1# 使用AES对称密钥（CBC模式）加解密(C/C++)
2
3
4对应的算法规格请查看[对称密钥加解密算法规格：AES](crypto-sym-encrypt-decrypt-spec.md#aes)。
5
6
7## 在CMake脚本中链接相关动态库
8```txt
9   target_link_libraries(entry PUBLIC libohcrypto.so)
10```
11
12## 开发步骤
13
14
15**加密**
16
171. 调用[OH_CryptoSymKeyGenerator_Create](../../reference/apis-crypto-architecture-kit/_crypto_sym_key_api.md#oh_cryptosymkeygenerator_create)、[OH_CryptoSymKeyGenerator_Generate](../../reference/apis-crypto-architecture-kit/_crypto_sym_key_api.md#oh_cryptosymkeygenerator_generate)，生成密钥算法为AES、密钥长度为128位的对称密钥（OH_CryptoSymKey）。
18
19   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-ndk.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。
20
212. 调用[OH_CryptoSymCipher_Create](../../reference/apis-crypto-architecture-kit/_crypto_sym_cipher_api.md#oh_cryptosymcipher_create)，指定字符串参数'AES128|CBC|PKCS7'，创建对称密钥类型为AES128、分组模式为CBC、填充模式为PKCS7的Cipher实例，用于完成加解密操作。
22
233. 调用[OH_CryptoSymCipherParams_Create](../../reference/apis-crypto-architecture-kit/_crypto_sym_cipher_api.md#oh_cryptosymcipherparams_create)创建参数对象，调用[OH_CryptoSymCipherParams_SetParam](../../reference/apis-crypto-architecture-kit/_crypto_sym_cipher_api.md#oh_cryptosymcipherparams_setparam)设置对应的加密参数。
24
254. 调用[OH_CryptoSymCipher_Init](../../reference/apis-crypto-architecture-kit/_crypto_sym_cipher_api.md#oh_cryptosymcipher_init)，设置模式为加密（CRYPTO_ENCRYPT_MODE），指定加密密钥（OH_CryptoSymKey）和CBC模式对应的加密参数（OH_CryptoSymCipherParams），初始化加密Cipher实例。
26
275. 加密内容较短时，可以不调用[OH_CryptoSymCipher_Update](../../reference/apis-crypto-architecture-kit/_crypto_sym_cipher_api.md#oh_cryptosymcipher_update)，直接调用[OH_CryptoSymCipher_Final](../../reference/apis-crypto-architecture-kit/_crypto_sym_cipher_api.md#oh_cryptosymcipher_final)，获取加密后的数据。
28
296. 调用[OH_CryptoSymKeyGenerator_Destroy](../../reference/apis-crypto-architecture-kit/_crypto_sym_key_api.md#oh_cryptosymkeygenerator_destroy)、[OH_CryptoSymCipher_Destroy](../../reference/apis-crypto-architecture-kit/_crypto_sym_cipher_api.md#oh_cryptosymcipher_destroy)、[OH_CryptoSymCipherParams_Destroy](../../reference/apis-crypto-architecture-kit/_crypto_sym_cipher_api.md#oh_cryptosymcipherparams_destroy)销毁各对象。
30
31
32**解密**
33
34
351. 调用[OH_CryptoSymCipher_Init](../../reference/apis-crypto-architecture-kit/_crypto_sym_cipher_api.md#oh_cryptosymcipher_init)，设置模式为解密（CRYPTO_DECRYPT_MODE），指定解密密钥（OH_CryptoSymKey）和CBC模式对应的解密参数（OH_CryptoSymCipherParams），初始化解密Cipher实例。
36
372. 解密内容较短时，可以不调用[OH_CryptoSymCipher_Update](../../reference/apis-crypto-architecture-kit/_crypto_sym_cipher_api.md#oh_cryptosymcipher_update)，直接调用[OH_CryptoSymCipher_Final](../../reference/apis-crypto-architecture-kit/_crypto_sym_cipher_api.md#oh_cryptosymcipher_final)，获取解密后的数据。
