-- Prosody IM

-- Copyright (C) 2008-2009 Matthew Wild

-- Copyright (C) 2008-2009 Waqas Hussain

-- 

-- This project is MIT/X11 licensed. Please see the

-- COPYING file in the source package for more information.

--

local hashes = require "util.hashes"

local xor = require "bit".bxor

local t_insert, t_concat = table.insert, table.concat;

local s_char = string.char;

module "hmac"

local function arraystr(array)

	local t = {}

	for i = 1,#array do

		t_insert(t, s_char(array[i]))

	end

	return t_concat(t)

end

--[[

key

	the key to use in the hash

message

	the message to hash

hash

	the hash function

blocksize

	the blocksize for the hash function in bytes

hex

  return raw hash or hexadecimal string

--]]

function hmac(key, message, hash, blocksize, hex)

	local opad = {}

	local ipad = {}

	for i = 1,blocksize do

		opad[i] = 0x5c

		ipad[i] = 0x36

	end

	if #key > blocksize then

		key = hash(key)

	end

	for i = 1,#key do

		ipad[i] = xor(ipad[i],key:sub(i,i):byte())

		opad[i] = xor(opad[i],key:sub(i,i):byte())

	end

	opad = arraystr(opad)

	ipad = arraystr(ipad)

	if hex then

		return hash(opad..hash(ipad..message), true)

	else

		return hash(opad..hash(ipad..message))

	end

end

function md5(key, message, hex)

	return hmac(key, message, hashes.md5, 64, hex)

end

function sha1(key, message, hex)

	return hmac(key, message, hashes.sha1, 64, hex)

end

function sha256(key, message, hex)

	return hmac(key, message, hashes.sha256, 64, hex)

end

return _M