1# 非匿名密钥证明(C/C++)
2
3在使用本功能前，需申请权限：[ohos.permission.ATTEST_KEY](../AccessToken/permissions-for-system-apps.md#ohospermissionattest_key)。请开发者根据应用的APL等级，参考具体的操作路径[权限申请](../AccessToken/determine-application-mode.md)。
4
5## 在CMake脚本中链接相关动态库
6```txt
7   target_link_libraries(entry PUBLIC libhuks_ndk.z.so)
8```
9
10## 开发步骤
11
121. 确定密钥别名keyAlias，密钥别名最大长度为128字节。
13
142. 初始化参数集：通过[OH_Huks_InitParamSet](../../reference/apis-universal-keystore-kit/_huks_param_set_api.md#oh_huks_initparamset)、[OH_Huks_AddParams](../../reference/apis-universal-keystore-kit/_huks_param_set_api.md#oh_huks_addparams)、[OH_Huks_BuildParamSet](../../reference/apis-universal-keystore-kit/_huks_param_set_api.md#oh_huks_buildparamset)构造参数集paramSet，通过[OH_HUKS_TAG_ALGORITHM](../../reference/apis-universal-keystore-kit/_huks_type_api.md#oh_huks_keyalg)、[OH_HUKS_TAG_KEY_SIZE](../../reference/apis-universal-keystore-kit/_huks_type_api.md#oh_huks_keysize)、[OH_HUKS_TAG_PURPOSE](../../reference/apis-universal-keystore-kit/_huks_type_api.md#oh_huks_keypurpose)分别指定算法、密钥大小、密钥用途属性。
15
163. 生成非对称密钥，具体请参考[密钥生成](huks-key-generation-ndk.md)。
17
184. 将密钥别名与参数集作为参数传入[OH_Huks_AttestKeyItem](../../reference/apis-universal-keystore-kit/_huks_key_api.md#oh_huks_attestkeyitem)方法中，即可证明密钥。
19
20```c++
21#include "huks/native_huks_api.h"
22#include "huks/native_huks_param.h"
23#include <string.h>
24OH_Huks_Result InitParamSet(
25    struct OH_Huks_ParamSet **paramSet,
26    const struct OH_Huks_Param *params,
27    uint32_t paramCount)
28{
29    OH_Huks_Result ret = OH_Huks_InitParamSet(paramSet);
30    if (ret.errorCode != OH_HUKS_SUCCESS) {
31        return ret;
32    }
33    ret = OH_Huks_AddParams(*paramSet, params, paramCount);
34    if (ret.errorCode != OH_HUKS_SUCCESS) {
35        OH_Huks_FreeParamSet(paramSet);
36        return ret;
37    }
38    ret = OH_Huks_BuildParamSet(paramSet);
39    if (ret.errorCode != OH_HUKS_SUCCESS) {
40        OH_Huks_FreeParamSet(paramSet);
41        return ret;
42    }
43    return ret;
44}
45static uint32_t g_size = 4096;
46static uint32_t CERT_COUNT = 4;
47void FreeCertChain(struct OH_Huks_CertChain *certChain, const uint32_t pos)
48{
49    if (certChain == nullptr || certChain->certs == nullptr) {
50        return;
51    }
52    for (uint32_t j = 0; j < pos; j++) {
53        if (certChain->certs[j].data != nullptr) {
54            free(certChain->certs[j].data);
55            certChain->certs[j].data = nullptr;
56        }
57    }
58    if (certChain->certs != nullptr) {
59        free(certChain->certs);
60        certChain->certs = nullptr;
61    }
62}
63int32_t ConstructDataToCertChain(struct OH_Huks_CertChain *certChain)
64{
65    if (certChain == nullptr) {
66        return OH_HUKS_ERR_CODE_ILLEGAL_ARGUMENT;
67    }
68    certChain->certsCount = CERT_COUNT;
69
70    certChain->certs = (struct OH_Huks_Blob *)malloc(sizeof(struct OH_Huks_Blob) * (certChain->certsCount));
