# 使用RSA私钥进行编码解码(C/C++)

<!--Kit: Crypto Architecture Kit-->
<!--Subsystem: Security-->
<!--Owner: @zxz--3-->
<!--Designer: @lanming-->
<!--Tester: @PAFT-->
<!--Adviser: @zengyawen-->

**编码**

1. 调用[OH_CryptoAsymKeyGenerator_Create](../../reference/apis-crypto-architecture-kit/capi-crypto-asym-key-h.md#oh_cryptoasymkeygenerator_create)、[OH_CryptoAsymKeyGenerator_Generate](../../reference/apis-crypto-architecture-kit/capi-crypto-asym-key-h.md#oh_cryptoasymkeygenerator_generate)，生成RSA密钥类型为RSA2048、素数个数为2的非对称密钥对（keyPair）。keyPair对象中包括公钥PubKey、私钥PriKey。

   如何生成RSA非对称密钥对，开发者可参考下文示例，并结合[非对称密钥生成和转换规格：RSA](crypto-asym-key-generation-conversion-spec.md#rsa)和[随机生成非对称密钥对(C/C++)](crypto-generate-asym-key-pair-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。

2. 调用[OH_CryptoPrivKeyEncodingParams_Create](../../reference/apis-crypto-architecture-kit/capi-crypto-asym-key-h.md#oh_cryptoprivkeyencodingparams_create)创建参数对象（params），并通过[OH_CryptoPrivKeyEncodingParams_SetParam](../../reference/apis-crypto-architecture-kit/capi-crypto-asym-key-h.md#oh_cryptoprivkeyencodingparams_setparam)设置加密算法和密码。

3. 调用[OH_CryptoPrivKey_Encode](../../reference/apis-crypto-architecture-kit/capi-crypto-asym-key-h.md#oh_cryptoprivkey_encode)，传入参数CRYPTO_PEM/CRYPTO_DER、PKCS1/PCKS8和参数对象（params）生成编码后的私钥字符串。

**解码**

1. 调用[OH_CryptoAsymKeyGenerator_Create](../../reference/apis-crypto-architecture-kit/capi-crypto-asym-key-h.md#oh_cryptoasymkeygenerator_create)生成RSA非对称密钥生成器keyGen。

   如何生成RSA非对称密钥对，开发者可参考下文示例，并结合[非对称密钥生成和转换规格：RSA](crypto-asym-key-generation-conversion-spec.md#rsa)。

2. 调用[OH_CryptoAsymKeyGenerator_SetPassword]，传入编码后的私钥字符串与编码口令。

3. 调用[OH_CryptoAsymKeyGenerator_Convert]，传入参数CRYPTO_PEM和编码后的私钥字符串，返回RSA密钥对。

- 编码示例：
```C++
#include "CryptoArchitectureKit/crypto_architecture_kit.h"

static OH_Crypto_ErrCode doTestPriKeyPkcs1Encoded()
{
    OH_CryptoAsymKeyGenerator *keyGen = nullptr;
    OH_Crypto_ErrCode ret = OH_CryptoAsymKeyGenerator_Create("RSA2048", &keyGen);
    if (ret != CRYPTO_SUCCESS) {
        return ret;
    }
    OH_CryptoKeyPair *keyPair = nullptr;
    ret = OH_CryptoAsymKeyGenerator_Generate(keyGen, &keyPair);
    if (ret != CRYPTO_SUCCESS) {
        OH_CryptoAsymKeyGenerator_Destroy(keyGen);
        return ret;
    }

    OH_CryptoPrivKey *privKey = OH_CryptoKeyPair_GetPrivKey(keyPair);
    if (privKey == nullptr) {
        OH_CryptoKeyPair_Destroy(keyPair);
        OH_CryptoAsymKeyGenerator_Destroy(keyGen);
        return CRYPTO_OPERTION_ERROR;
    }
    OH_CryptoPrivKeyEncodingParams *params = nullptr;
    ret = OH_CryptoPrivKeyEncodingParams_Create(&params);
    if (ret != CRYPTO_SUCCESS) {
        OH_CryptoKeyPair_Destroy(keyPair);
        OH_CryptoAsymKeyGenerator_Destroy(keyGen);
        return ret;
    }

    Crypto_DataBlob password = {(uint8_t *)"1234567890", 10};
    Crypto_DataBlob cipher = {(uint8_t *)"AES-128-CBC", 11};
    ret = OH_CryptoPrivKeyEncodingParams_SetParam(params, CRYPTO_PRIVATE_KEY_ENCODING_PASSWORD_STR, &password);
    if (ret != CRYPTO_SUCCESS) {
        OH_CryptoPrivKeyEncodingParams_Destroy(params);
        OH_CryptoKeyPair_Destroy(keyPair);
        OH_CryptoAsymKeyGenerator_Destroy(keyGen);
        return ret;
    }
    ret = OH_CryptoPrivKeyEncodingParams_SetParam(params, CRYPTO_PRIVATE_KEY_ENCODING_SYMMETRIC_CIPHER_STR, &cipher);
    if (ret != CRYPTO_SUCCESS) {
        OH_CryptoPrivKeyEncodingParams_Destroy(params);
        OH_CryptoKeyPair_Destroy(keyPair);
        OH_CryptoAsymKeyGenerator_Destroy(keyGen);
        return ret;
    }

    Crypto_DataBlob pemData = {0};
    ret = OH_CryptoPrivKey_Encode(privKey, CRYPTO_PEM, "PKCS1", params, &pemData);
    if (ret != CRYPTO_SUCCESS) {
        OH_CryptoPrivKeyEncodingParams_Destroy(params);
        OH_CryptoKeyPair_Destroy(keyPair);
        OH_CryptoAsymKeyGenerator_Destroy(keyGen);
        return ret;
    }
    OH_Crypto_FreeDataBlob(&pemData);
    OH_CryptoPrivKeyEncodingParams_Destroy(params);
    OH_CryptoKeyPair_Destroy(keyPair);
    OH_CryptoAsymKeyGenerator_Destroy(keyGen);
    return ret;
}
```

