From b715459593f6294f233f9b127c4673d1ffd188c5 Mon Sep 17 00:00:00 2001
From: Mirek Kratochvil <exa.exa@gmail.com>
Date: Thu, 5 Apr 2012 16:25:43 +0200
Subject: [PATCH] mce encryption

---
 lib/mce.cpp  | 19 ++++++++++++++++++-
 src/main.cpp | 32 +++++++++++++++++++++++++++++++-
 2 files changed, 49 insertions(+), 2 deletions(-)

diff --git a/lib/mce.cpp b/lib/mce.cpp
index a78cd08..be3aaa8 100644
--- a/lib/mce.cpp
+++ b/lib/mce.cpp
@@ -46,8 +46,25 @@ int ccr::mce::generate (pubkey&pub, privkey&priv, prng&rng, uint m, uint t)
 
 int pubkey::encrypt (const bvector& in, bvector&out, prng&rng)
 {
+	uint s = cipher_size();
+	if (t > s) return 1;
+	if (in.size() != plain_size() ) return 2;
 
-	return -1; //TODO
+	//make a codeword
+	G.mult_vecT_left (in, out);
+
+	//add error vector
+	bvector e;
+	e.resize (s, 0);
+	for (uint n = t; n > 0;) {
+		uint p = rng.random (s);
+		if (!e[p]) {
+			e[p] = 1;
+			--n;
+		}
+	}
+	out.add (e);
+	return 0;
 }
 
 int privkey::decrypt (const bvector&in, bvector&out)
diff --git a/src/main.cpp b/src/main.cpp
index efc5400..4633094 100644
--- a/src/main.cpp
+++ b/src/main.cpp
@@ -42,6 +42,14 @@ ostream& operator<< (ostream&o, ccr::matrix m)
 	return o;
 }
 
+ostream& operator<< (ostream&o, ccr::bvector v)
+{
+	o << "vector of " << v.size() << " elements:" << endl;
+	for (uint i = 0, e = v.size(); i < e; ++i) cout << v[i];
+	cout << endl;
+	return o;
+}
+
 class primitiverng : public ccr::prng
 {
 public:
@@ -61,7 +69,7 @@ int main()
 
 	ccr::mce::privkey priv;
 	ccr::mce::pubkey pub;
-	ccr::mce::generate (pub, priv, r, 9, 15);
+	ccr::mce::generate (pub, priv, r, 9, 9);
 
 	cout << "PRIVATE KEY" << endl;
 	cout << priv.fld;
@@ -73,6 +81,28 @@ int main()
 	cout << pub.t << endl;
 	cout << pub.G;
 
+	ccr::bvector plain;
+	plain.resize (pub.plain_size() );
+	plain[0] = 1;
+	plain[1] = 1;
+	plain[2] = 1;
+
+	cout << "PLAINTEXT" << endl;
+	cout << plain;
+
+	ccr::bvector cipher;
+	pub.encrypt (plain, cipher, r);
+
+	cout << "CIPHERTEXT" << endl;
+	cout << cipher;
+
+	priv.prepare();
+
+	ccr::bvector result;
+	priv.decrypt (cipher, result);
+
+	cout << "DECRYPTED" << endl;
+	cout << result;
 	return 0;
 }