local function _W(f) local e=setmetatable({}, {__index = _ENV or getfenv()}) if setfenv then setfenv(f, e) end return f(e) or e end
local bit=_W(function(_ENV, ...)
--[[
	This bit API is designed to cope with unsigned integers instead of normal integers

	To do this we add checks for overflows: (x > 2^31 ? x - 2 ^ 32 : x)
	These are written in long form because no constant folding.
]]

local floor = math.floor

local lshift, rshift

rshift = function(a,disp)
	return floor(a % 4294967296 / 2^disp)
end

lshift = function(a,disp)
	return (a * 2^disp) % 4294967296
end

return {
	-- bit operations
	bnot = bit.bnot,
	band = bit.band,
	bor  = bit.bor,
	bxor = bit.bxor,
	rshift = rshift,
	lshift = lshift,
}
end)
local gf=_W(function(_ENV, ...)
-- finite field with base 2 and modulo irreducible polynom x^8+x^4+x^3+x+1 = 0x11d
local bxor = bit.bxor
local lshift = bit.lshift

-- private data of gf
local n = 0x100
local ord = 0xff
local irrPolynom = 0x11b
local exp = {}
local log = {}

--
-- add two polynoms (its simply xor)
--
local function add(operand1, operand2)
	return bxor(operand1,operand2)
end

--
-- subtract two polynoms (same as addition)
--
local function sub(operand1, operand2)
	return bxor(operand1,operand2)
end

--
-- inverts element
-- a^(-1) = g^(order - log(a))
--
local function invert(operand)
	-- special case for 1
	if (operand == 1) then
		return 1
	end
	-- normal invert
	local exponent = ord - log[operand]
	return exp[exponent]
end

--
-- multiply two elements using a logarithm table
-- a*b = g^(log(a)+log(b))
--
local function mul(operand1, operand2)
	if (operand1 == 0 or operand2 == 0) then
		return 0
	end

	local exponent = log[operand1] + log[operand2]
	if (exponent >= ord) then
		exponent = exponent - ord
	end
	return  exp[exponent]
end

--
-- divide two elements
-- a/b = g^(log(a)-log(b))
--
local function div(operand1, operand2)
	if (operand1 == 0)  then
		return 0
	end
	-- TODO: exception if operand2 == 0
	local exponent = log[operand1] - log[operand2]
	if (exponent < 0) then
		exponent = exponent + ord
	end
	return exp[exponent]
end

--
-- print logarithmic table
--
local function printLog()
	for i = 1, n do
		print("log(", i-1, ")=", log[i-1])
	end
end

--
-- print exponentiation table
--
local function printExp()
	for i = 1, n do
		print("exp(", i-1, ")=", exp[i-1])
	end
end

--
-- calculate logarithmic and exponentiation table
--
local function initMulTable()
	local a = 1

	for i = 0,ord-1 do
		exp[i] = a
		log[a] = i

		-- multiply with generator x+1 -> left shift + 1
		a = bxor(lshift(a, 1), a)

		-- if a gets larger than order, reduce modulo irreducible polynom
		if a > ord then
			a = sub(a, irrPolynom)
		end
	end
end

initMulTable()

return {
	add = add,
	sub = sub,
	invert = invert,
	mul = mul,
	div = dib,
	printLog = printLog,
	printExp = printExp,
}
end)
util=_W(function(_ENV, ...)
-- Cache some bit operators
local bxor = bit.bxor
local rshift = bit.rshift
local band = bit.band
local lshift = bit.lshift

--
-- calculate the parity of one byte
--
local function byteParity(byte)
	byte = bxor(byte, rshift(byte, 4))
	byte = bxor(byte, rshift(byte, 2))
	byte = bxor(byte, rshift(byte, 1))
	return band(byte, 1)
end

--
-- get byte at position index
--
local function getByte(number, index)
	if (index == 0) then
		return band(number,0xff)
	else
		return band(rshift(number, index*8),0xff)
	end
end


--
-- put number into int at position index
--
local function putByte(number, index)
	if (index == 0) then
		return band(number,0xff)
	else
		return lshift(band(number,0xff),index*8)
	end
end

