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1# 使用PBKDF2进行密钥派生(C/C++)
2
3<!--Kit: Crypto Architecture Kit-->
4<!--Subsystem: Security-->
5<!--Owner: @zxz--3-->
6<!--Designer: @lanming-->
7<!--Tester: @PAFT-->
8<!--Adviser: @zengyawen-->
9
10对应的算法规格请查看[密钥派生算法规格：PBKDF2](crypto-key-derivation-overview.md#pbkdf2算法)。
11
12## 开发步骤
13
141. 调用[OH_CryptoKdfParams_Create](../../reference/apis-crypto-architecture-kit/capi-crypto-kdf-h.md#oh_cryptokdfparams_create)，指定字符串参数'PBKDF2'，创建密钥派生参数对象。
15
162. 调用[OH_CryptoKdfParams_SetParam](../../reference/apis-crypto-architecture-kit/capi-crypto-kdf-h.md#oh_cryptokdfparams_setparam)，设置PBKDF2所需的参数。示例如下：
17   - CRYPTO_KDF_KEY_DATABLOB：用于生成派生密钥的原始密码。
18   - CRYPTO_KDF_SALT_DATABLOB：盐值。
19   - CRYPTO_KDF_ITER_COUNT_INT：重复运算的次数，需要为正整数。
20
213. 调用[OH_CryptoKdf_Create](../../reference/apis-crypto-architecture-kit/capi-crypto-kdf-h.md#oh_cryptokdf_create)，指定字符串参数'PBKDF2|SHA256'，创建密钥派生函数对象。
22
234. 调用[OH_CryptoKdf_Derive](../../reference/apis-crypto-architecture-kit/capi-crypto-kdf-h.md#oh_cryptokdf_derive)，指定目标密钥的字节长度，进行密钥派生。
24
25```C++
26#include "CryptoArchitectureKit/crypto_architecture_kit.h"
27#include <stdio.h>
28#include <string.h>
29
30static OH_Crypto_ErrCode doTestPbkdf2()
31{
32    // 创建PBKDF2参数对象。
33    OH_CryptoKdfParams *params = nullptr;
34    OH_Crypto_ErrCode ret = OH_CryptoKdfParams_Create("PBKDF2", &params);
35    if (ret != CRYPTO_SUCCESS) {
36        return ret;
37    }
38
39    // 设置密码。
40    const char *password = "123456";
41    Crypto_DataBlob passwordBlob = {
42        .data = reinterpret_cast<uint8_t *>(const_cast<char *>(password)),
43        .len = strlen(password)
44    };
45    ret = OH_CryptoKdfParams_SetParam(params, CRYPTO_KDF_KEY_DATABLOB, &passwordBlob);
46    if (ret != CRYPTO_SUCCESS) {
47        OH_CryptoKdfParams_Destroy(params);
48        return ret;
49    }
50
51    // 设置盐值。
52    const char *salt = "saltstring";
53    Crypto_DataBlob saltBlob = {
54        .data = reinterpret_cast<uint8_t *>(const_cast<char *>(salt)),
55        .len = strlen(salt)
56    };
57    ret = OH_CryptoKdfParams_SetParam(params, CRYPTO_KDF_SALT_DATABLOB, &saltBlob);
58    if (ret != CRYPTO_SUCCESS) {
59        OH_CryptoKdfParams_Destroy(params);
60        return ret;
61    }
62
63    // 设置迭代次数。
64    int iterations = 10000;
65    Crypto_DataBlob iterationsBlob = {
66        .data = reinterpret_cast<uint8_t *>(&iterations),
67        .len = sizeof(int)
68    };
69    ret = OH_CryptoKdfParams_SetParam(params, CRYPTO_KDF_ITER_COUNT_INT, &iterationsBlob);
70    if (ret != CRYPTO_SUCCESS) {
71        OH_CryptoKdfParams_Destroy(params);
72        return ret;
73    }
74
75    // 创建密钥派生函数对象。
76    OH_CryptoKdf *kdfCtx = nullptr;
77    ret = OH_CryptoKdf_Create("PBKDF2|SHA256", &kdfCtx);
78    if (ret != CRYPTO_SUCCESS) {
79        OH_CryptoKdfParams_Destroy(params);
80        return ret;
81    }
82
83    // 派生密钥。
84    Crypto_DataBlob out = {0};
85    uint32_t keyLength = 32; // 生成32字节的密钥。
86    ret = OH_CryptoKdf_Derive(kdfCtx, params, keyLength, &out);
87    if (ret != CRYPTO_SUCCESS) {
88        OH_CryptoKdf_Destroy(kdfCtx);
89        OH_CryptoKdfParams_Destroy(params);
90        return ret;
91    }
92
93    printf("Derived key length: %u\n", out.len);
94
95    // 清理资源。
96    OH_Crypto_FreeDataBlob(&out);
97    OH_CryptoKdf_Destroy(kdfCtx);
98    OH_CryptoKdfParams_Destroy(params);
99    return CRYPTO_SUCCESS;
100}
101```