1# 使用SM4对称密钥（ECB模式）加解密(ArkTS)
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4对应的算法规格请查看[对称密钥加解密算法规格：SM4](crypto-sym-encrypt-decrypt-spec.md#sm4)。
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6**加密**
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8
91. 调用[cryptoFramework.createSymKeyGenerator](../../reference/apis-crypto-architecture-kit/js-apis-cryptoFramework.md#cryptoframeworkcreatesymkeygenerator)、[SymKeyGenerator.generateSymKey](../../reference/apis-crypto-architecture-kit/js-apis-cryptoFramework.md#generatesymkey-1)，生成密钥算法为SM4、密钥长度为128位的对称密钥（SymKey）。
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11   如何生成SM4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：SM4](crypto-sym-key-generation-conversion-spec.md#sm4)和[随机生成对称密钥](crypto-generate-sym-key-randomly.md)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。
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132. 调用[cryptoFramework.createCipher](../../reference/apis-crypto-architecture-kit/js-apis-cryptoFramework.md#cryptoframeworkcreatecipher)，指定字符串参数'SM4_128|ECB|PKCS7'，创建对称密钥类型为SM4_128、分组模式为ECB、填充模式为PKCS7的Cipher实例，用于完成加解密操作。
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153. 调用[Cipher.init](../../reference/apis-crypto-architecture-kit/js-apis-cryptoFramework.md#init-1)，设置模式为加密（CryptoMode.ENCRYPT_MODE），指定加密密钥（SymKey），初始化加密Cipher实例。
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17   ECB模式无加密参数，直接传入null。
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194. 调用[Cipher.update](../../reference/apis-crypto-architecture-kit/js-apis-cryptoFramework.md#update-1)，更新数据（明文）。
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21   - 当数据量较小时，可以在init完成后直接调用doFinal。
22   - 当数据量较大时，可以多次调用update，即分段加解密。
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245. 调用[Cipher.doFinal](../../reference/apis-crypto-architecture-kit/js-apis-cryptoFramework.md#dofinal-1)，获取加密后的数据。
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26   - 由于已使用update传入数据，此处data传入null。
27   - 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。
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29
30**解密**
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331. 调用[Cipher.init](../../reference/apis-crypto-architecture-kit/js-apis-cryptoFramework.md#init-1)，设置模式为解密（CryptoMode.DECRYPT_MODE），指定解密密钥（SymKey）初始化解密Cipher实例。ECB模式无加密参数，直接传入null。
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352. 调用[Cipher.update](../../reference/apis-crypto-architecture-kit/js-apis-cryptoFramework.md#update-1)，更新数据（密文）。
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373. 调用[Cipher.doFinal](../../reference/apis-crypto-architecture-kit/js-apis-cryptoFramework.md#dofinal-1)，获取解密后的数据。
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39
40- 异步方法示例：
41
42  ```ts
43  import { cryptoFramework } from '@kit.CryptoArchitectureKit';
44  import { buffer } from '@kit.ArkTS';
45
46  // 加密消息
47  async function encryptMessagePromise(symKey: cryptoFramework.SymKey, plainText: cryptoFramework.DataBlob) {
48    let cipher = cryptoFramework.createCipher('SM4_128|ECB|PKCS7');
49    await cipher.init(cryptoFramework.CryptoMode.ENCRYPT_MODE, symKey, null);
50    let encryptData = await cipher.doFinal(plainText);
51    return encryptData;
52  }
53  // 解密消息
54  async function decryptMessagePromise(symKey: cryptoFramework.SymKey, cipherText: cryptoFramework.DataBlob) {
55    let decoder = cryptoFramework.createCipher('SM4_128|ECB|PKCS7');
56    await decoder.init(cryptoFramework.CryptoMode.DECRYPT_MODE, symKey, null);
57    let decryptData = await decoder.doFinal(cipherText);
58    return decryptData;
59  }
60  async function genSymKeyByData(symKeyData: Uint8Array) {
61    let symKeyBlob: cryptoFramework.DataBlob = { data: symKeyData };
62    let symGenerator = cryptoFramework.createSymKeyGenerator('SM4_128');
63    let symKey = await symGenerator.convertKey(symKeyBlob);
64    console.info('convertKey success');
65    return symKey;
66  }
67  async function main() {
68    let keyData = new Uint8Array([7, 154, 52, 176, 4, 236, 150, 43, 237, 9, 145, 166, 141, 174, 224, 131]);
69    let symKey = await genSymKeyByData(keyData);
70    let message = "This is a test";
71    let plainText: cryptoFramework.DataBlob = { data: new Uint8Array(buffer.from(message, 'utf-8').buffer) };
72    let encryptText = await encryptMessagePromise(symKey, plainText);
73    let decryptText = await decryptMessagePromise(symKey, encryptText);
74    if (plainText.data.toString() === decryptText.data.toString()) {
75      console.info('decrypt ok');
76      console.info('decrypt plainText: ' + buffer.from(decryptText.data).toString('utf-8'));
77    } else {
78      console.error('decrypt failed');
79    }
80  }
81  ```
82
83- 同步方法示例：
84
85  ```ts
86  import { cryptoFramework } from '@kit.CryptoArchitectureKit';
87  import { buffer } from '@kit.ArkTS';
88
89  // 加密消息
90  function encryptMessage(symKey: cryptoFramework.SymKey, plainText: cryptoFramework.DataBlob) {
91    let cipher = cryptoFramework.createCipher('SM4_128|ECB|PKCS7');
92    cipher.initSync(cryptoFramework.CryptoMode.ENCRYPT_MODE, symKey, null);
93    let encryptData = cipher.doFinalSync(plainText);
94    return encryptData;
95  }
96  // 解密消息
97  function decryptMessage(symKey: cryptoFramework.SymKey, cipherText: cryptoFramework.DataBlob) {
98    let decoder = cryptoFramework.createCipher('SM4_128|ECB|PKCS7');
99    decoder.initSync(cryptoFramework.CryptoMode.DECRYPT_MODE, symKey, null);
100    let decryptData = decoder.doFinalSync(cipherText);
101    return decryptData;
102  }
103  function genSymKeyByData(symKeyData: Uint8Array) {
104    let symKeyBlob: cryptoFramework.DataBlob = { data: symKeyData };
105    let symGenerator = cryptoFramework.createSymKeyGenerator('SM4_128');
106    let symKey = symGenerator.convertKeySync(symKeyBlob);
107    console.info('convertKeySync success');
108    return symKey;
109  }
110  function main() {
111    let keyData = new Uint8Array([7, 154, 52, 176, 4, 236, 150, 43, 237, 9, 145, 166, 141, 174, 224, 131]);
112    let symKey = genSymKeyByData(keyData);
113    let message = "This is a test";
114    let plainText: cryptoFramework.DataBlob = { data: new Uint8Array(buffer.from(message, 'utf-8').buffer) };
115    let encryptText = encryptMessage(symKey, plainText);
116    let decryptText = decryptMessage(symKey, encryptText);
117    if (plainText.data.toString() === decryptText.data.toString()) {
118      console.info('decrypt ok');
119      console.info('decrypt plainText: ' + buffer.from(decryptText.data).toString('utf-8'));
120    } else {
121      console.error('decrypt failed');
122    }
123  }
124  ```