--
-- convert byte array to int array
--
local function bytesToInts(bytes, start, n)
	local ints = {}
	for i = 0, n - 1 do
		ints[i + 1] =
				putByte(bytes[start + (i*4)], 3) +
				putByte(bytes[start + (i*4) + 1], 2) +
				putByte(bytes[start + (i*4) + 2], 1) +
				putByte(bytes[start + (i*4) + 3], 0)
	end
	return ints
end

--
-- convert int array to byte array
--
local function intsToBytes(ints, output, outputOffset, n)
	n = n or #ints
	for i = 0, n - 1 do
		for j = 0,3 do
			output[outputOffset + i*4 + (3 - j)] = getByte(ints[i + 1], j)
		end
	end
	return output
end

--
-- convert bytes to hexString
--
local function bytesToHex(bytes)
	local hexBytes = ""

	for i,byte in ipairs(bytes) do
		hexBytes = hexBytes .. string.format("%02x ", byte)
	end

	return hexBytes
end

local function hexToBytes(bytes)
	local out = {}
	for i = 1, #bytes, 2 do
		out[#out + 1] = tonumber(bytes:sub(i, i + 1), 16)
	end

	return out
end

--
-- convert data to hex string
--
local function toHexString(data)
	local type = type(data)
	if (type == "number") then
		return string.format("%08x",data)
	elseif (type == "table") then
		return bytesToHex(data)
	elseif (type == "string") then
		local bytes = {string.byte(data, 1, #data)}

		return bytesToHex(bytes)
	else
		return data
	end
end

local function padByteString(data)
	local dataLength = #data

	local random1 = math.random(0,255)
	local random2 = math.random(0,255)

	local prefix = string.char(random1,
		random2,
		random1,
		random2,
		getByte(dataLength, 3),
		getByte(dataLength, 2),
		getByte(dataLength, 1),
		getByte(dataLength, 0)
	)

	data = prefix .. data

	local paddingLength = math.ceil(#data/16)*16 - #data
	local padding = ""
	for i=1,paddingLength do
		padding = padding .. string.char(math.random(0,255))
	end

	return data .. padding
end

local function properlyDecrypted(data)
	local random = {string.byte(data,1,4)}

	if (random[1] == random[3] and random[2] == random[4]) then
		return true
	end

	return false
end

local function unpadByteString(data)
	if (not properlyDecrypted(data)) then
		return nil
	end

	local dataLength = putByte(string.byte(data,5), 3)
					 + putByte(string.byte(data,6), 2)
					 + putByte(string.byte(data,7), 1)
					 + putByte(string.byte(data,8), 0)

	return string.sub(data,9,8+dataLength)
end

local function xorIV(data, iv)
	for i = 1,16 do
		data[i] = bxor(data[i], iv[i])
	end
end

local function increment(data)
	local i = 16
	while true do
		local value = data[i] + 1
		if value >= 256 then
			data[i] = value - 256
			i = (i - 2) % 16 + 1
		else
			data[i] = value
			break
		end
	end
end

local function getRandomData(bytes)
	local char, random, insert = string.char, math.random, table.insert
	local result = {}

	for i=1,bytes do
		insert(result, random(0,255))
		if i % 10240 == 0 then sleep() end
	end

	return result
end

local function getRandomString(bytes)
	local char, random, insert = string.char, math.random, table.insert
	local result = {}

	for i=1,bytes do
		insert(result, char(random(0,255)))
		if i % 10240 == 0 then sleep() end
	end

	return table.concat(result)
end

return {
	byteParity = byteParity,
	getByte = getByte,
	putByte = putByte,
	bytesToInts = bytesToInts,
	intsToBytes = intsToBytes,
	bytesToHex = bytesToHex,
	hexToBytes = hexToBytes,
	toHexString = toHexString,
	padByteString = padByteString,
	properlyDecrypted = properlyDecrypted,
	unpadByteString = unpadByteString,
	xorIV = xorIV,
	increment = increment,

	getRandomData = getRandomData,
	getRandomString = getRandomString,
}
end)
aes=_W(function(_ENV, ...)
-- Implementation of AES with nearly pure lua
-- AES with lua is slow, really slow :-)

local putByte = util.putByte
local getByte = util.getByte

-- some constants
local ROUNDS = 'rounds'
local KEY_TYPE = "type"
local ENCRYPTION_KEY=1
local DECRYPTION_KEY=2

