xref: /docs/en/application-dev/security/UniversalKeystoreKit/huks-import-key-in-plaintext-ndk.md (revision e41f4b71)

# Importing a Key in Plaintext (C/C++)


This topic walks you through on how to import an ECC key. For details about the scenarios and supported algorithm specifications, see [Supported Algorithms](huks-key-import-overview.md#supported-algorithms).

## Add the dynamic library in the CMake script.
```txt
   target_link_libraries(entry PUBLIC libhuks_ndk.z.so)
```

## How to Develop

1. Set the alias **keyAlias** of the key to import.
   The key alias cannot exceed 128 bytes.

2. Encapsulate the key property set and key material. Construct the key property set **paramSet** using [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), and [OH_Huks_BuildParamSet](../../reference/apis-universal-keystore-kit/_huks_param_set_api.md#oh_huks_buildparamset).
   - ** paramSet** must contain [OH_Huks_KeyAlg](../../reference/apis-universal-keystore-kit/_huks_type_api.md#oh_huks_keyalg), [OH_Huks_KeySize](../../reference/apis-universal-keystore-kit/_huks_type_api.md#oh_huks_keysize), and [OH_Huks_KeyPurpose](../../reference/apis-universal-keystore-kit/_huks_type_api.md#oh_huks_keypurpose).
   - The key material must comply with the [HUKS key material format](huks-concepts.md#key-material-format).

3. Use [OH_Huks_ImportKeyItem](../../reference/apis-universal-keystore-kit/_huks_key_api.md#oh_huks_importkeyitem) to import the key.

```c++
/* Import an ECC key in plaintext. */
#include "huks/native_huks_api.h"
#include "huks/native_huks_param.h"
#include <string.h>
OH_Huks_Result InitParamSet(struct OH_Huks_ParamSet **paramSet, const struct OH_Huks_Param *params,
                            uint32_t paramCount) {
    OH_Huks_Result ret = OH_Huks_InitParamSet(paramSet);
    if (ret.errorCode != OH_HUKS_SUCCESS) {
        return ret;
    }
    ret = OH_Huks_AddParams(*paramSet, params, paramCount);
    if (ret.errorCode != OH_HUKS_SUCCESS) {
        OH_Huks_FreeParamSet(paramSet);
        return ret;
    }
    ret = OH_Huks_BuildParamSet(paramSet);
    if (ret.errorCode != OH_HUKS_SUCCESS) {
        OH_Huks_FreeParamSet(paramSet);
        return ret;
    }
    return ret;
}
struct OH_Huks_Param g_testGenerateKeyParam[] = {{.tag = OH_HUKS_TAG_ALGORITHM, .uint32Param = OH_HUKS_ALG_ECC},
                                                 {.tag = OH_HUKS_TAG_PURPOSE, .uint32Param = OH_HUKS_KEY_PURPOSE_AGREE},
                                                 {.tag = OH_HUKS_TAG_KEY_SIZE, .uint32Param = OH_HUKS_ECC_KEY_SIZE_256},
                                                 {.tag = OH_HUKS_TAG_DIGEST, .uint32Param = OH_HUKS_DIGEST_NONE}};
static napi_value GenerateKey(napi_env env, napi_callback_info info) {
    const char *alias = "test_generate";
    struct OH_Huks_Blob aliasBlob = {.size = (uint32_t)strlen(alias), .data = (uint8_t *)alias};
    struct OH_Huks_ParamSet *testGenerateKeyParamSet = nullptr;
    struct OH_Huks_Result ohResult;
    do {
        ohResult = InitParamSet(&testGenerateKeyParamSet, g_testGenerateKeyParam,
                                sizeof(g_testGenerateKeyParam) / sizeof(OH_Huks_Param));
        if (ohResult.errorCode != OH_HUKS_SUCCESS) {
            break;
        }
        ohResult = OH_Huks_GenerateKeyItem(&aliasBlob, testGenerateKeyParamSet, nullptr);
    } while (0);
    OH_Huks_FreeParamSet(&testGenerateKeyParamSet);
    napi_value ret;
    napi_create_int32(env, ohResult.errorCode, &ret);
    return ret;
}
static napi_value ImportKey(napi_env env, napi_callback_info info) {
    (void)GenerateKey(env, info);
    const char *alias = "test_generate";
    struct OH_Huks_Blob aliasBlob = {.size = (uint32_t)strlen(alias), .data = (uint8_t *)alias};
    uint8_t pubKey[OH_HUKS_ECC_KEY_SIZE_256] = {0};
    struct OH_Huks_Blob publicKey = {OH_HUKS_ECC_KEY_SIZE_256, pubKey};
    struct OH_Huks_ParamSet *testImportKeyParamSet = nullptr;
    struct OH_Huks_Result ohResult;
    do {
        ohResult = InitParamSet(&testImportKeyParamSet, g_testGenerateKeyParam,
                                sizeof(g_testGenerateKeyParam) / sizeof(OH_Huks_Param));
        if (ohResult.errorCode != OH_HUKS_SUCCESS) {
            break;
        }
        ohResult = OH_Huks_ExportPublicKeyItem(&aliasBlob, testImportKeyParamSet, &publicKey);
        if (ohResult.errorCode != OH_HUKS_SUCCESS) {
            break;
        }
        /* 4. Import Key */
        char newKey[] = "test_import";
        struct OH_Huks_Blob newKeyAlias = {.size = (uint32_t)strlen(newKey), .data = (uint8_t *)newKey};
        ohResult = OH_Huks_ImportKeyItem(&newKeyAlias, testImportKeyParamSet, &publicKey);
    } while (0);
    OH_Huks_FreeParamSet(&testImportKeyParamSet);
    napi_value ret;
    napi_create_int32(env, ohResult.errorCode, &ret);
    return ret;
}
```