
  let rand = cryptoFramework.createRandom();
  let generateRandSync = rand.generateRandomSync(len);
  return generateRandSync;
}

function genIvParamsSpec() {
  let ivBlob = generateRandom(16);
  let ivParamsSpec: cryptoFramework.IvParamsSpec = {
    algName: 'IvParamsSpec',
    iv: ivBlob
  };
  return ivParamsSpec;
}

let iv = genIvParamsSpec();

// 加密消息
async function encryptMessagePromise(symKey: cryptoFramework.SymKey, plainText: cryptoFramework.DataBlob) {
  let cipher = cryptoFramework.createCipher('AES128|XTS');
  await cipher.init(cryptoFramework.CryptoMode.ENCRYPT_MODE, symKey, iv);
  let cipherData = await cipher.doFinal(plainText);
  return cipherData;
}

// 解密消息
async function decryptMessagePromise(symKey: cryptoFramework.SymKey, cipherText: cryptoFramework.DataBlob) {
  let decoder = cryptoFramework.createCipher('AES128|XTS');
  await decoder.init(cryptoFramework.CryptoMode.DECRYPT_MODE, symKey, iv);
  let decryptData = await decoder.doFinal(cipherText);
  return decryptData;
}

export async function aesXTS() : Promise<string> {
  try {
    let symGenerator = cryptoFramework.createSymKeyGenerator('AES256')
    let symKey = await symGenerator.generateSymKey()
    let message = 'This is a xts encrypt decrypt test';
    let plainText: cryptoFramework.DataBlob = { data: new Uint8Array(buffer.from(message, 'utf-8').buffer) };
    let encryptText = await encryptMessagePromise(symKey, plainText);
    let decryptText = await decryptMessagePromise(symKey, encryptText);
    if (plainText.data.toString() === decryptText.data.toString()) {
      console.info('decrypt ok');
      console.info('decrypt plainText: ' + buffer.from(decryptText.data).toString('utf-8'));
    } else {
      console.error('decrypt failed');
    }
    return 'success';
  } catch (error) {
    console.error('xts decrypt failed. error: ' + error);
    return 'fail';
  }
}

aes_xts_encryption_decryption_asynchronous.ets

同步方法示例：

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

function generateRandom(len: number) {
  let rand = cryptoFramework.createRandom();
  let generateRandSync = rand.generateRandomSync(len);
  return generateRandSync;
}

function genIvParamsSpec() {
  let ivBlob = generateRandom(16);
  let ivParamsSpec: cryptoFramework.IvParamsSpec = {
    algName: 'IvParamsSpec',
    iv: ivBlob
  };
  return ivParamsSpec;
}

let iv = genIvParamsSpec();

// 加密消息
function encryptMessage(symKey: cryptoFramework.SymKey, plainText: cryptoFramework.DataBlob) {
  let cipher = cryptoFramework.createCipher('AES128|XTS');
  cipher.initSync(cryptoFramework.CryptoMode.ENCRYPT_MODE, symKey, iv);
  let cipherData = cipher.doFinalSync(plainText);
  return cipherData;
}

// 解密消息
function decryptMessage(symKey: cryptoFramework.SymKey, cipherText: cryptoFramework.DataBlob) {
  let decoder = cryptoFramework.createCipher('AES128|XTS');
  decoder.initSync(cryptoFramework.CryptoMode.DECRYPT_MODE, symKey, iv);
  let decryptData = decoder.doFinalSync(cipherText);
  return decryptData;
}

export function aesXTS() : string {
  try {
    let symGenerator = cryptoFramework.createSymKeyGenerator('AES256')
    let symKey = symGenerator.generateSymKeySync()
    let message = 'This is a xts encrypt decrypt test';
    let plainText: cryptoFramework.DataBlob = { data: new Uint8Array(buffer.from(message, 'utf-8').buffer) };
    let encryptText = encryptMessage(symKey, plainText);
    let decryptText = decryptMessage(symKey, encryptText);
    if (plainText.data.toString() === decryptText.data.toString()) {
      console.info('decrypt ok.');
      console.info('decrypt plainText: ' + buffer.from(decryptText.data).toString('utf-8'));
    } else {
      console.error('decrypt failed.');
    }
    return 'success';
  } catch (error) {
    console.error('xts decrypt failed. error: ' + error);
    return 'fail';
  }
}

aes_xts_encryption_decryption_synchronous.ets