-- aes SBOX
local SBox = {}
local iSBox = {}

-- aes tables
local table0 = {}
local table1 = {}
local table2 = {}
local table3 = {}

local tableInv0 = {}
local tableInv1 = {}
local tableInv2 = {}
local tableInv3 = {}

-- round constants
local rCon = {
	0x01000000,
	0x02000000,
	0x04000000,
	0x08000000,
	0x10000000,
	0x20000000,
	0x40000000,
	0x80000000,
	0x1b000000,
	0x36000000,
	0x6c000000,
	0xd8000000,
	0xab000000,
	0x4d000000,
	0x9a000000,
	0x2f000000,
}

--
-- affine transformation for calculating the S-Box of AES
--
local function affinMap(byte)
	mask = 0xf8
	result = 0
	for i = 1,8 do
		result = bit.lshift(result,1)

		parity = util.byteParity(bit.band(byte,mask))
		result = result + parity

		-- simulate roll
		lastbit = bit.band(mask, 1)
		mask = bit.band(bit.rshift(mask, 1),0xff)
		if (lastbit ~= 0) then
			mask = bit.bor(mask, 0x80)
		else
			mask = bit.band(mask, 0x7f)
		end
	end

	return bit.bxor(result, 0x63)
end

--
-- calculate S-Box and inverse S-Box of AES
-- apply affine transformation to inverse in finite field 2^8
--
local function calcSBox()
	for i = 0, 255 do
	if (i ~= 0) then
		inverse = gf.invert(i)
	else
		inverse = i
	end
		mapped = affinMap(inverse)
		SBox[i] = mapped
		iSBox[mapped] = i
	end
end

--
-- Calculate round tables
-- round tables are used to calculate shiftRow, MixColumn and SubBytes
-- with 4 table lookups and 4 xor operations.
--
local function calcRoundTables()
	for x = 0,255 do
		byte = SBox[x]
		table0[x] = putByte(gf.mul(0x03, byte), 0)
						  + putByte(             byte , 1)
						  + putByte(             byte , 2)
						  + putByte(gf.mul(0x02, byte), 3)
		table1[x] = putByte(             byte , 0)
						  + putByte(             byte , 1)
						  + putByte(gf.mul(0x02, byte), 2)
						  + putByte(gf.mul(0x03, byte), 3)
		table2[x] = putByte(             byte , 0)
						  + putByte(gf.mul(0x02, byte), 1)
						  + putByte(gf.mul(0x03, byte), 2)
						  + putByte(             byte , 3)
		table3[x] = putByte(gf.mul(0x02, byte), 0)
						  + putByte(gf.mul(0x03, byte), 1)
						  + putByte(             byte , 2)
						  + putByte(             byte , 3)
	end
end

--
-- Calculate inverse round tables
-- does the inverse of the normal roundtables for the equivalent
-- decryption algorithm.
--
local function calcInvRoundTables()
	for x = 0,255 do
		byte = iSBox[x]
		tableInv0[x] = putByte(gf.mul(0x0b, byte), 0)
							 + putByte(gf.mul(0x0d, byte), 1)
							 + putByte(gf.mul(0x09, byte), 2)
							 + putByte(gf.mul(0x0e, byte), 3)
		tableInv1[x] = putByte(gf.mul(0x0d, byte), 0)
							 + putByte(gf.mul(0x09, byte), 1)
							 + putByte(gf.mul(0x0e, byte), 2)
							 + putByte(gf.mul(0x0b, byte), 3)
		tableInv2[x] = putByte(gf.mul(0x09, byte), 0)
							 + putByte(gf.mul(0x0e, byte), 1)
							 + putByte(gf.mul(0x0b, byte), 2)
							 + putByte(gf.mul(0x0d, byte), 3)
		tableInv3[x] = putByte(gf.mul(0x0e, byte), 0)
							 + putByte(gf.mul(0x0b, byte), 1)
							 + putByte(gf.mul(0x0d, byte), 2)
							 + putByte(gf.mul(0x09, byte), 3)
	end
end


