使用AES对称密钥（GCM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](https://developer.huawei.com/consumer/cn/doc/harmonyos-guides/crypto-sym-encrypt-decrypt-spec#aes)。

**加密**

1.  调用[cryptoFramework.createSymKeyGenerator](https://developer.huawei.com/consumer/cn/doc/harmonyos-references/js-apis-cryptoframework#cryptoframeworkcreatesymkeygenerator)，生成密钥算法为AES、密钥长度为128位的对称密钥（SymKey）。然后调用[SymKeyGenerator.generateSymKey](https://developer.huawei.com/consumer/cn/doc/harmonyos-references/js-apis-cryptoframework#generatesymkey-1)生成对称密钥。
    
    如何生成AES对称密钥，开发者可以参考以下示例，并结合[对称密钥生成和转换规格：AES](https://developer.huawei.com/consumer/cn/doc/harmonyos-guides/crypto-sym-key-generation-conversion-spec#aes)和[随机生成对称密钥](https://developer.huawei.com/consumer/cn/doc/harmonyos-guides/crypto-generate-sym-key-randomly)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](https://developer.huawei.com/consumer/cn/doc/harmonyos-references/js-apis-cryptoframework#cryptoframeworkcreatecipher)，指定字符串参数'AES128|GCM'，创建对称密钥类型为AES128、分组模式为GCM的Cipher实例，用于完成加密操作。
    
3.  调用[Cipher.init](https://developer.huawei.com/consumer/cn/doc/harmonyos-references/js-apis-cryptoframework#init-1)，设置模式为加密（cryptoFramework.CryptoMode.ENCRYPT\_MODE），指定加密密钥（SymKey）和GCM模式对应的加密参数（GcmParamsSpec），以初始化加密Cipher实例。
    
4.  调用[Cipher.update](https://developer.huawei.com/consumer/cn/doc/harmonyos-references/js-apis-cryptoframework#update-1)，更新数据（明文）。
    
    当前单次update无长度限制，开发者可根据数据量调用update。
    
    *   当数据量较小时，可以在init完成后直接调用doFinal。
    *   当数据量较大时，可以多次调用update，即[分段加解密](https://developer.huawei.com/consumer/cn/doc/harmonyos-guides/crypto-aes-sym-encrypt-decrypt-gcm-by-segment)。
5.  调用[Cipher.doFinal](https://developer.huawei.com/consumer/cn/doc/harmonyos-references/js-apis-cryptoframework#dofinal-1)，获取加密后的数据。注意，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。
    
    *   已使用update传入数据，data传入null。
    *   doFinal输出可能为null，访问数据前先判断结果。
6.  读取[GcmParamsSpec](https://developer.huawei.com/consumer/cn/doc/harmonyos-references/js-apis-cryptoframework#gcmparamsspec).authTag作为解密的认证信息。
    
    在GCM模式下，算法库目前仅支持16字节的authTag，用于解密时的初始化认证。示例中的authTag恰好为16字节。
    

**解密**

1.  调用[cryptoFramework.createCipher](https://developer.huawei.com/consumer/cn/doc/harmonyos-references/js-apis-cryptoframework#cryptoframeworkcreatecipher)，指定字符串参数'AES128|GCM'，创建对称密钥类型为AES128、分组模式为GCM的Cipher实例，用于完成解密操作。
    
2.  调用[Cipher.init](https://developer.huawei.com/consumer/cn/doc/harmonyos-references/js-apis-cryptoframework#init-1)，设置模式为解密（cryptoFramework.CryptoMode.DECRYPT\_MODE），指定解密密钥（SymKey）和GCM模式对应的解密参数（GcmParamsSpec），初始化解密Cipher实例。
    
3.  调用[Cipher.update](https://developer.huawei.com/consumer/cn/doc/harmonyos-references/js-apis-cryptoframework#update-1)，更新数据（密文）。
    
