RSA算法

0x0 RSA介绍

RSA是非对称加解密算法，计算耗时，适用于调用次数少，数据量小的场景。比如密钥交换，MD5或Hash做RSA加密。

默认padding方式RSA_PKCS1_PADDING。

0x1 代码实现

h文件

class RsaCrypt{
public:
    enum Mode{
        PUBLIC = 0,
        PRIVATE
    };
public:
    RsaCrypt();
    ~RsaCrypt();

public:
    bool Init(Mode mode, const std::string& key);
    bool Encrypt(const std::string& input, std::string& output);
    bool Decrypt(const std::string& input, std::string& output);

private:
    int rsa_size_;
    bool initialized_;
    Mode mode_;
    BIO* bio_;
    RSA* rsa_;
};

cpp文件

const static int kRsaPadding = RSA_PKCS1_PADDING;

RsaCrypt::RsaCrypt()
: initialized_(false), rsa_size_(0), mode_(RsaCrypt::PRIVATE), rsa_(NULL), bio_(NULL){

}

RsaCrypt::~RsaCrypt() {
    if (bio_) {
        BIO_free_all(bio_);
        bio_ = NULL;
    }
    if (rsa_) {
        RSA_free(rsa_);
        rsa_ = NULL;
    }
}

bool RsaCrypt::Encrypt(const std::string &input, std::string &output) {
    if (!initialized_) {
        LOGE("init not done");
        return false;
    }
    bool result = false;
    if (mode_ == RsaCrypt::PUBLIC) {
        unsigned char* buf = new unsigned char[rsa_size_];
        if (buf) {
            int ret = RSA_public_encrypt(input.length(), (const unsigned char*)input.c_str(), buf, rsa_, kRsaPadding);
            if (ret > 0) {
                output = std::string((char*)buf,ret);
                result = true;
            } else {
                LOGE("RSA_public_encrypt error");
            }
            delete[] buf;
        }
    } else {
        unsigned char* buf = new unsigned char[rsa_size_];
        if (buf) {
            int ret = RSA_private_encrypt(input.length(), (const unsigned char*)input.c_str(), buf, rsa_, kRsaPadding);
            if (ret > 0) {
                output = std::string((char*)buf,ret);
                result = true;
            } else {
                LOGE("RSA_public_encrypt error");
            }
            delete[] buf;
        }
    }
    return result;
}

bool RsaCrypt::Decrypt(const std::string &input, std::string &output) {
    if (!initialized_) {
        LOGE("init not done");
        return false;
    }
    bool result = false;
    if (mode_ == RsaCrypt::PUBLIC) {
        unsigned char* buf = new unsigned char[rsa_size_];
        if (buf) {
            int ret = RSA_public_decrypt(input.length(), (const unsigned char*)input.c_str(), buf, rsa_, kRsaPadding);
            if (ret > 0) {
                output = std::string((char*)buf,ret);
                result = true;
            } else {
                LOGE("RSA_public_decrypt error");
            }
            delete[] buf;
        }
    } else {
        unsigned char* buf = new unsigned char[rsa_size_];
        if (buf) {
            int ret = RSA_private_decrypt(input.length(), (const unsigned char*)input.c_str(), buf, rsa_, kRsaPadding);
            if (ret > 0) {
                output = std::string((char*)buf,ret);
                result = true;
            } else {
                LOGE("RSA_private_decrypt error");
            }
            delete[] buf;
        }
    }
    return result;
}

bool RsaCrypt::Init(RsaCrypt::Mode mode, const std::string &key) {
    if (initialized_) {
        LOGE("init already done");
        return true;
    }
    mode_ = mode;
    bio_ = BIO_new_mem_buf((const void*)key.c_str(), -1);
    if (bio_) {
        if (mode_ == RsaCrypt::PRIVATE) {
            PEM_read_bio_RSAPrivateKey(bio_, &rsa_, NULL, NULL);
        } else {
            //PEM_read_bio_RSAPublicKey(bio_, &rsa_, NULL, NULL);
            PEM_read_bio_RSA_PUBKEY(bio_, &rsa_, NULL, NULL);
        }
    }
    if (!rsa_) {
        if (bio_) {
            LOGE("rsa key error");
            BIO_free_all(bio_);
            bio_ = NULL;
        }
    } else {
        rsa_size_ = RSA_size(rsa_);
        initialized_ = true;
    }
    return initialized_;
}

