harmony 鸿蒙使用RSA非对称密钥分段加解密(C/C++)

2025-06-16
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使用RSA非对称密钥分段加解密(C/C++)

对应的算法规格请查看非对称密钥加解密算法规格：RSA。

加密

调用OH_CryptoAsymKeyGenerator_Create、OH_CryptoAsymKeyGenerator_Generate，生成RSA密钥类型为RSA1024、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和随机生成非对称密钥对理解。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。

调用OH_CryptoAsymCipher_Create，指定字符串参数’RSA1024|PKCS1’，创建非对称密钥类型为RSA1024、填充模式为PKCS1的Cipher实例，用于完成加解密操作。
调用OH_CryptoAsymCipher_Init，设置模式为加密（CRYPTO_ENCRYPT_MODE），指定加密密钥（keyPair），初始化加密Cipher实例。
多次调用OH_CryptoAsymCipher_Final，传入明文，获取加密后的数据。
- OH_CryptoAsymCipher_Final输出结果可能为NULL，在访问具体数据前，需要先判断结果是否为NULL，避免产生异常。
- 此处将明文按64个字节一组拆分，多次加密。使用1024位密钥，每次将生成128字节密文。

解密

由于RSA算法的Cipher实例不支持重复init操作，需要调用OH_CryptoAsymCipher_Create，重新生成Cipher实例。
调用OH_CryptoAsymCipher_Init，设置模式为解密（CRYPTO_DECRYPT_MODE），指定解密密钥（keyPair）初始化解密Cipher实例。
多次调用OH_CryptoAsymCipher_Final，传入密文，获取解密后的数据。
异步方法示例：

#include "CryptoArchitectureKit/crypto_architecture_kit.h"
#include <algorithm>
#include <vector>

static std::vector<uint8_t> doTestRsaEnc(OH_CryptoKeyPair *keyPair, std::vector<uint8_t> &plainText)
{
    std::vector<uint8_t> cipherText;
    OH_CryptoAsymCipher *cipher = nullptr;
    OH_Crypto_ErrCode ret = OH_CryptoAsymCipher_Create("RSA1024|PKCS1", &cipher);
    if (ret != CRYPTO_SUCCESS) {
        return std::vector<uint8_t>{};
    }

    ret = OH_CryptoAsymCipher_Init(cipher, CRYPTO_ENCRYPT_MODE, keyPair);
    if (ret != CRYPTO_SUCCESS) {
        OH_CryptoAsymCipher_Destroy(cipher);
        return std::vector<uint8_t>{};
    }

    size_t plainTextSplitLen = 64;
    for (size_t i = 0; i < plainText.size(); i += plainTextSplitLen) {
        Crypto_DataBlob in = {};
        in.data = plainText.data() + i;
        if (i + plainTextSplitLen > plainText.size()) {
            in.len = plainText.size() - i;
        } else {
            in.len = plainTextSplitLen;
        }
        Crypto_DataBlob out = {};
        ret = OH_CryptoAsymCipher_Final(cipher, &in, &out);
        if (ret != CRYPTO_SUCCESS) {
            OH_CryptoAsymCipher_Destroy(cipher);
            return std::vector<uint8_t>{};
        }
        cipherText.insert(cipherText.end(), out.data, out.data + out.len);
        OH_Crypto_FreeDataBlob(&out);
    }

    OH_CryptoAsymCipher_Destroy(cipher);
    return cipherText;
}

static std::vector<uint8_t> doTestRsaDec(OH_CryptoKeyPair *keyPair, std::vector<uint8_t> &encryptText)
{
    std::vector<uint8_t> decryptText;
    OH_CryptoAsymCipher *cipher = nullptr;
    OH_Crypto_ErrCode ret = OH_CryptoAsymCipher_Create("RSA1024|PKCS1", &cipher);
    if (ret != CRYPTO_SUCCESS) {
        return std::vector<uint8_t>{};
    }

    ret = OH_CryptoAsymCipher_Init(cipher, CRYPTO_DECRYPT_MODE, keyPair);
    if (ret != CRYPTO_SUCCESS) {
        OH_CryptoAsymCipher_Destroy(cipher);
        return std::vector<uint8_t>{};
    }

    size_t cipherTextSplitLen = 128; // RSA密钥每次加密生成的密文字节长度计算方式：密钥位数/8。
    for (size_t i = 0; i < encryptText.size(); i += cipherTextSplitLen) {
        Crypto_DataBlob in = {};
        in.data = encryptText.data() + i;
        if (i + cipherTextSplitLen > encryptText.size()) {
            in.len = encryptText.size() - i;
        } else {
            in.len = cipherTextSplitLen;
        }
        Crypto_DataBlob out = {};
        ret = OH_CryptoAsymCipher_Final(cipher, &in, &out);
        if (ret != CRYPTO_SUCCESS) {
            OH_CryptoAsymCipher_Destroy(cipher);
            return std::vector<uint8_t>{};
        }
        decryptText.insert(decryptText.end(), out.data, out.data + out.len);
        OH_Crypto_FreeDataBlob(&out);
    }

    OH_CryptoAsymCipher_Destroy(cipher);
    return decryptText;
}

static OH_Crypto_ErrCode doTestRsaEncLongMessage()
{
    OH_CryptoAsymKeyGenerator *keyGen = nullptr;
    OH_Crypto_ErrCode ret = OH_CryptoAsymKeyGenerator_Create("RSA1024", &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;
    }

    std::string message =
        "This is a long plainTest! This is a long plainTest! This is a long plainTest!"
        "This is a long plainTest! This is a long plainTest! This is a long plainTest! This is a long plainTest!"
        "This is a long plainTest! This is a long plainTest! This is a long plainTest! This is a long plainTest!"
        "This is a long plainTest! This is a long plainTest! This is a long plainTest! This is a long plainTest!"
        "This is a long plainTest! This is a long plainTest! This is a long plainTest! This is a long plainTest!"
        "This is a long plainTest! This is a long plainTest! This is a long plainTest! This is a long plainTest!"
        "This is a long plainTest! This is a long plainTest! This is a long plainTest! This is a long plainTest!"
        "This is a long plainTest! This is a long plainTest! This is a long plainTest! This is a long plainTest!";

    std::vector<uint8_t> plainText(message.begin(), message.end());
    std::vector<uint8_t> cipherText = doTestRsaEnc(keyPair, plainText);
    std::vector<uint8_t> decryptText = doTestRsaDec(keyPair, cipherText);

    if ((plainText.size() != decryptText.size())||
        (!std::equal(plainText.begin(), plainText.end(), decryptText.begin()))) {
        OH_CryptoKeyPair_Destroy(keyPair);
        OH_CryptoAsymKeyGenerator_Destroy(keyGen);
        return CRYPTO_OPERTION_ERROR;
    }

    OH_CryptoKeyPair_Destroy(keyPair);
    OH_CryptoAsymKeyGenerator_Destroy(keyGen);
    return CRYPTO_SUCCESS;
}