【高级技巧】消息加密：敏感消息的对称加密传输

local player = class(actor)
local SECRET_KEY = "enc_2026_chuan2"
local function xorCrypt(text, key)
    local out = {}
    for i = 1, #text do
        local b = string.byte(text, i)
        local k = string.byte(key, (i - 1) % #key + 1)
        out[i] = string.char(b ~ k)
    end
    return table.concat(out)
end
local function sendEncrypted(player, msgId, plain)
    local cipher = xorCrypt(plain, SECRET_KEY)
    sendluamsg(player, msgId, #cipher, 0, 0, cipher)
end

local player = class(actor)
local failCnt = {}
local function onCipher(player2, msgId, dataLen, w2, w3, cipher)
    local plain = xorCrypt(cipher, SECRET_KEY)
    local cmd, value = string.match(plain, "([^|]+)|(.+)")
    if cmd == nil then
        failCnt[player2] = (failCnt[player2] or 0) + 1
        if failCnt[player2] >= 5 then
            sendmsg(player, 1, 0, "异常数据包过多，连接已被限制。")
        end
        return
    end
    failCnt[player2] = 0
    if cmd == "changepwd" then
        setplayvar(player, "HUMAN", "PwdStamp", value, true)
        sendmsg(player, 1, 0, "密码修改指令已受理。")
    end
end
SL:RegisterLuaNetMsg(9999, onCipher, nil)