0x2 参数key的格式

        const char pub[]="-----BEGIN PUBLIC KEY-----\n"
                "MIIBIjANBgkqhkiG9w0BAQEFAAOCAQ8AMIIBCgKCAQEA56iwzdromMYI3T4DTtH8\n"
                "H5g1WNRdfLJJs94rRLhr/wMDpmCYQx+7VQsbsqO6juxwOhALQ80wdAIZE0MjBeMa\n"
                "svmAy0qhSSTRJ5s0/DLNf4nvmX6aQGHJAAD/411t9o88YLMMBKpXqQrdV3wXBWZE\n"
                "5qISF6zpEa9e4YXCaGOrRWIrbgjBm1kWSL/H+YKj8D6zzmxooFqSHxnQhyyVv58+\n"
                "aPZOYpkcAFC/A5A9twxl1wBtyxUZmynC3Nj2H+03VveYHyg4R3A22WemFUu1T5S6\n"
                "FpyiMXXI6jfoO6/Oiq/VYg+IciCAs35/rljuyn9LpwFuzPVTJRiFSaTvgkifz9yh\n"
                "qwIDAQAB\n"
                "-----END PUBLIC KEY-----";

        const char priKey[]="-----BEGIN RSA PRIVATE KEY-----\n"
                "MIIEpgIBAAKCAQEA56iwzdromMYI3T4DTtH8H5g1WNRdfLJJs94rRLhr/wMDpmCY\n"
                "Qx+7VQsbsqO6juxwOhALQ80wdAIZE0MjBeMasvmAy0qhSSTRJ5s0/DLNf4nvmX6a\n"
                "QGHJAAD/411t9o88YLMMBKpXqQrdV3wXBWZE5qISF6zpEa9e4YXCaGOrRWIrbgjB\n"
                "m1kWSL/H+YKj8D6zzmxooFqSHxnQhyyVv58+aPZOYpkcAFC/A5A9twxl1wBtyxUZ\n"
                "mynC3Nj2H+03VveYHyg4R3A22WemFUu1T5S6FpyiMXXI6jfoO6/Oiq/VYg+IciCA\n"
                "s35/rljuyn9LpwFuzPVTJRiFSaTvgkifz9yhqwIDAQABAoIBAQCcSzu+J0t2h2XD\n"
                "nussao/n4RFc9Sp9zuva5rHak3KJgscboWAZKXeCURRG2iAr/WlaQyjWfcGLAz9X\n"
                "t5wRhL+msJ8siRV3+9cBGb4NyVjMC4wTy07W0SKDVilOhOKDzu+1bhdVrnemHSZo\n"
                "t9fwVKd30zDRuF8nB2LEVTJsq5IKJID7PjifPHR0IdiX8LLqdwHmS+3l/yzL2vHC\n"
                "O1BLIisrmOJ5d73WAqa3iIqSSNo7XD46R9/52O5Pt6fN9p/yH+wS9lgHT8WqJdCP\n"
                "dNPB13hz0JEi8slnQ6+I7Jv3Mm/19b9oO+KxViI6Vwuf29b290N/IGHPblvLyHnP\n"
                "FF+0feDBAoGBAPVtHZ78mLMuZux20DbD6CDKXh9KRFgl9jXeHfrjCEWkgsYuuRlI\n"
                "EPeRDC0h0RNqGFWwFL3lvUx4vmUWG3nRUW1QzbXmTvshpnLWyzn4gZc0+dhCpYOe\n"
                "A8mnAo1KAXrJTg4OMaHY4+AUpPb+3C2NbEhVrg8CmqJz/EJdti/qaymnAoGBAPGj\n"
                "uyx0S3V84CANCqVWtUT8SXTpEi48t/mJQORI6dg3/c17GXL2IJRkZKYgrPXbheQB\n"
                "lXFsARijtdPXwjCGh6duajGdQHga/oJ2v0U/kqL6aQBh8AUK6XYwGKNg7X2EqsBL\n"
                "yEVHfjW27B4Do4qPhMkk8t6Dks2byGsMrrK6bYBdAoGBAIYoxKVxLUPdnLOsaztU\n"
                "siKinPr7zQpmjgV6SucnjhEL0dTmG5bfVy8NohtVvgWf3HeSznPUDzurUWDOyew4\n"
                "aQuZvSmvIQOUrHlgQy2IU8bFVcJLBFFDYoyr9/AmQVLOkhWK2sS/XCnU/yxpuxBH\n"
                "m6aa95AK+17Milv5ACuHOFdHAoGBAOvaxHc/i+fBW4HtONbpK0WKeqiCVhyLZ4dJ\n"
                "UO2Bvb4t6K0H2m87jdFJrHP6sNfIzYcfhJ6QrQE/ydpcXk6/AOmL/FsxAhw5PPJa\n"
                "tZcB1j797D9TWNOTMw0JJQNTOHurYn8PeQsmHSqQwScKpjY4n4M1bVmDU2cdByJ1\n"
                "3o7VKMyBAoGBAO+GspzqWxKDsxwrd2PqAVLtJqpVCNmGVQNutFi98484l+0WVlju\n"
                "tVMu2pQ2c8JOdAiTEyZQJRx/tS6U46C/N96OPKppBC8/wbqYoCD9LyxAshqVWi10\n"
                "6jn+RB4INmgbYc1vZuG7846Xj0h6dsBfdaGDapTqsm3eQKTfb+QGNekf\n"
                "-----END RSA PRIVATE KEY-----";