使用ChaCha20对称密钥加解密(ArkTS)

从API22开始，算法库支持该算法。

对应的算法规格请查看对称密钥加解密算法规格：ChaCha20。

开发步骤

创建对象

调用cryptoFramework.createSymKeyGenerator、SymKeyGenerator.generateSymKey，生成密钥算法为ChaCha20的对称密钥（SymKey）。

如何生成ChaCha20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：ChaCha20和随机生成对称密钥理解。参考文档与示例可能存在入参差异，请注意区分。

加密

1. 调用cryptoFramework.createCipher，指定字符串参数'ChaCha20'，创建对称密钥的Cipher实例，用于完成加密操作。

2. 调用Cipher.init，设置模式为加密（CryptoMode.ENCRYPT_MODE），指定加密密钥（SymKey）和对应的加密参数（IvParamsSpec），初始化加密Cipher实例。

3. 调用Cipher.update，更新数据（明文）。

4. 调用Cipher.doFinal，获取加密后的数据。

   说明

   由于已使用update传入数据，此处data传入null。

   doFinal输出结果可能为null，在访问具体数据前，需要先判断结果是否为null，避免产生异常。

解密

1. 调用cryptoFramework.createCipher，指定字符串参数'ChaCha20'，创建对称密钥的Cipher实例，用于完成解密操作。

2. 调用Cipher.init，设置模式为解密（CryptoMode.DECRYPT_MODE），指定解密密钥（SymKey）和对应的解密参数（IvParamsSpec），初始化解密Cipher实例。

3. 调用Cipher.update，更新数据（密文）。

4. 调用Cipher.doFinal，获取解密后的数据。

• 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 ivSpec = genIvParamsSpec();
  
  // 加密消息。
  async function encryptMessagePromise(symKey: cryptoFramework.SymKey, plainText: cryptoFramework.DataBlob) {
    let cipher = cryptoFramework.createCipher('ChaCha20');
    await cipher.init(cryptoFramework.CryptoMode.ENCRYPT_MODE, symKey, ivSpec);
    let encryptUpdata = await cipher.doFinal(plainText);
    return encryptUpdata;
  }
  // 解密消息。
  async function decryptMessagePromise(symKey: cryptoFramework.SymKey, cipherText: cryptoFramework.DataBlob) {
    let decoder = cryptoFramework.createCipher('ChaCha20');
    await decoder.init(cryptoFramework.CryptoMode.DECRYPT_MODE, symKey, ivSpec);
    let decryptUpdata = await decoder.doFinal(cipherText);
    return decryptUpdata;
  }
  async function genSymKeyByData(symKeyData: Uint8Array) {
    let symKeyBlob: cryptoFramework.DataBlob = { data: symKeyData };
    let chacha20Generator = cryptoFramework.createSymKeyGenerator('ChaCha20');
    let symKey = await chacha20Generator.convertKey(symKeyBlob);
    console.info('convertKey success');
    return symKey;
  }
  async function main() {
    try {
      let keyData = new Uint8Array([83, 217, 231, 76, 28, 113, 23, 219, 250, 71, 209, 210, 205, 97, 32, 159, 83,
        217, 231, 76, 28, 113, 23, 219, 250, 71, 209, 210, 205, 97, 32, 159]);
      let symKey = await genSymKeyByData(keyData);
      let message = "This is a 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');
      }
    } catch (error) {
      console.error(`decrypt failed, error info is ${error}, error code: ${error.code}`);
    }
  }
  

• 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 ivSpec = genIvParamsSpec();
  
  // 加密消息。
  function encryptMessage(symKey: cryptoFramework.SymKey, plainText: cryptoFramework.DataBlob) {
    let cipher = cryptoFramework.createCipher('ChaCha20');
    cipher.initSync(cryptoFramework.CryptoMode.ENCRYPT_MODE, symKey, ivSpec);
    let encryptUpdata = cipher.doFinalSync(plainText);
    return encryptUpdata;
  }
  // 解密消息。
  function decryptMessage(symKey: cryptoFramework.SymKey, cipherText: cryptoFramework.DataBlob) {
    let decoder = cryptoFramework.createCipher('ChaCha20');
    decoder.initSync(cryptoFramework.CryptoMode.DECRYPT_MODE, symKey, ivSpec);
    let decryptdata = decoder.updateSync(cipherText);
    return decryptdata;
  }
  function genSymKeyByData(symKeyData: Uint8Array) {
    let symKeyBlob: cryptoFramework.DataBlob = { data: symKeyData };
    let chacha20Generator = cryptoFramework.createSymKeyGenerator('ChaCha20');
    let symKey = chacha20Generator.convertKeySync(symKeyBlob);
    console.info('convertKeySync success');
    return symKey;
  }
  async function main() {
    try {
      let keyData = new Uint8Array([83, 217, 231, 76, 28, 113, 23, 219, 250, 71, 209, 210, 205, 97, 32, 159, 83,
        217, 231, 76, 28, 113, 23, 219, 250, 71, 209, 210, 205, 97, 32, 159]);
      let symKey = genSymKeyByData(keyData);
      let message = "This is a 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.');
      }
    } catch (error) {
      console.error(`decrypt failed, error info is ${error}, error code: ${error.code}`);
    }
  }