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1# 使用AES对称密钥（CCM模式）加解密(ArkTS)
2
3<!--Kit: Crypto Architecture Kit-->
4<!--Subsystem: Security-->
5<!--Owner: @zxz--3-->
6<!--Designer: @lanming-->
7<!--Tester: @PAFT-->
8<!--Adviser: @zengyawen-->
9
10查看[对称密钥加解密算法规格：AES](crypto-sym-encrypt-decrypt-spec.md#aes)。
11
12**加密**
13
141. 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AES、密钥长度为128位的对称密钥（SymKey）。
15
16   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](crypto-sym-key-generation-conversion-spec.md#aes)和[随机生成对称密钥](crypto-generate-sym-key-randomly.md)进行理解，参考文档与当前示例可能存在入参差异，请注意区分。
17
182. 调用[cryptoFramework.createCipher](../../reference/apis-crypto-architecture-kit/js-apis-cryptoFramework.md#cryptoframeworkcreatecipher)，指定字符串参数'AES128|CCM'，创建对称密钥为AES128、分组模式为CCM的Cipher实例，用于执行加密操作。
19
203. 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），指定密钥（SymKey）和CCM模式对应的加密参数（CcmParamsSpec），初始化加密Cipher实例。
21
224. 调用[Cipher.update](../../reference/apis-crypto-architecture-kit/js-apis-cryptoFramework.md#update-1)，更新数据（明文）。
23
24   当前单次update没有长度限制，开发者可以根据数据量决定如何调用update。
25
26   > **说明：**
27   > CCM模式不支持分段加解密。
28
295. 调用[Cipher.doFinal](../../reference/apis-crypto-architecture-kit/js-apis-cryptoFramework.md#dofinal-1)获取加密后的数据。
30   - 由于已通过update传入数据，此处传入null。
31   - doFinal输出结果可能为null，访问具体数据前，需先判断结果是否为null，以避免异常。
32
336. 读取[CcmParamsSpec.authTag](../../reference/apis-crypto-architecture-kit/js-apis-cryptoFramework.md#ccmparamsspec)作为解密的认证信息。
34
35    在CCM模式下，算法库目前仅支持12字节的authTag，用于解密时的初始化认证信息。示例中的authTag为12字节。
36
37**解密**
38
391. 调用[cryptoFramework.createCipher](../../reference/apis-crypto-architecture-kit/js-apis-cryptoFramework.md#cryptoframeworkcreatecipher)，指定字符串参数'AES128|CCM'，创建对称密钥为AES128、分组模式为CCM的Cipher实例，用于完成解密操作。
40
412. 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），指定密钥（SymKey）和CCM模式对应的解密参数（CcmParamsSpec），初始化解密Cipher实例。
42
433. 调用[Cipher.doFinal](../../reference/apis-crypto-architecture-kit/js-apis-cryptoFramework.md#dofinal-1)，获取解密后的数据。
44
45- 异步方法示例：
46
47  ```ts
48  import { cryptoFramework } from '@kit.CryptoArchitectureKit';
49  import { buffer } from '@kit.ArkTS';
50
51  function genCcmParamsSpec() {
52    let rand: cryptoFramework.Random = cryptoFramework.createRandom();
53    let ivBlob: cryptoFramework.DataBlob = rand.generateRandomSync(7);
54    let aadBlob: cryptoFramework.DataBlob = rand.generateRandomSync(8);
55    let arr = [0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0]; // 12 bytes
56    let dataTag = new Uint8Array(arr);
57    let tagBlob: cryptoFramework.DataBlob = {
58      data: dataTag
59    };
60    // 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。
61    let ccmParamsSpec: cryptoFramework.CcmParamsSpec = {
62      iv: ivBlob,
63      aad: aadBlob,
64      authTag: tagBlob,
65      algName: "CcmParamsSpec"
66    };
67    return ccmParamsSpec;
68  }
69  let ccmParams = genCcmParamsSpec();
70
71  // 加密消息。
72  async function encryptMessagePromise(symKey: cryptoFramework.SymKey, plainText: cryptoFramework.DataBlob) {
73    let cipher = cryptoFramework.createCipher('AES128|CCM');
74    await cipher.init(cryptoFramework.CryptoMode.ENCRYPT_MODE, symKey, ccmParams);
75    let encryptUpdate = await cipher.update(plainText);
76    // ccm模式加密doFinal时传入空，获得tag数据，并更新至ccmParams对象中。
77    ccmParams.authTag = await cipher.doFinal(null);
78    return encryptUpdate;
79  }
80  // 解密消息。
81  async function decryptMessagePromise(symKey: cryptoFramework.SymKey, cipherText: cryptoFramework.DataBlob) {
82    let decoder = cryptoFramework.createCipher('AES128|CCM');
83    await decoder.init(cryptoFramework.CryptoMode.DECRYPT_MODE, symKey, ccmParams);
84    let decryptUpdate = await decoder.doFinal(cipherText);
85    return decryptUpdate;
86  }
87  async function genSymKeyByData(symKeyData: Uint8Array) {
88    let symKeyBlob: cryptoFramework.DataBlob = { data: symKeyData };