--
-- rotate word: 0xaabbccdd gets 0xbbccddaa
-- used for key schedule
--
local function rotWord(word)
	local tmp = bit.band(word,0xff000000)
	return (bit.lshift(word,8) + bit.rshift(tmp,24))
end

--
-- replace all bytes in a word with the SBox.
-- used for key schedule
--
local function subWord(word)
	return putByte(SBox[getByte(word,0)],0)
		+ putByte(SBox[getByte(word,1)],1)
		+ putByte(SBox[getByte(word,2)],2)
		+ putByte(SBox[getByte(word,3)],3)
end

--
-- generate key schedule for aes encryption
--
-- returns table with all round keys and
-- the necessary number of rounds saved in [ROUNDS]
--
local function expandEncryptionKey(key)
	local keySchedule = {}
	local keyWords = math.floor(#key / 4)


	if ((keyWords ~= 4 and keyWords ~= 6 and keyWords ~= 8) or (keyWords * 4 ~= #key)) then
		error("Invalid key size: " .. tostring(keyWords))
		return nil
	end

	keySchedule[ROUNDS] = keyWords + 6
	keySchedule[KEY_TYPE] = ENCRYPTION_KEY

	for i = 0,keyWords - 1 do
		keySchedule[i] = putByte(key[i*4+1], 3)
					   + putByte(key[i*4+2], 2)
					   + putByte(key[i*4+3], 1)
					   + putByte(key[i*4+4], 0)
	end

	for i = keyWords, (keySchedule[ROUNDS] + 1)*4 - 1 do
		local tmp = keySchedule[i-1]

		if ( i % keyWords == 0) then
			tmp = rotWord(tmp)
			tmp = subWord(tmp)

			local index = math.floor(i/keyWords)
			tmp = bit.bxor(tmp,rCon[index])
		elseif (keyWords > 6 and i % keyWords == 4) then
			tmp = subWord(tmp)
		end

		keySchedule[i] = bit.bxor(keySchedule[(i-keyWords)],tmp)
	end

	return keySchedule
end

--
-- Inverse mix column
-- used for key schedule of decryption key
--
local function invMixColumnOld(word)
	local b0 = getByte(word,3)
	local b1 = getByte(word,2)
	local b2 = getByte(word,1)
	local b3 = getByte(word,0)

	return putByte(gf.add(gf.add(gf.add(gf.mul(0x0b, b1),
											 gf.mul(0x0d, b2)),
											 gf.mul(0x09, b3)),
											 gf.mul(0x0e, b0)),3)
		 + putByte(gf.add(gf.add(gf.add(gf.mul(0x0b, b2),
											 gf.mul(0x0d, b3)),
											 gf.mul(0x09, b0)),
											 gf.mul(0x0e, b1)),2)
		 + putByte(gf.add(gf.add(gf.add(gf.mul(0x0b, b3),
											 gf.mul(0x0d, b0)),
											 gf.mul(0x09, b1)),
											 gf.mul(0x0e, b2)),1)
		 + putByte(gf.add(gf.add(gf.add(gf.mul(0x0b, b0),
											 gf.mul(0x0d, b1)),
											 gf.mul(0x09, b2)),
											 gf.mul(0x0e, b3)),0)
end

--
-- Optimized inverse mix column
-- look at http://fp.gladman.plus.com/cryptography_technology/rijndael/aes.spec.311.pdf
-- TODO: make it work
--
local function invMixColumn(word)
	local b0 = getByte(word,3)
	local b1 = getByte(word,2)
	local b2 = getByte(word,1)
	local b3 = getByte(word,0)

	local t = bit.bxor(b3,b2)
	local u = bit.bxor(b1,b0)
	local v = bit.bxor(t,u)
	v = bit.bxor(v,gf.mul(0x08,v))
	w = bit.bxor(v,gf.mul(0x04, bit.bxor(b2,b0)))
	v = bit.bxor(v,gf.mul(0x04, bit.bxor(b3,b1)))

	return putByte( bit.bxor(bit.bxor(b3,v), gf.mul(0x02, bit.bxor(b0,b3))), 0)
		 + putByte( bit.bxor(bit.bxor(b2,w), gf.mul(0x02, t              )), 1)
		 + putByte( bit.bxor(bit.bxor(b1,v), gf.mul(0x02, bit.bxor(b0,b3))), 2)
		 + putByte( bit.bxor(bit.bxor(b0,w), gf.mul(0x02, u              )), 3)
end

