基于OpenSSL实现AES/CFB8持续加密的C++技术求助

我最近在做一个用C++复刻Minecraft服务器的副业项目，现在卡在了加密环节。按照Minecraft协议要求，需要用**支持持续更新（无需每个数据包结束后重启）**的AES/CFB8加密算法。网上找的方案要么无法正常运行，要么是命令行实现，求帮忙。

Cipher.h #

class Cipher {
public:
    enum CipherType {
        ENCRYPT,
        DECRYPT
    };

private:
    EVP_CIPHER_CTX* ctx;
    CipherType type;
    bool hasFinished;

public:
    Cipher(const char* key, const char* iv, CipherType type);
    ~Cipher();

    int update(char* in, int inl, char* out);
    int final(char* out);

    int getMinimumBufLength(int size);
};

Cipher.cpp #

Cipher::Cipher(const char* key, const char* iv, CipherType type) : type(type), hasFinished(false)
{
    ctx = EVP_CIPHER_CTX_new();
    EVP_CIPHER_CTX_init(ctx);

    if(type == CipherType::ENCRYPT)
        EVP_EncryptInit_ex(ctx, EVP_aes_256_cfb8(), nullptr, (unsigned char*)key, (unsigned char*)iv);
    else
        EVP_DecryptInit_ex(ctx, EVP_aes_256_cfb8(), nullptr, (unsigned char*)key, (unsigned char*)iv);
    
}

Cipher::~Cipher()
{
    EVP_CIPHER_CTX_free(ctx);
}

int Cipher::getMinimumBufLength(int size)
{
    return type == CipherType::DECRYPT ? size : size + AES_BLOCK_SIZE * 2;
}

int Cipher::update(char* in, int inl, char* out)
{
    int len;
    EVP_CipherUpdate(ctx, (unsigned char*)out, &len, (unsigned char*)in, inl);

    return len;
}

int Cipher::final(char* out)
{
    int len;
    EVP_EncryptFinal_ex(ctx, (unsigned char*)out, &len);

    return len;
}

Cipher-test.cpp #

TEST_CASE("Cipher AES/CFB8") 
{
    char* key = "AAAAAAAAAZEFRGUINJFKDFIVJ";
    char* iv = "AUJVFEUB";
    Cipher encryptionCipher(key, iv, Cipher::CipherType::ENCRYPT);
    Cipher decryptionCipher(key, iv, Cipher::CipherType::DECRYPT);

    std::string data = "Hello World ! This is some soon to be encrypted string !";
    char encData[encryptionCipher.getMinimumBufLength(data.size() + 1)];
    int outLen = encryptionCipher.update(data.data(), data.size() + 1, encData);
    int fLen = encryptionCipher.final(encData + outLen);
    
    CHECK(data != std::string(encData));

    char decData[decryptionCipher.getMinimumBufLength(outLen + fLen)];
    outLen = decryptionCipher.update(encData, outLen + fLen, decData);
    decryptionCipher.final(decData + outLen);

    CHECK(data == std::string(decData));
}

提前感谢！

编辑：我想知道是否需要补充代码来实现加密的“持续”特性。

内容的提问来源于stack exchange，提问作者Lygaen