71    if (certChain->certs == nullptr) {
72        return OH_HUKS_ERR_CODE_INTERNAL_ERROR;
73    }
74    for (uint32_t i = 0; i < certChain->certsCount; i++) {
75        certChain->certs[i].size = g_size;
76        certChain->certs[i].data = (uint8_t *)malloc(certChain->certs[i].size);
77        if (certChain->certs[i].data == nullptr) {
78            FreeCertChain(certChain, i);
79            return OH_HUKS_ERR_CODE_ILLEGAL_ARGUMENT;
80        }
81    }
82    return 0;
83}
84static struct OH_Huks_Param g_genAttestParams[] = {
85    { .tag = OH_HUKS_TAG_ALGORITHM, .uint32Param = OH_HUKS_ALG_RSA },
86    { .tag = OH_HUKS_TAG_KEY_SIZE, .uint32Param = OH_HUKS_RSA_KEY_SIZE_2048 },
87    { .tag = OH_HUKS_TAG_PURPOSE, .uint32Param = OH_HUKS_KEY_PURPOSE_VERIFY },
88    { .tag = OH_HUKS_TAG_DIGEST, .uint32Param = OH_HUKS_DIGEST_SHA256 },
89    { .tag = OH_HUKS_TAG_PADDING, .uint32Param = OH_HUKS_PADDING_PSS },
90    { .tag = OH_HUKS_TAG_BLOCK_MODE, .uint32Param = OH_HUKS_MODE_ECB },
91};
92#define CHALLENGE_DATA "hi_challenge_data"
93static struct OH_Huks_Blob g_challenge = { sizeof(CHALLENGE_DATA), (uint8_t *)CHALLENGE_DATA };
94static napi_value AttestKey(napi_env env, napi_callback_info info)
95{
96    /* 1.确定密钥别名 */
97    struct OH_Huks_Blob genAlias = {
98        (uint32_t)strlen("test_attest"),
99        (uint8_t *)"test_attest"
100    };
101    static struct OH_Huks_Param g_attestParams[] = {
102        { .tag = OH_HUKS_TAG_ATTESTATION_CHALLENGE, .blob = g_challenge },
103        { .tag = OH_HUKS_TAG_ATTESTATION_ID_ALIAS, .blob = genAlias },
104    };
105    struct OH_Huks_ParamSet *genParamSet = nullptr;
106    struct OH_Huks_ParamSet *attestParamSet = nullptr;
107    OH_Huks_Result ohResult;
108    OH_Huks_Blob certs = { 0 };
109    OH_Huks_CertChain certChain = { &certs, 0 };
110    do {
111        /* 2.初始化密钥参数集 */
112        ohResult = InitParamSet(&genParamSet, g_genAttestParams, sizeof(g_genAttestParams) / sizeof(OH_Huks_Param));
113        if (ohResult.errorCode != OH_HUKS_SUCCESS) {
114            break;
115        }
116        ohResult = InitParamSet(&attestParamSet, g_attestParams, sizeof(g_attestParams) / sizeof(OH_Huks_Param));
117        if (ohResult.errorCode != OH_HUKS_SUCCESS) {
118            break;
119        }
120        ohResult = OH_Huks_GenerateKeyItem(&genAlias, genParamSet, nullptr);
121        if (ohResult.errorCode != OH_HUKS_SUCCESS) {
122            break;
123        }
124
125        (void)ConstructDataToCertChain(&certChain);
126        /* 3.证明密钥 */
127        ohResult = OH_Huks_AttestKeyItem(&genAlias, attestParamSet, &certChain);
128    } while (0);
129    FreeCertChain(&certChain, CERT_COUNT);
130    OH_Huks_FreeParamSet(&genParamSet);
131    OH_Huks_FreeParamSet(&attestParamSet);
132    (void)OH_Huks_DeleteKeyItem(&genAlias, NULL);
133
134    napi_value ret;
135    napi_create_int32(env, ohResult.errorCode, &ret);
136    return ret;
137}
138```
139