【安全加密】脱机挂识别：客户端指纹与心跳签名

---登录时的客户端指纹校验
function AntiBot.verifyFingerprint(actor, fp)
    local player = class(actor)
    if not player then return false end
    -- 指纹三要素：版本号、构建哈希、密钥应答
    if fp.version ~= CLIENT_VERSION then
        AntiBot.hit(actor, "版本不符")
        return false
    end
    if fp.buildHash ~= CLIENT_BUILD_HASH then
        AntiBot.hit(actor, "构建哈希不符")
        return false
    end
    -- 挑战应答：只有真客户端能算对的题
    local expect = Crypto.derive(fp.nonce, SERVER_SEED)
    if fp.answer ~= expect then
        AntiBot.hit(actor, "挑战应答失败")
        return false
    end
    return true
end

---心跳包的签名抽检
setontimerex(95, 30)
function AntiBot.heartbeatCheck()
    for _, actor in pairs(Online.all()) do
        if math.random(1, 100) <= 10 then
            -- 10% 抽检：要求客户端签名心跳
            local challenge = Crypto.randomBytes(8)
            AntiBot.sendChallenge(actor, challenge)
            AntiBot.awaitAnswer(actor, challenge, 10)
        end
    end
end

---应答超时与错误的处置
function AntiBot.awaitAnswer(actor, challenge, timeout)
    local s = AntiBot.state[actor:GetUserId()] or
        { fails = 0 }
    s.fails = s.fails + (s.answered and 0 or 1)
    AntiBot.state[actor:GetUserId()] = s
    if s.fails >= 3 then
        QF_KickActor(actor, "客户端校验失败")
        Ban.deviceMark(actor, "脱机挂嫌疑")
    end
end