--
-- generate key schedule for aes decryption
--
-- uses key schedule for aes encryption and transforms each
-- key by inverse mix column.
--
local function expandDecryptionKey(key)
	local keySchedule = expandEncryptionKey(key)
	if (keySchedule == nil) then
		return nil
	end

	keySchedule[KEY_TYPE] = DECRYPTION_KEY

	for i = 4, (keySchedule[ROUNDS] + 1)*4 - 5 do
		keySchedule[i] = invMixColumnOld(keySchedule[i])
	end

	return keySchedule
end

--
-- xor round key to state
--
local function addRoundKey(state, key, round)
	for i = 0, 3 do
		state[i + 1] = bit.bxor(state[i + 1], key[round*4+i])
	end
end

--
-- do encryption round (ShiftRow, SubBytes, MixColumn together)
--
local function doRound(origState, dstState)
	dstState[1] =  bit.bxor(bit.bxor(bit.bxor(
				table0[getByte(origState[1],3)],
				table1[getByte(origState[2],2)]),
				table2[getByte(origState[3],1)]),
				table3[getByte(origState[4],0)])

	dstState[2] =  bit.bxor(bit.bxor(bit.bxor(
				table0[getByte(origState[2],3)],
				table1[getByte(origState[3],2)]),
				table2[getByte(origState[4],1)]),
				table3[getByte(origState[1],0)])

	dstState[3] =  bit.bxor(bit.bxor(bit.bxor(
				table0[getByte(origState[3],3)],
				table1[getByte(origState[4],2)]),
				table2[getByte(origState[1],1)]),
				table3[getByte(origState[2],0)])

	dstState[4] =  bit.bxor(bit.bxor(bit.bxor(
				table0[getByte(origState[4],3)],
				table1[getByte(origState[1],2)]),
				table2[getByte(origState[2],1)]),
				table3[getByte(origState[3],0)])
end

--
-- do last encryption round (ShiftRow and SubBytes)
--
local function doLastRound(origState, dstState)
	dstState[1] = putByte(SBox[getByte(origState[1],3)], 3)
				+ putByte(SBox[getByte(origState[2],2)], 2)
				+ putByte(SBox[getByte(origState[3],1)], 1)
				+ putByte(SBox[getByte(origState[4],0)], 0)

	dstState[2] = putByte(SBox[getByte(origState[2],3)], 3)
				+ putByte(SBox[getByte(origState[3],2)], 2)
				+ putByte(SBox[getByte(origState[4],1)], 1)
				+ putByte(SBox[getByte(origState[1],0)], 0)

	dstState[3] = putByte(SBox[getByte(origState[3],3)], 3)
				+ putByte(SBox[getByte(origState[4],2)], 2)
				+ putByte(SBox[getByte(origState[1],1)], 1)
				+ putByte(SBox[getByte(origState[2],0)], 0)

	dstState[4] = putByte(SBox[getByte(origState[4],3)], 3)
				+ putByte(SBox[getByte(origState[1],2)], 2)
				+ putByte(SBox[getByte(origState[2],1)], 1)
				+ putByte(SBox[getByte(origState[3],0)], 0)
end

--
-- do decryption round
--
local function doInvRound(origState, dstState)
	dstState[1] =  bit.bxor(bit.bxor(bit.bxor(
				tableInv0[getByte(origState[1],3)],
				tableInv1[getByte(origState[4],2)]),
				tableInv2[getByte(origState[3],1)]),
				tableInv3[getByte(origState[2],0)])

	dstState[2] =  bit.bxor(bit.bxor(bit.bxor(
				tableInv0[getByte(origState[2],3)],
				tableInv1[getByte(origState[1],2)]),
				tableInv2[getByte(origState[4],1)]),
				tableInv3[getByte(origState[3],0)])

	dstState[3] =  bit.bxor(bit.bxor(bit.bxor(
				tableInv0[getByte(origState[3],3)],
				tableInv1[getByte(origState[2],2)]),
				tableInv2[getByte(origState[1],1)]),
				tableInv3[getByte(origState[4],0)])

	dstState[4] =  bit.bxor(bit.bxor(bit.bxor(
				tableInv0[getByte(origState[4],3)],
				tableInv1[getByte(origState[3],2)]),
				tableInv2[getByte(origState[2],1)]),
				tableInv3[getByte(origState[1],0)])
end