4.  调用[Cipher.doFinal](https://developer.huawei.com/consumer/cn/doc/harmonyos-references/js-apis-cryptoframework#dofinal-1)，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 genGcmParamsSpec() {
      let ivBlob = generateRandom(12);
      let arr = \[1, 2, 3, 4, 5, 6, 7, 8\]; // 8 bytes
      let dataAad = new Uint8Array(arr);
      let aadBlob: cryptoFramework.DataBlob = { data: dataAad };
      arr = \[0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0\]; // 16 bytes
      let dataTag = new Uint8Array(arr);
      let tagBlob: cryptoFramework.DataBlob = {
        data: dataTag
      };
      // GCM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 gcmParamsSpec: cryptoFramework.GcmParamsSpec = {
        iv: ivBlob,
        aad: aadBlob,
        authTag: tagBlob,
        algName: 'GcmParamsSpec'
      };
      return gcmParamsSpec;
    }
    
    let gcmParams = genGcmParamsSpec();
    
    // 加密消息
    async function encryptMessagePromise(symKey: cryptoFramework.SymKey, plainText: cryptoFramework.DataBlob) {
      let cipher = cryptoFramework.createCipher('AES128|GCM');
      await cipher.init(cryptoFramework.CryptoMode.ENCRYPT\_MODE, symKey, gcmParams);
      let encryptUpdate = await cipher.update(plainText);
      // gcm模式加密doFinal时传入空，获得tag数据，并更新至gcmParams对象中。
      gcmParams.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|GCM');
      await decoder.init(cryptoFramework.CryptoMode.DECRYPT\_MODE, symKey, gcmParams);
      let decryptUpdate = await decoder.update(cipherText);
      // gcm模式解密doFinal时传入空，验证init时传入的tag数据，如果验证失败会抛出异常。
      let decryptData = await decoder.doFinal(null);
      if (decryptData == null) {
        console.info('GCM decrypt result: success, decryptData is null.');
      }
      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 result: 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 generateRandom(len: number) {
      let rand = cryptoFramework.createRandom();
      let generateRandSync = rand.generateRandomSync(len);
      return generateRandSync;
    }
    
    function genGcmParamsSpec() {
      let ivBlob = generateRandom(12);
      let arr = \[1, 2, 3, 4, 5, 6, 7, 8\]; // 8 bytes
      let dataAad = new Uint8Array(arr);
      let aadBlob: cryptoFramework.DataBlob = { data: dataAad };
      arr = \[0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0\]; // 16 bytes
      let dataTag = new Uint8Array(arr);
      let tagBlob: cryptoFramework.DataBlob = {
        data: dataTag
      };
      // GCM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 gcmParamsSpec: cryptoFramework.GcmParamsSpec = {
        iv: ivBlob,
        aad: aadBlob,
        authTag: tagBlob,
        algName: 'GcmParamsSpec'
      };
      return gcmParamsSpec;
    }
    
    let gcmParams = genGcmParamsSpec();
    
    // 加密消息
    function encryptMessage(symKey: cryptoFramework.SymKey, plainText: cryptoFramework.DataBlob) {
      let cipher = cryptoFramework.createCipher('AES128|GCM');
      cipher.initSync(cryptoFramework.CryptoMode.ENCRYPT\_MODE, symKey, gcmParams);
      let encryptUpdate = cipher.updateSync(plainText);
      // gcm模式加密doFinal时传入空，获得tag数据，并更新至gcmParams对象中。
      gcmParams.authTag = cipher.doFinalSync(null);
      return encryptUpdate;
    }
    
    // 解密消息
    function decryptMessage(symKey: cryptoFramework.SymKey, cipherText: cryptoFramework.DataBlob) {
      let decoder = cryptoFramework.createCipher('AES128|GCM');
      decoder.initSync(cryptoFramework.CryptoMode.DECRYPT\_MODE, symKey, gcmParams);
      let decryptUpdate = decoder.updateSync(cipherText);
      // gcm模式解密doFinal时传入空，验证init时传入的tag数据，如果验证失败会抛出异常。
      let decryptData = decoder.doFinalSync(null);
      if (decryptData == null) {
        console.info('GCM decrypt result: success, decryptData is null.');
      }
      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 result: 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.');
      }
    }