gf2m working under polys

include/codecrypt.h

@@ -104,7 +104,7 @@ public:
 
 	uint add (uint, uint);
 	uint mult (uint, uint);
-	uint exp (uint, int);
+	uint exp (uint, sint);
 	uint inv (uint);
 };
 

lib/gf2m.cpp

@@ -17,12 +17,25 @@ int gf2p_degree (uint p)
 	return r;
 }
 
+inline uint gf2p_add (uint a, uint b)
+{
+	return a ^ b;
+}
+
+void outbin (const char*n, uint x)
+{
+	cout << n << " = ";
+	for (int i = 31; i >= 0; --i) cout << (1 & (x>>i) );
+	cout << endl;
+}
+
 uint gf2p_mod (uint a, uint p)
 {
 	if (!p) return 0;
 	int t, degp = gf2p_degree (p);
-	while ( (t = gf2p_degree (a) ) >= degp)
+	while ( (t = gf2p_degree (a) ) >= degp) {
 		a ^= p << (t - degp);
+	}
 	return a;
 }
 
@@ -48,7 +61,7 @@ uint gf2p_modmult (uint a, uint b, uint p)
 		if (a & 1) r ^= b;
 		a >>= 1;
 		b <<= 1;
-		if (b <= d) b ^= p;
+		if (b >= d) b ^= p;
 	}
 	return r;
 }
@@ -81,38 +94,36 @@ bool gf2m::create (uint M)
 	return false;
 }
 
-/*
-uint gfn_mult(uint a, uint b, uint n)
+uint gf2m::add (uint a, uint b)
 {
-	uint irp=0;
-	while(n) { irp=(irp<<1)|1; n>>=1;}
-	uint r=a*b;
-	//TODO probably move this to own file
+	return gf2p_add (a, b);
 }
 
-uint gfn_inv (uint a, uint n);
+uint gf2m::mult (uint a, uint b)
+{
+	return gf2p_modmult (a, b, poly);
+}
 
-uint gfn_exp (uint a, sint k, uint n)
+uint gf2m::exp (uint a, sint k)
 {
 	if (!a) return 0;
 	if (a == 1) return 1;
 	if (k < 0) {
-		a = gfn_inv (a, n);
+		a = inv (a);
 		k = -k;
 	}
 	uint r = 1;
 	while (k) {
-		if (k & 1) r=gfn_mult(r,a,n);
-		a=gfn_mult(a,a,n);
-		k >>= 2;
+		if (k & 1) r = mult (r, a);
+		a = mult (a, a);
+		k >>= 1;
 	}
 	return r;
 }
 
-uint gfn_inv (uint a, uint n)
+uint gf2m::inv (uint a)
 {
 	if (n == 2) return a;
-	return gfn_exp (a, ( (sint) n) - 2, n);
+	return exp (a, n - 2);
 }
 
-*/

lib/polynomial.cpp

@@ -1,5 +1,4 @@
 
-#if 0
 #include "codecrypt.h"
 
 using namespace ccr;
@@ -34,7 +33,7 @@ void polynomial::add (const polynomial&f, gf2m&fld)
 {
 	int df = f.degree();
 	if (df > degree() ) resize (df + 1);
-	for (int i = 0; i <= df; ++i) item (i) = item (i) ^ f[i];
+	for (int i = 0; i <= df; ++i) item (i) = fld.add (item (i), f[i]);
 }
 
 void polynomial::mod (const polynomial&f, gf2m&fld)
@@ -42,21 +41,14 @@ void polynomial::mod (const polynomial&f, gf2m&fld)
 	int df = f.degree();
 	int d;
 	uint hi = fld.inv (f[df]);
-	cout << "mod by inv " << hi << endl;
-	dump (*this);
-	dump (f);
 	// while there's place to substract, reduce by x^(d-df)-multiply of f
 	for (d = degree(); d >= df; --d)
 		if (item (d) ) {
 			uint t = fld.mult (item (d), hi);
-			cout << "mult " << t << endl;
 			for (int i = 0; i <= df; ++i)
-				item (i + d - df) = fld.add (item (i + d - df)
-				                             , fld.mult (t, f[i]) );
-			cout << "now ";
-			dump (*this);
+				item (i + d - df) = fld.add (item (i + d - df),
+				                             fld.mult (t, f[i]) );
 		}
-	cout << "end mod" << endl;
 	strip();
 }
 
@@ -125,10 +117,8 @@ void polynomial::generate_random_irreducible (uint s, gf2m&fld, prng & rng)
 	item (s) = 1; //degree s
 	item (0) = 1 + rng.random (fld.n - 1); //not divisible by x^1
 	for (uint i = 1; i < s; ++i) item (i) = rng.random (fld.n);
-	cout << "start ";
 	dump (*this);
 	while (!is_irreducible (fld) ) {
-		cout << "retry ";
 		dump (*this);
 		uint pos = rng.random (s);
 		item (pos) = pos == 0 ?
@@ -155,4 +145,3 @@ void polynomial::compute_square_root_matrix (vector<polynomial>&r, gf2m&fld)
 
 	//TODO gauss
 }
-#endif