local bin = require('bin')
local getopt = require('getopt')
local lib14a = require('read14a')
local utils =  require('utils')

copyright = ''
author = "Iceman"
version = 'v1.0.0'
desc = [[
This script calculates mifare keys based on uid diversification for DI. 
Algo not found by me.
]]
example = [[
	 -- if called without, it reads tag uid
	 script run calc_di
	 
	 -- 
	 script run calc_di -u 11223344556677
]]
usage = [[
script run calc_di -h -u <uid>

Arguments:
	-h             : this help
	-u <UID>       : UID
]]

local DEBUG = true
local BAR = '286329204469736E65792032303133'
local MIS = '0A14FD0507FF4BCD026BA83F0A3B89A9'
local bxor = bit32.bxor
--- 
-- A debug printout-function
local function dbg(args)
    if not DEBUG then return end
    if type(args) == "table" then
		local i = 1
		while args[i] do
			dbg(args[i])
			i = i+1
		end
	else
		print("###", args)
	end	
end	
--- 
-- This is only meant to be used when errors occur
local function oops(err)
	print("ERROR: ",err)
	return nil,err
end
--- 
-- Usage help
local function help()
	print(copyright)
	print(author)	
	print(version)	
	print(desc)
	print('Example usage')
	print(example)
end
---
-- Exit message
local function exitMsg(msg)
	print( string.rep('--',20) )
	print( string.rep('--',20) )
	print(msg)
	print()
end
---
-- dumps all keys to file
local function dumptofile(keys)
	dbg('dumping keys to file')

	if utils.confirm('Do you wish to save the keys to dumpfile?') then 
		local destination = utils.input('Select a filename to store to', 'dumpkeys.bin')
		local file = io.open(destination, 'wb')
		if file == nil then 
			print('Could not write to file ', destination)
			return
		end

		-- Mifare Mini has 5 sectors, 
		local key_a = ''
		local key_b = ''
		
		for sector = 0, #keys do
			local keyA, keyB = unpack(keys[sector])
			key_a = key_a .. bin.pack('H', keyA);
			key_b = key_b .. bin.pack('H', keyB);
		end
		file:write(key_a)
		file:write(key_b)
		file:close()
	end
end
---
-- create key
local function keygen(uid)
	local data = MIS..uid..BAR
	local hash = utils.ConvertAsciiToBytes(utils.Sha1Hex(data))
	return string.format("%02X%02X%02X%02X%02X%02X",
		hash[3+1],
		hash[2+1],
		hash[1+1],
		hash[0+1],
		hash[7+1],
		hash[6+1]
		)
end
---
-- print keys
local function printKeys(keys)
	print('|---|----------------|---|----------------|---|')
	print('|sec|key A           |res|key B           |res|')
	print('|---|----------------|---|----------------|---|')
	for sector = 0, #keys do
		local keyA, keyB = unpack(keys[sector])
		print(('|%03d|  %s  | %s |  %s  | %s |'):format(sector, keyA, 1, keyB, 1))
	end	
	print('|---|----------------|---|----------------|---|')
end
---
-- createfull set of keys
local function createKeys(uid)
	local key = keygen(uid)
	local k = {}
	for i = 0,4 do
		k[i] = { key, key }
	end
	return k
end
---
-- main
local function main(args)

	print( string.rep('==', 30) )
	print()
			
	local uid
	local useUID = false
	
	-- Arguments for the script
	for o, a in getopt.getopt(args, 'hu:') do
		if o == "h" then return help() end		
		if o == "u" then uid = a; useUID = true end		
	end

	if useUID then
		-- uid string checks if supplied
		if uid == nil then return oops('empty uid string') end
		if #uid == 0 then return oops('empty uid string') end
		if #uid ~= 14 then return oops('uid wrong length. Should be 7 hex bytes') end
	else
		-- GET TAG UID	
		local tag, err = lib14a.read(false, true)
		if not tag then return oops(err) end
		core.clearCommandBuffer()

		-- simple tag check
		if 0x09 ~= tag.sak then
			if 0x4400 ~= tag.atqa then 
				return oops(('[fail] found tag %s :: looking for Mifare Mini 0.3k'):format(tag.name)) 
			end
		end		
		uid = tag.uid
	end
	
	print('|UID|', uid)	
	
	local keys, err = createKeys( uid )	
	printKeys( keys )
	dumptofile( keys )
end

main(args)