Implement incremental MD5

Two new functions:

md5.new(): returns a new MD5 state object with two methods:
 - MD5State:update(s) - adds the string s to the calculation
 - MD5State:finish()  - returns the final MD5 as a binary string

md5.tohex(): converts to hexadecimal the binary string returned by md5.sum() and MD5State:finish()
This commit is contained in:
Pedro Gimeno 2016-07-02 17:31:10 +02:00
parent 21d22c1868
commit 51febea6c3

59
md5.lua

@ -232,15 +232,6 @@ end
local swap = function (w) return str2bei(lei2str(w)) end
local function hex2binaryaux(hexval)
return char(tonumber(hexval, 16))
end
local function hex2binary(hex)
local result, _ = hex:gsub('..', hex2binaryaux)
return result
end
-- An MD5 mplementation in Lua, requires bitlib (hacked to use LuaBit from above, ugh)
-- 10/02/2001 jcw@equi4.com
@ -352,33 +343,53 @@ end
----------------------------------------------------------------
function md5.sumhexa(s)
local msgLen = #s
local function md5_update(self, s)
self.pos = self.pos + #s
s = self.buf .. s
for ii = 1, #s - 63, 64 do
local X = cut_le_str(sub(s,ii,ii+63),4,4,4,4,4,4,4,4,4,4,4,4,4,4,4,4)
assert(#X == 16)
X[0] = table.remove(X,1) -- zero based!
self.a,self.b,self.c,self.d = transform(self.a,self.b,self.c,self.d,X)
end
self.buf = sub(s, math.floor(#s/64)*64 + 1, #s)
end
local function md5_finish(self)
local msgLen = self.pos
local padLen = 56 - msgLen % 64
if msgLen % 64 > 56 then padLen = padLen + 64 end
if padLen == 0 then padLen = 64 end
s = s .. char(128) .. rep(char(0),padLen-1) .. lei2str(8*msgLen) .. lei2str(0)
local s = char(128) .. rep(char(0),padLen-1) .. lei2str(bit_and(8*msgLen, 0xFFFFFFFF)) .. lei2str(math.floor(msgLen/0x20000000))
md5_update(self, s)
assert(#s % 64 == 0)
assert(self.pos % 64 == 0)
return lei2str(self.a) .. lei2str(self.b) .. lei2str(self.c) .. lei2str(self.d)
end
local t = CONSTS
local a,b,c,d = t[65],t[66],t[67],t[68]
function md5.new()
return { a = CONSTS[65], b = CONSTS[66], c = CONSTS[67], d = CONSTS[68],
pos = 0,
buf = '',
update = md5_update,
finish = md5_finish }
end
for ii=1,#s,64 do
local X = cut_le_str(sub(s,ii,ii+63),4,4,4,4,4,4,4,4,4,4,4,4,4,4,4,4)
assert(#X == 16)
X[0] = table.remove(X,1) -- zero based!
a,b,c,d = transform(a,b,c,d,X)
end
return format("%08x%08x%08x%08x",swap(a),swap(b),swap(c),swap(d))
function md5.tohex(s)
return format("%08x%08x%08x%08x", str2bei(sub(s, 1, 4)), str2bei(sub(s, 5, 8)), str2bei(sub(s, 9, 12)), str2bei(sub(s, 13, 16)))
end
function md5.sum(s)
return hex2binary(md5.sumhexa(s))
local state = md5.new()
state:update(s)
return state:finish()
end
function md5.sumhexa(s)
return md5.tohex(md5.sum(s))
end
return md5