使用AES对称密钥（CCM模式）加解密(ArkTS)

对应的算法规格请查看对称密钥加解密算法规格：AES。

加密

1. 调用cryptoFramework.createSymKeyGenerator、SymKeyGenerator.generateSymKey，生成密钥算法为AES、密钥长度为128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。

2. 调用cryptoFramework.createCipher，指定字符串参数'AES128|CCM'，创建对称密钥类型为AES128、分组模式为CCM的Cipher实例，用于完成加解密操作。

3. 调用Cipher.init，设置模式为加密（CryptoMode.ENCRYPT_MODE），指定加密密钥（SymKey）和CCM模式对应的加密参数（CcmParamsSpec），初始化加密Cipher实例。

4. 调用Cipher.update，更新数据（明文）。

   当前单次update长度没有限制，开发者可以根据数据量判断如何调用update。

   说明

   CCM模式不支持分段加解密。

5. 调用Cipher.doFinal，获取加密后的数据。

   • 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。

6. 读取CcmParamsSpec.authTag作为解密的认证信息。

   在CCM模式下，需要从加密后的数据中取出末尾12字节，作为解密时初始化的认证信息。示例中authTag恰好为12字节。

解密

1. 调用Cipher.init，设置模式为解密（CryptoMode.DECRYPT_MODE），指定解密密钥（SymKey）和CCM模式对应的解密参数（CcmParamsSpec），初始化解密Cipher实例。

2. 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 genCcmParamsSpec() {
    let rand: cryptoFramework.Random = cryptoFramework.createRandom();
    let ivBlob: cryptoFramework.DataBlob = rand.generateRandomSync(7);
    let aadBlob: cryptoFramework.DataBlob = rand.generateRandomSync(8);
    let arr = [0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0]; // 12 bytes
    let dataTag = new Uint8Array(arr);
    let tagBlob: cryptoFramework.DataBlob = {
      data: dataTag
    };
    // CCM的authTag在加密时从doFinal结果中获取，在解密时填入init函数的params参数中
    let ccmParamsSpec: cryptoFramework.CcmParamsSpec = {
      iv: ivBlob,
      aad: aadBlob,
      authTag: tagBlob,
      algName: "CcmParamsSpec"
    };
    return ccmParamsSpec;
  }
  let ccmParams = genCcmParamsSpec();
  
  // 加密消息
  async function encryptMessagePromise(symKey: cryptoFramework.SymKey, plainText: cryptoFramework.DataBlob) {
    let cipher = cryptoFramework.createCipher('AES128|CCM');
    await cipher.init(cryptoFramework.CryptoMode.ENCRYPT_MODE, symKey, ccmParams);
    let encryptUpdate = await cipher.update(plainText);
    // ccm模式加密doFinal时传入空，获得tag数据，并更新至ccmParams对象中。
    ccmParams.authTag = await cipher.doFinal(null);
    return encryptUpdate;
  }
  // 解密消息
  async function decryptMessagePromise(symKey: cryptoFramework.SymKey, cipherText: cryptoFramework.DataBlob) {
    let decoder = cryptoFramework.createCipher('AES128|CCM');
    await decoder.init(cryptoFramework.CryptoMode.DECRYPT_MODE, symKey, ccmParams);
    let decryptUpdate = await decoder.doFinal(cipherText);
    return decryptUpdate;
  }
  async function genSymKeyByData(symKeyData: Uint8Array) {
    let symKeyBlob: cryptoFramework.DataBlob = { data: symKeyData };
    let aesGenerator = cryptoFramework.createSymKeyGenerator('AES128');
    let symKey = await aesGenerator.convertKey(symKeyBlob);
    console.info('convertKey success');
    return symKey;
  }
  async function main() {
    let keyData = new Uint8Array([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');
    }
  }

• 同步方法示例：

  import { cryptoFramework } from '@kit.CryptoArchitectureKit';
  import { buffer } from '@kit.ArkTS';
  
  
  function genCcmParamsSpec() {
    let rand: cryptoFramework.Random = cryptoFramework.createRandom();
    let ivBlob: cryptoFramework.DataBlob = rand.generateRandomSync(7);
    let aadBlob: cryptoFramework.DataBlob = rand.generateRandomSync(8);
    let arr = [0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0]; // 12 bytes
    let dataTag = new Uint8Array(arr);
    let tagBlob: cryptoFramework.DataBlob = {
      data: dataTag
    };
    // CCM的authTag在加密时从doFinal结果中获取，在解密时填入init函数的params参数中
    let ccmParamsSpec: cryptoFramework.CcmParamsSpec = {
      iv: ivBlob,
      aad: aadBlob,
      authTag: tagBlob,
      algName: "CcmParamsSpec"
    };
    return ccmParamsSpec;
  }
  
  let ccmParams = genCcmParamsSpec();
  
  // 加密消息
  function encryptMessage(symKey: cryptoFramework.SymKey, plainText: cryptoFramework.DataBlob) {
    let cipher = cryptoFramework.createCipher('AES128|CCM');
    cipher.initSync(cryptoFramework.CryptoMode.ENCRYPT_MODE, symKey, ccmParams);
    let encryptUpdate = cipher.updateSync(plainText);
    // ccm模式加密doFinal时传入空，获得tag数据，并更新至ccmParams对象中。
    ccmParams.authTag = cipher.doFinalSync(null);
    return encryptUpdate;
  }
  // 解密消息
  function decryptMessage(symKey: cryptoFramework.SymKey, cipherText: cryptoFramework.DataBlob) {
    let decoder = cryptoFramework.createCipher('AES128|CCM');
    decoder.initSync(cryptoFramework.CryptoMode.DECRYPT_MODE, symKey, ccmParams);
    let decryptUpdate = decoder.doFinalSync(cipherText);
    return decryptUpdate;
  }
  function genSymKeyByData(symKeyData: Uint8Array) {
    let symKeyBlob: cryptoFramework.DataBlob = { data: symKeyData };
    let aesGenerator = cryptoFramework.createSymKeyGenerator('AES128');
    let symKey = aesGenerator.convertKeySync(symKeyBlob);
    console.info('convertKeySync success');
    return symKey;
  }
  function main() {
    let keyData = new Uint8Array([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');
    }
  }