mce: sign/verify fixes + test

include/codecrypt.h

@@ -191,6 +191,12 @@ public:
 	uint plain_size() {
 		return Sinv.width();
 	}
+	uint hash_size() {
+		return cipher_size();
+	}
+	uint signature_size() {
+		return plain_size();
+	}
 };
 
 class pubkey
@@ -208,6 +214,12 @@ public:
 	uint plain_size() {
 		return G.height();
 	}
+	uint hash_size() {
+		return cipher_size();
+	}
+	uint signature_size() {
+		return plain_size();
+	}
 };
 
 int generate (pubkey&, privkey&, prng&, uint m, uint t);

lib/mce.cpp

@@ -95,7 +95,7 @@ int privkey::decrypt (const bvector&in, bvector&out)
 	hperm.permute (canonical, not_permuted);
 
 	//get rid of redundancy bits
-	not_permuted.resize (Sinv.size() );
+	not_permuted.resize (plain_size() );
 
 	//unscramble the result
 	Sinv.mult_vecT_left (not_permuted, out);
@@ -117,7 +117,7 @@ int privkey::sign (const bvector&in, bvector&out, uint delta, uint attempts, prn
 	std::vector<uint> epos;
 	permutation hpermInv;
 
-	s = cipher_size();
+	s = hash_size();
 
 	if (in.size() != s) return 2;
 
@@ -128,12 +128,12 @@ int privkey::sign (const bvector&in, bvector&out, uint delta, uint attempts, prn
 
 	//prepare extra error vector
 	e.resize (s, 0);
-	epos.resize (delta);
+	epos.resize (delta, 0);
 
 	h.mult_vec_right (p, synd);
 
 	for (t = 0; t < attempts; ++t) {
-		for (i = 0; i < s; ++i) {
+		for (i = 0; i < delta; ++i) {
 			epos[i] = rng.random (s);
 			/* we don't care about (unlikely) error bit collisions
 			   (they actually don't harm anything) */
@@ -147,14 +147,15 @@ int privkey::sign (const bvector&in, bvector&out, uint delta, uint attempts, prn
 		if (syndrome_decode (synd2, fld, g, sqInv, e2) ) {
 			//decoding success!
 			p.add (e); //add original errors
-			hperm.permute (p, e2); //back to systematic (e2~=tmp)
+			hperm.permute (p, e2); //back to systematic (e2 is tmp)
+			e2.resize (signature_size() ); //strip redundancy
 			Sinv.mult_vecT_left (e2, out); //get a signature
 			return 0; //OK lol
 		}
 
 		//if this round failed, we try a new error pattern.
 
-		for (i = 0; i < s; ++i) //clear the errors for the next cycle
+		for (i = 0; i < delta; ++i) //clear the errors for the next cycle
 			e[epos[i]] = 0;
 	}
 	return 1; //couldn't decode

src/main.cpp

@@ -60,6 +60,22 @@ int main()
 
 	cout << "DECRYPTED" << endl;
 	cout << result;
+
+	/* signature test */
+
+	ccr::bvector hash, signature;
+
+	hash.resize (priv.hash_size(), 0);
+	hash[0] = 1;
+	hash[1] = 1;
+	hash[2] = 1;
+
+	cout << "SIGNING" << endl << hash;
+	priv.sign (hash, signature, 2, priv.hash_size() *priv.hash_size(), r);
+	cout << "SIGNATURE" << endl << signature;
+	if (pub.verify (signature, hash, 2) )
+		cout << "VERIFY FAIL" << endl;
+	else	cout << "VERIFY OK" << endl;
 	return 0;
 }