diff -r 000000000000 -r 598d09faf89c aeslua/gf.lua
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/aeslua/gf.lua	Wed Feb 16 20:29:33 2011 +0000
@@ -0,0 +1,117 @@
+local bit = require("bit");
+
+-- finite field with base 2 and modulo irreducible polynom x^8+x^4+x^3+x+1 = 0x11d
+local private = {};
+local public = {};
+
+local aeslua = require("aeslua");
+aeslua.gf = public;
+
+-- private data of gf
+private.n = 0x100;
+private.ord = 0xff;
+private.irrPolynom = 0x11b;
+private.exp = {};
+private.log = {};
+
+--
+-- add two polynoms (its simply xor)
+--
+function public.add(operand1, operand2) 
+	return bit.bxor(operand1,operand2);
+end
+
+-- 
+-- subtract two polynoms (same as addition)
+--
+function public.sub(operand1, operand2) 
+	return bit.bxor(operand1,operand2);
+end
+
+--
+-- inverts element
+-- a^(-1) = g^(order - log(a))
+--
+function public.invert(operand)
+	-- special case for 1 
+	if (operand == 1) then
+		return 1;
+	end;
+	-- normal invert
+	local exponent = private.ord - private.log[operand];
+	return private.exp[exponent];
+end
+
+--
+-- multiply two elements using a logarithm table
+-- a*b = g^(log(a)+log(b))
+--
+function public.mul(operand1, operand2)
+    if (operand1 == 0 or operand2 == 0) then
+        return 0;
+    end
+	
+    local exponent = private.log[operand1] + private.log[operand2];
+	if (exponent >= private.ord) then
+		exponent = exponent - private.ord;
+	end
+	return  private.exp[exponent];
+end
+
+--
+-- divide two elements
+-- a/b = g^(log(a)-log(b))
+--
+function public.div(operand1, operand2)
+    if (operand1 == 0)  then
+        return 0;
+    end
+    -- TODO: exception if operand2 == 0
+	local exponent = private.log[operand1] - private.log[operand2];
+	if (exponent < 0) then
+		exponent = exponent + private.ord;
+	end
+	return private.exp[exponent];
+end
+
+--
+-- print logarithmic table
+--
+function public.printLog()
+	for i = 1, private.n do
+		print("log(", i-1, ")=", private.log[i-1]);
+	end
+end
+
+--
+-- print exponentiation table
+--
+function public.printExp()
+	for i = 1, private.n do
+		print("exp(", i-1, ")=", private.exp[i-1]);
+	end
+end
+
+--
+-- calculate logarithmic and exponentiation table
+--
+function private.initMulTable()
+	local a = 1;
+
+	for i = 0,private.ord-1 do
+    	private.exp[i] = a;
+		private.log[a] = i;
+
+		-- multiply with generator x+1 -> left shift + 1	
+		a = bit.bxor(bit.lshift(a, 1), a);
+
+		-- if a gets larger than order, reduce modulo irreducible polynom
+		if a > private.ord then
+			a = public.sub(a, private.irrPolynom);
+		end
+	end
+end
+
+private.initMulTable();
+
+return public;