89    let aesGenerator = cryptoFramework.createSymKeyGenerator('AES128');
90    let symKey = await aesGenerator.convertKey(symKeyBlob);
91    console.info('convertKey success');
92    return symKey;
93  }
94  async function main() {
95    let keyData = new Uint8Array([83, 217, 231, 76, 28, 113, 23, 219, 250, 71, 209, 210, 205, 97, 32, 159]);
96    let symKey = await genSymKeyByData(keyData);
97    let message = "This is a test";
98    let plainText: cryptoFramework.DataBlob = { data: new Uint8Array(buffer.from(message, 'utf-8').buffer) };
99    let encryptText = await encryptMessagePromise(symKey, plainText);
100    let decryptText = await decryptMessagePromise(symKey, encryptText);
101    if (plainText.data.toString() === decryptText.data.toString()) {
102      console.info('decrypt ok');
103      console.info('decrypt plainText: ' + buffer.from(decryptText.data).toString('utf-8'));
104    } else {
105      console.error('decrypt failed');
106    }
107  }
108  ```
109
110- 同步方法示例：
111
112  ```ts
113  import { cryptoFramework } from '@kit.CryptoArchitectureKit';
114  import { buffer } from '@kit.ArkTS';
115
116
117  function genCcmParamsSpec() {
118    let rand: cryptoFramework.Random = cryptoFramework.createRandom();
119    let ivBlob: cryptoFramework.DataBlob = rand.generateRandomSync(7);
120    let aadBlob: cryptoFramework.DataBlob = rand.generateRandomSync(8);
121    let arr = [0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0]; // 12 bytes
122    let dataTag = new Uint8Array(arr);
123    let tagBlob: cryptoFramework.DataBlob = {
124      data: dataTag
125    };
126    // 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。
127    let ccmParamsSpec: cryptoFramework.CcmParamsSpec = {
128      iv: ivBlob,
129      aad: aadBlob,
130      authTag: tagBlob,
131      algName: "CcmParamsSpec"
132    };
133    return ccmParamsSpec;
134  }
135
136  let ccmParams = genCcmParamsSpec();
137
138  // 加密消息。
139  function encryptMessage(symKey: cryptoFramework.SymKey, plainText: cryptoFramework.DataBlob) {
140    let cipher = cryptoFramework.createCipher('AES128|CCM');
141    cipher.initSync(cryptoFramework.CryptoMode.ENCRYPT_MODE, symKey, ccmParams);
142    let encryptUpdate = cipher.updateSync(plainText);
143    // ccm模式加密doFinal时传入空，获得tag数据，并更新至ccmParams对象中。
144    ccmParams.authTag = cipher.doFinalSync(null);
145    return encryptUpdate;
146  }
147  // 解密消息。
148  function decryptMessage(symKey: cryptoFramework.SymKey, cipherText: cryptoFramework.DataBlob) {
149    let decoder = cryptoFramework.createCipher('AES128|CCM');
150    decoder.initSync(cryptoFramework.CryptoMode.DECRYPT_MODE, symKey, ccmParams);
151    let decryptUpdate = decoder.doFinalSync(cipherText);
152    return decryptUpdate;
153  }
154  function genSymKeyByData(symKeyData: Uint8Array) {
155    let symKeyBlob: cryptoFramework.DataBlob = { data: symKeyData };
156    let aesGenerator = cryptoFramework.createSymKeyGenerator('AES128');
157    let symKey = aesGenerator.convertKeySync(symKeyBlob);
158    console.info('convertKeySync success');
159    return symKey;
160  }
161  function main() {
162    let keyData = new Uint8Array([83, 217, 231, 76, 28, 113, 23, 219, 250, 71, 209, 210, 205, 97, 32, 159]);
163    let symKey = genSymKeyByData(keyData);
164    let message = "This is a test";
165    let plainText: cryptoFramework.DataBlob = { data: new Uint8Array(buffer.from(message, 'utf-8').buffer) };
166    let encryptText = encryptMessage(symKey, plainText);
167    let decryptText = decryptMessage(symKey, encryptText);
168    if (plainText.data.toString() === decryptText.data.toString()) {
169      console.info('decrypt ok');
170      console.info('decrypt plainText: ' + buffer.from(decryptText.data).toString('utf-8'));
171    } else {
172      console.error('decrypt failed');
173    }
174  }
175  ```