使用工具

  • Qt Creator 16.0.1 (Community)
  • vscode

具体逻辑

本次应用场景为qt和服务端互相交换非对称加密后的对称密钥，用于弥补rsa加密字节容量过少的缺点，简称混合加密

图片

实现代码

qt客户端

  • 定义指针，可复用性
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EVP_PKEY* JsonCrypto::loadPublicKey() {
    QFile file(m_pubPath);
    if (!file.open(QIODevice::ReadOnly)) return nullptr;
    QByteArray data = file.readAll();
    BIO *bio = BIO_new_mem_buf(data.constData(), data.size());
    EVP_PKEY *pkey = PEM_read_bio_PUBKEY(bio, nullptr, nullptr, nullptr);
    BIO_free(bio);
    return pkey;
}

EVP_PKEY* JsonCrypto::loadPrivateKey() {
    QFile file(m_privPath);
    if (!file.open(QIODevice::ReadOnly)) return nullptr;
    QByteArray data = file.readAll();
    BIO *bio = BIO_new_mem_buf(data.constData(), data.size());
    EVP_PKEY *pkey = PEM_read_bio_PrivateKey(bio, nullptr, nullptr, nullptr);
    BIO_free(bio);
    return pkey;
}

  • 生成非对称密钥(rsa)

    实现功能如下

    • 返回base64编码后的密钥，方便传输
    • 保存客户端生成的私钥
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QString JsonCrypto::generateKey() {
    EVP_PKEY *pkey = EVP_RSA_gen(2048);
    if (!pkey) return {};

    // Save private key
    QFile privFile(m_privPath);
    if (!privFile.open(QIODevice::WriteOnly)) {
        EVP_PKEY_free(pkey);
        return {};
    }
    BIO *privBio = BIO_new(BIO_s_mem());
    PEM_write_bio_PrivateKey(privBio, pkey, nullptr, nullptr, 0, nullptr, nullptr);
    BUF_MEM *privPtr;
    BIO_get_mem_ptr(privBio, &privPtr);
    privFile.write(privPtr->data, static_cast<int>(privPtr->length));
    privFile.close();
    BIO_free(privBio);

    // Get public key
    BIO *pubBio = BIO_new(BIO_s_mem());
    PEM_write_bio_PUBKEY(pubBio, pkey);
    BUF_MEM *pubPtr;
    BIO_get_mem_ptr(pubBio, &pubPtr);
    QByteArray pubPem(pubPtr->data, static_cast<int>(pubPtr->length));
    BIO_free(pubBio);
    EVP_PKEY_free(pkey);

    QByteArray b64Data = pubPem.toBase64();
    return QString::fromLatin1(b64Data);
}
  • 报错客户端生成的私钥
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