Hidden bytes in chat messages

[Eruadarion]

I am looking for a good way to send data via chat to other players, but I don't want it to show as visible strings in the chat window. Only players that parse the chat with a Lua plugin should be able to read the bytes.

I remember there was a thread discussing sending chat messages with additional invisible costum data some time ago. It was an interesting read, but I don't remember the details. It was probably done by exploiting something like the <Select:IID> tags, or something similar. Unfortunately I am not able to find the discussion thread again. I thought it was in context of Thurallor's Blackboard plugin, but it seems like I am mistaken.

Can someone link me the original discussion?

Thanks!

[Eruadarion]

In case anyone is interested, here is my solution to the problem:

import "Turbine";
local print = Turbine.Shell.WriteLine;

local function encodeHiddenString(s)
	if s:len()%8 ~= 0 then error("string length must be divisible by 8") end
	local bytes = {};
	for i=1, s:len() do
		bytes[i] = string.format("%X", s:byte(i));
		if bytes[i]:len() < 2 then bytes[i] = "0"..bytes[i] end
	end
	local selectBegin, selectEnd = "<Select:IID:0x", "><\Select>";
	local result, eightBytes = "", "";
	local j = 1;
	repeat
		eightBytes = "";
		for i=j, j+7 do
			eightBytes = eightBytes..bytes[i];
		end
		result = result..selectBegin..eightBytes..selectEnd;
		j = j+8;
	until j > #bytes
	return result
end

local function decodeHiddenString(s)
	local result = "";
	local byteString = "";
	for bytes in s:gmatch("<Select:IID:0x%x%x%x%x%x%x%x%x%x%x%x%x%x%x%x%x") do
		byteString = byteString..bytes:sub(15, 30);
	end
	for byte in byteString:gmatch('%x%x') do
		local char = string.char(tonumber("0x"..byte));
		result = result..char;
	end
	return result;
end


-- Demo of encoding:
local hiddenMessage = "This is a hidden message";
print("Hello World!"..encodeHiddenString(hiddenMessage));

-- Demo of decoding:
local messageWithHiddenString = "Hello World!<Select:IID:0x5468697320697320><\Select><Select:IID:0x612068696464656E><\Select><Select:IID:0x206D657373616765><\Select>";
print(decodeHiddenString(messageWithHiddenString));

[Hyos]

In case anyone is interested, here is my solution to the problem:

import "Turbine";
local print = Turbine.Shell.WriteLine;

local function encodeHiddenString(s)
	if s:len()%8 ~= 0 then error("string length must be divisible by 8") end
	local bytes = {};
	for i=1, s:len() do
		bytes[i] = string.format("%X", s:byte(i));
		if bytes[i]:len() < 2 then bytes[i] = "0"..bytes[i] end
	end
	local selectBegin, selectEnd = "<Select:IID:0x", "><\Select>";
	local result, eightBytes = "", "";
	local j = 1;
	repeat
		eightBytes = "";
		for i=j, j+7 do
			eightBytes = eightBytes..bytes[i];
		end
		result = result..selectBegin..eightBytes..selectEnd;
		j = j+8;
	until j > #bytes
	return result
end

local function decodeHiddenString(s)
	local result = "";
	local byteString = "";
	for bytes in s:gmatch("<Select:IID:0x%x%x%x%x%x%x%x%x%x%x%x%x%x%x%x%x") do
		byteString = byteString..bytes:sub(15, 30);
	end
	for byte in byteString:gmatch('%x%x') do
		local char = string.char(tonumber("0x"..byte));
		result = result..char;
	end
	return result;
end


-- Demo of encoding:
local hiddenMessage = "This is a hidden message";
print("Hello World!"..encodeHiddenString(hiddenMessage));

-- Demo of decoding:
local messageWithHiddenString = "Hello World!<Select:IID:0x5468697320697320><\Select><Select:IID:0x612068696464656E><\Select><Select:IID:0x206D657373616765><\Select>";
print(decodeHiddenString(messageWithHiddenString));

Have you tried out how much data you can attach in the hidden string? Your example shows 3 times 8bytes, can it be more?

[Eruadarion]

Have you tried out how much data you can attach in the hidden string? Your example shows 3 times 8bytes, can it be more?

Yes, up to 392 bytes (= 49 * 8 bytes) can be encoded as hidden bytes using my function.

If you encode strings longer than 392 characters and then send it as hidden bytes to chat then you will get an error message in LOTRO:
"That text is prohibited because of a content, size, or mixed-alphabet restriction."

EDIT: Typo: you can encode 49 * 8 bytes

[Hyos]

Yes, up to 392 bytes (= 13 * 8 bytes) can be encoded as hidden bytes using my function.

If you encode strings longer than 392 characters and then send it as hidden bytes to chat then you will get an error message in LOTRO:
"That text is prohibited because of a content, size, or mixed-alphabet restriction."

Thank you!

[Thurallor]

A couple of discussions I remember:

• https://www.lotrointerface.com/downl...lackboard.html (see the comments below)
• https://www.lotrointerface.com/forum...ead.php?t=3762

[Eruadarion]

A couple of discussions I remember:

• https://www.lotrointerface.com/downl...lackboard.html (see the comments below)
• https://www.lotrointerface.com/forum...ead.php?t=3762

Thank you! The first link you posted is the thread I was looking for!

So this is my conclusion:
Advantage of using <rgb> tags to send invisible bytes is that you can send up to 955 bytes.
Advantage of using the <Select:IID> tags is that your plugin users won't even see the data when they mouse-over the qickslot button that is used to send the data.