--
-- do last decryption round
--
local function doInvLastRound(origState, dstState)
	dstState[1] = putByte(iSBox[getByte(origState[1],3)], 3)
				+ putByte(iSBox[getByte(origState[4],2)], 2)
				+ putByte(iSBox[getByte(origState[3],1)], 1)
				+ putByte(iSBox[getByte(origState[2],0)], 0)

	dstState[2] = putByte(iSBox[getByte(origState[2],3)], 3)
				+ putByte(iSBox[getByte(origState[1],2)], 2)
				+ putByte(iSBox[getByte(origState[4],1)], 1)
				+ putByte(iSBox[getByte(origState[3],0)], 0)

	dstState[3] = putByte(iSBox[getByte(origState[3],3)], 3)
				+ putByte(iSBox[getByte(origState[2],2)], 2)
				+ putByte(iSBox[getByte(origState[1],1)], 1)
				+ putByte(iSBox[getByte(origState[4],0)], 0)

	dstState[4] = putByte(iSBox[getByte(origState[4],3)], 3)
				+ putByte(iSBox[getByte(origState[3],2)], 2)
				+ putByte(iSBox[getByte(origState[2],1)], 1)
				+ putByte(iSBox[getByte(origState[1],0)], 0)
end

--
-- encrypts 16 Bytes
-- key           encryption key schedule
-- input         array with input data
-- inputOffset   start index for input
-- output        array for encrypted data
-- outputOffset  start index for output
--
local function encrypt(key, input, inputOffset, output, outputOffset)
	--default parameters
	inputOffset = inputOffset or 1
	output = output or {}
	outputOffset = outputOffset or 1

	local state = {}
	local tmpState = {}

	if (key[KEY_TYPE] ~= ENCRYPTION_KEY) then
		error("No encryption key: " .. tostring(key[KEY_TYPE]) .. ", expected " .. ENCRYPTION_KEY)
		return
	end

	state = util.bytesToInts(input, inputOffset, 4)
	addRoundKey(state, key, 0)


	local round = 1
	while (round < key[ROUNDS] - 1) do
		-- do a double round to save temporary assignments
		doRound(state, tmpState)
		addRoundKey(tmpState, key, round)
		round = round + 1

		doRound(tmpState, state)
		addRoundKey(state, key, round)
		round = round + 1
	end

	doRound(state, tmpState)
	addRoundKey(tmpState, key, round)
	round = round +1

	doLastRound(tmpState, state)
	addRoundKey(state, key, round)

	return util.intsToBytes(state, output, outputOffset)
end

--
-- decrypt 16 bytes
-- key           decryption key schedule
-- input         array with input data
-- inputOffset   start index for input
-- output        array for decrypted data
-- outputOffset  start index for output
---
local function decrypt(key, input, inputOffset, output, outputOffset)
	-- default arguments
	inputOffset = inputOffset or 1
	output = output or {}
	outputOffset = outputOffset or 1

	local state = {}
	local tmpState = {}

	if (key[KEY_TYPE] ~= DECRYPTION_KEY) then
		error("No decryption key: " .. tostring(key[KEY_TYPE]))
		return
	end

	state = util.bytesToInts(input, inputOffset, 4)
	addRoundKey(state, key, key[ROUNDS])

	local round = key[ROUNDS] - 1
	while (round > 2) do
		-- do a double round to save temporary assignments
		doInvRound(state, tmpState)
		addRoundKey(tmpState, key, round)
		round = round - 1

		doInvRound(tmpState, state)
		addRoundKey(state, key, round)
		round = round - 1
	end


	doInvRound(state, tmpState)
	addRoundKey(tmpState, key, round)
	round = round - 1

	doInvLastRound(tmpState, state)
	addRoundKey(state, key, round)

	return util.intsToBytes(state, output, outputOffset)
end

-- calculate all tables when loading this file
calcSBox()
calcRoundTables()
calcInvRoundTables()