- 解码示例：
```C++
#include "CryptoArchitectureKit/crypto_architecture_kit.h"
#include <string>

static OH_Crypto_ErrCode doTestConvertPemKeyByPromise()
{
    std::string priKeyPkcs1EncodingStr = "-----BEGIN RSA PRIVATE KEY-----\n"
                                         "Proc-Type: 4,ENCRYPTED\n"
                                         "DEK-Info: AES-128-CBC,815A066131BF05CF87CE610A59CC69AE\n\n"
                                         "7Jd0vmOmYGFZ2yRY8fqRl3+6rQlFtNcMILvcb5KWHDSrxA0ULmJE7CW0DSRikHoA\n"
                                         "t0KgafhYXeQXh0dRy9lvVRAFSLHCLJVjchx90V7ZSivBFEq7+iTozVp4AlbgYsJP\n"
                                         "vx/1sfZD2WAcyMJ7IDmJyft7xnpVSXsyWGTT4f3eaHJIh1dqjwrso7ucAW0FK6rp\n"
                                         "/TONyOoXNfXtRbVtxNyCWBxt4HCSclDZFvS9y8fz9ZwmCUV7jei/YdzyQI2wnE13\n"
                                         "W8cKlpzRFL6BWi8XPrUtAw5MWeHBAPUgPWMfcmiaeyi5BJFhQCrHLi+Gj4EEJvp7\n"
                                         "mP5cbnQAx6+paV5z9m71SKrI/WSc4ixsYYdVmlL/qwAK9YliFfoPl030YJWW6rFf\n"
                                         "T7J9BUlHGUJ0RB2lURNNLakM+UZRkeE9TByzCzgTxuQtyv5Lwsh2mAk3ia5x0kUO\n"
                                         "LHg3Eoabhdh+YZA5hHaxnpF7VjspB78E0F9Btq+A41rSJ6zDOdToHey4MJ2nxdey\n"
                                         "Z3bi81TZ6Fp4IuROrvZ2B/Xl3uNKR7n+AHRKnaAO87ywzyltvjwSh2y3xhJueiRs\n"
                                         "BiYkyL3/fnocD3pexTdN6h3JgQGgO5GV8zw/NrxA85mw8o9im0HreuFObmNj36T9\n"
                                         "k5N+R/QIXW83cIQOLaWK1ThYcluytf0tDRiMoKqULiaA6HvDMigExLxuhCtnoF8I\n"
                                         "iOLN1cPdEVQjzwDHLqXP2DbWW1z9iRepLZlEm1hLRLEmOrTGKezYupVv306SSa6J\n"
                                         "OA55lAeXMbyjFaYCr54HWrpt4NwNBX1efMUURc+1LcHpzFrBTTLbfjIyq6as49pH\n"
                                         "-----END RSA PRIVATE KEY-----\n";

    OH_CryptoAsymKeyGenerator *keyGen = nullptr;
    OH_Crypto_ErrCode ret = OH_CryptoAsymKeyGenerator_Create("RSA2048", &keyGen);
    if (ret != CRYPTO_SUCCESS) {
        return ret;
    }

    OH_CryptoKeyPair *dupKeyPair = nullptr;
    Crypto_DataBlob priKeyPkcs1EncodingData = {};
    priKeyPkcs1EncodingData.data = reinterpret_cast<uint8_t *>(const_cast<char *>(priKeyPkcs1EncodingStr.c_str()));
    priKeyPkcs1EncodingData.len = strlen(priKeyPkcs1EncodingStr.c_str());
    std::string password = "123456";
    ret = OH_CryptoAsymKeyGenerator_SetPassword(keyGen, reinterpret_cast<const unsigned char *>(password.c_str()),
        password.size());
    if (ret != CRYPTO_SUCCESS) {
        OH_CryptoAsymKeyGenerator_Destroy(keyGen);
        return ret;
    }
    ret = OH_CryptoAsymKeyGenerator_Convert(keyGen, CRYPTO_PEM, nullptr, &priKeyPkcs1EncodingData, &dupKeyPair);
    if (ret != CRYPTO_SUCCESS) {
        OH_CryptoAsymKeyGenerator_Destroy(keyGen);
        return ret;
    }
    OH_CryptoKeyPair_Destroy(dupKeyPair);
    OH_CryptoAsymKeyGenerator_Destroy(keyGen);
    return ret;
}
```