38
39
40
41```c++
42#include "CryptoArchitectureKit/crypto_common.h"
43#include "CryptoArchitectureKit/crypto_sym_cipher.h"
44#include <string.h>
45
46static OH_Crypto_ErrCode doTestAesCbc()
47{
48    OH_CryptoSymKeyGenerator *genCtx = nullptr;
49    OH_CryptoSymCipher *encCtx = nullptr;
50    OH_CryptoSymCipher *decCtx = nullptr;
51    OH_CryptoSymKey *keyCtx = nullptr;
52    OH_CryptoSymCipherParams *params = nullptr;
53    Crypto_DataBlob outUpdate = {.data = nullptr, .len = 0};
54    Crypto_DataBlob decUpdate = {.data = nullptr, .len = 0};
55    char *plainText = const_cast<char *>("this is test!");
56    Crypto_DataBlob msgBlob = {.data = (uint8_t *)(plainText), .len = strlen(plainText)};
57    uint8_t iv[16] = {1, 2, 4, 12, 3, 4, 2, 3, 3, 2, 0, 4, 3, 1, 0, 10}; // iv使用安全随机数生成
58    Crypto_DataBlob ivBlob = {.data = iv, .len = sizeof(iv)};
59    // 生成对称密钥
60    OH_Crypto_ErrCode ret;
61    ret = OH_CryptoSymKeyGenerator_Create("AES128", &genCtx);
62    if (ret != CRYPTO_SUCCESS) {
63        goto end;
64    }
65    ret = OH_CryptoSymKeyGenerator_Generate(genCtx, &keyCtx);
66    if (ret != CRYPTO_SUCCESS) {
67        goto end;
68    }
69
70    // 设置参数
71    ret = OH_CryptoSymCipherParams_Create(&params);
72    if (ret != CRYPTO_SUCCESS) {
73        goto end;
74    }
75    ret = OH_CryptoSymCipherParams_SetParam(params, CRYPTO_IV_DATABLOB, &ivBlob);
76    if (ret != CRYPTO_SUCCESS) {
77        goto end;
78    }
79
80    // 加密
81    ret = OH_CryptoSymCipher_Create("AES128|CBC|PKCS7", &encCtx);
82    if (ret != CRYPTO_SUCCESS) {
83        goto end;
84    }
85    ret = OH_CryptoSymCipher_Init(encCtx, CRYPTO_ENCRYPT_MODE, keyCtx, params);
86    if (ret != CRYPTO_SUCCESS) {
87        goto end;
88    }
89    ret = OH_CryptoSymCipher_Final(encCtx, &msgBlob, &outUpdate);
90    if (ret != CRYPTO_SUCCESS) {
91        goto end;
92    }
93
94    // 解密
95    ret = OH_CryptoSymCipher_Create("AES128|CBC|PKCS7", &decCtx);
96    if (ret != CRYPTO_SUCCESS) {
97        goto end;
98    }
99    ret = OH_CryptoSymCipher_Init(decCtx, CRYPTO_DECRYPT_MODE, keyCtx, params);
100    if (ret != CRYPTO_SUCCESS) {
101        goto end;
102    }
103    ret = OH_CryptoSymCipher_Final(decCtx, &outUpdate, &decUpdate);
104    if (ret != CRYPTO_SUCCESS) {
105        goto end;
106    }
107
108end:
109    OH_CryptoSymCipherParams_Destroy(params);
110    OH_CryptoSymCipher_Destroy(encCtx);
111    OH_CryptoSymCipher_Destroy(decCtx);
112    OH_CryptoSymKeyGenerator_Destroy(genCtx);
113    OH_CryptoSymKey_Destroy(keyCtx);
114    OH_Crypto_FreeDataBlob(&outUpdate);
115    OH_Crypto_FreeDataBlob(&decUpdate);
116    return ret;
117}
118```