Test Encrypter

tArgs = { ... }

function printUsage()
	print("Usage: " ..shell.getRunningProgram().. " <encrypt/decrypt> [filename] [password]")
end

if #tArgs < 1 then
	printUsage()
	return
end

function encrypt( str, password )
	local mainString = ""

	local passwordLocation = 1
	for i=1,#str do
		local str1 = string.byte( string.sub(str, i, i) ) + string.byte( string.sub(password, passwordLocation, passwordLocation) )

		if passwordLocation == #password then
			passwordLocation = 1
		else
			passwordLocation = passwordLocation +1
		end

		if i == 1 then
			mainString = str1
		else
			mainString = mainString .. "/" ..str1
		end
	end

	return mainString
end

function decrypt( str, password )
	tWords = {}
	for match in string.gmatch(str, "[^/\t]+") do
		table.insert( tWords, match )
	end

	local dahString = ""
	local passwordLocation = 1
	for i=1,#tWords do
		local anodahwunbitezdahdust = tonumber(tWords[i]) - string.byte( string.sub(password, passwordLocation, passwordLocation) )

		dahString = dahString .. string.char( anodahwunbitezdahdust )

		passwordLocation = passwordLocation +1
		if passwordLocation == #password then
			passwordLocation = 1
		end
	end

	return dahString
end

if string.lower(tArgs[1]) == "encrypt" and fs.exists(tArgs[2]) and tArgs[3] then
	file = fs.open(tArgs[2], "r")
	local endResult = {}
	local characters = 0
	line = file.readLine()
	while line do
		characters = characters + #line
		table.insert(endResult, encrypt(line, tArgs[3]))
		line = file.readLine()
	end

	local resultName = characters + math.random(1,10)
	results = fs.open("result_" ..resultName, "w")
	for i=1,#endResult do
		results.write(endResult[i])
	end

	results.close()
	print("Encrypted " ..characters.. " characters. ")
	print("Password: " ..tArgs[3])
	print("Result file: result_" ..resultName)

elseif string.lower(tArgs[1]) == "decrypt" and fs.exists(tArgs[2]) and tArgs[3] then


	local resultNum = math.random(1,999)
	file = fs.open("result_" ..resultNum, "w")
	fileRead = fs.open( tArgs[2], "r")
	line = fileRead.readLine()
	local endResult = decrypt( line, tArgs[3] );
	file.write(endResult)
	fileRead.close()
	file.close()

	print("Decrypted. Saved as: ")
	print("result_" ..resultNum)
else
	printUsage()
end