return {
	ROUNDS = ROUNDS,
	KEY_TYPE = KEY_TYPE,
	ENCRYPTION_KEY = ENCRYPTION_KEY,
	DECRYPTION_KEY = DECRYPTION_KEY,

	expandEncryptionKey = expandEncryptionKey,
	expandDecryptionKey = expandDecryptionKey,
	encrypt = encrypt,
	decrypt = decrypt,
}
end)
local buffer=_W(function(_ENV, ...)
local function new ()
	return {}
end

local function addString (stack, s)
	table.insert(stack, s)
end

local function toString (stack)
	return table.concat(stack)
end

return {
	new = new,
	addString = addString,
	toString = toString,
}
end)
ciphermode=_W(function(_ENV, ...)
local public = {}

--
-- Encrypt strings
-- key - byte array with key
-- string - string to encrypt
-- modefunction - function for cipher mode to use
--

local random = math.random
function public.encryptString(key, data, modeFunction, iv)
	if iv then
		local ivCopy = {}
		for i = 1, 16 do ivCopy[i] = iv[i] end
		iv = ivCopy
	else
		iv = {0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0}
	end

	local keySched = aes.expandEncryptionKey(key)
	local encryptedData = buffer.new()

	for i = 1, #data/16 do
		local offset = (i-1)*16 + 1
		local byteData = {string.byte(data,offset,offset +15)}

		iv = modeFunction(keySched, byteData, iv)

		buffer.addString(encryptedData, string.char(unpack(byteData)))
	end

	return buffer.toString(encryptedData)
end

--
-- the following 4 functions can be used as
-- modefunction for encryptString
--

-- Electronic code book mode encrypt function
function public.encryptECB(keySched, byteData, iv)
	aes.encrypt(keySched, byteData, 1, byteData, 1)
end

-- Cipher block chaining mode encrypt function
function public.encryptCBC(keySched, byteData, iv)
	util.xorIV(byteData, iv)
	aes.encrypt(keySched, byteData, 1, byteData, 1)
	return byteData
end

-- Output feedback mode encrypt function
function public.encryptOFB(keySched, byteData, iv)
	aes.encrypt(keySched, iv, 1, iv, 1)
	util.xorIV(byteData, iv)
	return iv
end

-- Cipher feedback mode encrypt function
function public.encryptCFB(keySched, byteData, iv)
	aes.encrypt(keySched, iv, 1, iv, 1)
	util.xorIV(byteData, iv)
	return byteData
end

function public.encryptCTR(keySched, byteData, iv)
	local nextIV = {}
	for j = 1, 16 do nextIV[j] = iv[j] end

	aes.encrypt(keySched, iv, 1, iv, 1)
	util.xorIV(byteData, iv)

	util.increment(nextIV)

	return nextIV
end

--
-- Decrypt strings
-- key - byte array with key
-- string - string to decrypt
-- modefunction - function for cipher mode to use
--
function public.decryptString(key, data, modeFunction, iv)
	if iv then
		local ivCopy = {}
		for i = 1, 16 do ivCopy[i] = iv[i] end
		iv = ivCopy
	else
		iv = {0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0}
	end

	local keySched
	if modeFunction == public.decryptOFB or modeFunction == public.decryptCFB or modeFunction == public.decryptCTR then
		keySched = aes.expandEncryptionKey(key)
	else
		keySched = aes.expandDecryptionKey(key)
	end

	local decryptedData = buffer.new()

	for i = 1, #data/16 do
		local offset = (i-1)*16 + 1
		local byteData = {string.byte(data,offset,offset +15)}

		iv = modeFunction(keySched, byteData, iv)

		buffer.addString(decryptedData, string.char(unpack(byteData)))
	end

	return buffer.toString(decryptedData)
end

--
-- the following 4 functions can be used as
-- modefunction for decryptString
--

-- Electronic code book mode decrypt function
function public.decryptECB(keySched, byteData, iv)
	aes.decrypt(keySched, byteData, 1, byteData, 1)
	return iv
end

