Yeah i agree this is a good idea.

You should use the fs API, probably the fs.exists() function.

if fs.exists("/disk/file") then
  print("Success")
end

You can iterate through all values in a table by using pairs()

test_table = { ["0,0,0"] = "foo", ["0,1,1"] = "bar" }
for key, value in pairs(test_table) do
    print(key, value)
end
--output
--[0,0,0]  foo
--[0,1,1]  bar

if test_table had tables instead of the strings foo and bar, pairs() would not go into those tables.
pairs() only iterates through the top table.

if you just want the first* item of a table you can use

first = next(test_table)

I do not recommend this as it is unreliable under some conditions.

* tables may act in unexpected ways due to the fact that they do not have an specific order in the same way that other languages has them.

If you want realism, i don't think minecraft is the correct place to look.

I don't think 8 more pieces of redstone will fix that.

If removing optifine works, try toying around with the optifine options to see if you can fix it without removing optifine, but only if you want to keep optifine.

blackvice, on 05 March 2017 - 11:22 AM, said:

I linux works on virtually any device. And ubuntu or arch anywhere help with setting drivers up, but ubuntu is easier for a linux beginner.

You should check the version of java, also press f3 and take a screenshot, that will give us more information.

Also what OS are you using?

<snip>

If you would like more features or help, posting the source code would help us understand what you mean.

You can do this using "pastebin put <programName>" and then go to http://pastebin.com/<the weird Numbers and letters it writes>. You will then see your source code and can send us a link.

Just to be sure, the error is thrown by the Monitor setup computer, right?

I think the point of the redstone is just to make sure that the player has to get that far in the game, but i don't think dan200 had game balance as the main focus of this mod.

Well this is no normal lua error, this a an error in the computercraft mod, or other mods. I will look into how this happend.

Does this happen when anything specific happens, or is it a general error?

Incinirate, on 20 March 2017 - 12:51 AM, said:

When it's done you should make it work over rednet.

Dave-ee Jones, on 29 March 2017 - 10:36 PM, said:

Doing security through obscurity is never a good idea, rolling codes, using the Blink API recommended above or using a challenge response system would all be very viable solutions.

KingofGamesYami, on 30 March 2017 - 01:11 PM, said:

Definitely the simplest and probably the most reliable option.


If you want to use a disk, i would simply store a password in the disk then make the computer read it. Potentially using a disk event.
Then simply use the filesystem API to read a file on the disk, and send the key in that file to the door computer via any of the methods we have mentioned above.
Then the door computer validates this and opens the door.

You have quite a few extra end's, you only need an end when you want to end an if statement or loop entirely

while true do
  input = read("*")
  if input == password then
	--do correct password stuff
  elseif input == "backdoor" then
	--do backdoor stuff
  else
	--do wrong password stuff
  end
end

Notice how every time the indentation go a level down, there is an end. There is no end before the else and elseif statment because they are part of the if statement, they build onto it.

Also note how the elseif comes before the else, this is because if the else was before, the computer would check to see if the input is the same as the password and if not then it would check the the next statement, if this statment is an else it would do that code and be done, but if it is an elseif it would check that code and then continue depending on the statment.

Generaly if statments go as follows,
first an if, any amount of elseif's (0 is an amount), optionally an else, an end

A more detailed version of the previous would be as follows
first an if, a condition and a then, any amount of elseif's, a condition and a then (0 is an amount), optionally an else, an end

I don't know if that made sense just ask if it didn't.

using 'read ("*")' is valid, but weird if the rest of the code is without a space between the function name and the parentheses

Dave-ee Jones, on 29 March 2017 - 02:17 AM, said:

The problem with this is that if anyone is listening while you transfer your secret password they get your password, and can then use it to do whatever you use your password for.

The crypto required is doesn't really need to be that advanced if it's just a simple authentication.

Let's say there is a secret key that only the server and client know, any other listener doesn't have this key.
First the client says that it want's to authenticate so it requests a salt from the server.
The server sends a randomly generated salt (You have to properly generate this using a good randomizer since lua's is horrible)
Then the client takes it's key and concatenates the salt to it, and hashes the result. It then sends that hash to the server.
The in the meanwhile takes it's own secret key and concatenates the salt to it, and hashes the result.
It then receives the hash from the client and checks to see if they match, if they do, the client has the proper key.

Note that the key was never sent at any time, the only form that was sent was the hash and the salt.
This allows a listener to produce a brute force attack, but using a long enough random key and a good hashing algorithm (brcrypt), this bruteforce could last longer than the lifespan of the universe.

The only way to get this key would be to compromise the server or client.

You could also, as the OP states, store the key on a disk instead of the client, which means that the client is now secured, but instead you have to protect the disk.

EDIT: Here is a, according to the post, cryptographically secure random number generator.

I'm working on adding a generic tag where one can paste a full url and forget about the rest, but surprisingly i am having more problems with this than the pastebin and github tag combined.

You're welcome

If you want TigerMeister and Tigernr2 to be passwords and usernames you have to use them as string. Use this

master = "TigerMeister"
password = "Tigernr2"

Also instead of

if master == password then

you should compare user to master and pass to password as so

if user == master and pass == password then

Using more descriptive variable names such as master_username, master_password, read_user, read_password can ensure that these types of errors don't happen

If you have any other errors, please write down the error line number and message, or explain what happens

You're welcome

you want to use

file = fs.open("file_path_here", "a")

"a" being the important part, this appends to the end of the file.

you can then use

file.writeLine("This line is now appended!")

to append to the end of the file.