-- Cipher block chaining mode decrypt function
function public.decryptCBC(keySched, byteData, iv)
	local nextIV = {}
	for j = 1, 16 do nextIV[j] = byteData[j] end

	aes.decrypt(keySched, byteData, 1, byteData, 1)
	util.xorIV(byteData, iv)

	return nextIV
end

-- Output feedback mode decrypt function
function public.decryptOFB(keySched, byteData, iv)
	aes.encrypt(keySched, iv, 1, iv, 1)
	util.xorIV(byteData, iv)

	return iv
end

-- Cipher feedback mode decrypt function
function public.decryptCFB(keySched, byteData, iv)
	local nextIV = {}
	for j = 1, 16 do nextIV[j] = byteData[j] end

	aes.encrypt(keySched, iv, 1, iv, 1)
	util.xorIV(byteData, iv)

	return nextIV
end

public.decryptCTR = public.encryptCTR

return public
end)
-- Simple API for encrypting strings.
--
AES128 = 16
AES192 = 24
AES256 = 32

ECBMODE = 1
CBCMODE = 2
OFBMODE = 3
CFBMODE = 4
CTRMODE = 4

local function pwToKey(password, keyLength, iv)
	local padLength = keyLength
	if (keyLength == AES192) then
		padLength = 32
	end

	if (padLength > #password) then
		local postfix = ""
		for i = 1,padLength - #password do
			postfix = postfix .. string.char(0)
		end
		password = password .. postfix
	else
		password = string.sub(password, 1, padLength)
	end

	local pwBytes = {string.byte(password,1,#password)}
	password = ciphermode.encryptString(pwBytes, password, ciphermode.encryptCBC, iv)

	password = string.sub(password, 1, keyLength)

	return {string.byte(password,1,#password)}
end

--
-- Encrypts string data with password password.
-- password  - the encryption key is generated from this string
-- data      - string to encrypt (must not be too large)
-- keyLength - length of aes key: 128(default), 192 or 256 Bit
-- mode      - mode of encryption: ecb, cbc(default), ofb, cfb
--
-- mode and keyLength must be the same for encryption and decryption.
--
function encrypt(password, data, keyLength, mode, iv)
	assert(password ~= nil, "Empty password.")
	assert(password ~= nil, "Empty data.")

	local mode = mode or CBCMODE
	local keyLength = keyLength or AES128

	local key = pwToKey(password, keyLength, iv)

	local paddedData = util.padByteString(data)

	if mode == ECBMODE then
		return ciphermode.encryptString(key, paddedData, ciphermode.encryptECB, iv)
	elseif mode == CBCMODE then
		return ciphermode.encryptString(key, paddedData, ciphermode.encryptCBC, iv)
	elseif mode == OFBMODE then
		return ciphermode.encryptString(key, paddedData, ciphermode.encryptOFB, iv)
	elseif mode == CFBMODE then
		return ciphermode.encryptString(key, paddedData, ciphermode.encryptCFB, iv)
	elseif mode == CTRMODE then
		return ciphermode.encryptString(key, paddedData, ciphermode.encryptCTR, iv)
	else
		error("Unknown mode", 2)
	end
end




--
-- Decrypts string data with password password.
-- password  - the decryption key is generated from this string
-- data      - string to encrypt
-- keyLength - length of aes key: 128(default), 192 or 256 Bit
-- mode      - mode of decryption: ecb, cbc(default), ofb, cfb
--
-- mode and keyLength must be the same for encryption and decryption.
--
function decrypt(password, data, keyLength, mode, iv)
	local mode = mode or CBCMODE
	local keyLength = keyLength or AES128

	local key = pwToKey(password, keyLength, iv)

	local plain
	if mode == ECBMODE then
		plain = ciphermode.decryptString(key, data, ciphermode.decryptECB, iv)
	elseif mode == CBCMODE then
		plain = ciphermode.decryptString(key, data, ciphermode.decryptCBC, iv)
	elseif mode == OFBMODE then
		plain = ciphermode.decryptString(key, data, ciphermode.decryptOFB, iv)
	elseif mode == CFBMODE then
		plain = ciphermode.decryptString(key, data, ciphermode.decryptCFB, iv)
	elseif mode == CTRMODE then
		plain = ciphermode.decryptString(key, data, ciphermode.decryptCTR, iv)
	else
		error("Unknown mode", 2)
	end

	result = util.unpadByteString(plain)

	if (result == nil) then
		return nil
	end

	return result
end
