From 0fed44e2987dde1f2784635c5e5942d5405b13d8 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Christoph=20Pr=C3=BC=C3=9Fner?=
 <christoph.pruessner@fh-bielefeld.de>
Date: Tue, 8 Apr 2014 11:15:59 +0200
Subject: [PATCH 01/23] Abc

DEEFFFFFFFFFFFFFFF
---
 blah.txt | 1 +
 1 file changed, 1 insertion(+)
 create mode 100644 blah.txt

diff --git a/blah.txt b/blah.txt
new file mode 100644
index 0000000..99eb216
--- /dev/null
+++ b/blah.txt
@@ -0,0 +1 @@
+Penis
\ No newline at end of file

From 1d78b707cf6650791a4e403b7efb5747d27ccf76 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Christoph=20Pr=C3=BC=C3=9Fner?=
 <christoph.pruessner@fh-bielefeld.de>
Date: Wed, 23 Apr 2014 12:35:40 +0200
Subject: [PATCH 02/23] Deleted "blah.txt" (test-file)

---
 .project | 11 +++++++++++
 blah.txt |  1 -
 2 files changed, 11 insertions(+), 1 deletion(-)
 create mode 100644 .project
 delete mode 100644 blah.txt

diff --git a/.project b/.project
new file mode 100644
index 0000000..a2785b2
--- /dev/null
+++ b/.project
@@ -0,0 +1,11 @@
+<?xml version="1.0" encoding="UTF-8"?>
+<projectDescription>
+	<name>Semesterprojekt2014</name>
+	<comment></comment>
+	<projects>
+	</projects>
+	<buildSpec>
+	</buildSpec>
+	<natures>
+	</natures>
+</projectDescription>
diff --git a/blah.txt b/blah.txt
deleted file mode 100644
index 99eb216..0000000
--- a/blah.txt
+++ /dev/null
@@ -1 +0,0 @@
-Penis
\ No newline at end of file

From ac004e5cfe93e00a55852e9007704adf2b401183 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Christoph=20Pr=C3=BC=C3=9Fner?=
 <christoph.pruessner@fh-bielefeld.de>
Date: Wed, 23 Apr 2014 13:19:37 +0200
Subject: [PATCH 03/23] Added the following files: ntru_decrypt.(c|h)

---
 src/ntru_decrypt.c | 21 +++++++++++++++++++++
 src/ntru_decrypt.h | 27 +++++++++++++++++++++++++++
 2 files changed, 48 insertions(+)
 create mode 100644 src/ntru_decrypt.c
 create mode 100644 src/ntru_decrypt.h

diff --git a/src/ntru_decrypt.c b/src/ntru_decrypt.c
new file mode 100644
index 0000000..7797a33
--- /dev/null
+++ b/src/ntru_decrypt.c
@@ -0,0 +1,21 @@
+/*
+ * Copyright (C) 2014 FH Bielefeld
+ *
+ * This file is part of a FH Bielefeld project.
+ *
+ * This library is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU Lesser General Public
+ * License as published by the Free Software Foundation; either
+ * version 2.1 of the License, or (at your option) any later version.
+ *
+ * This library is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * Lesser General Public License for more details.
+ *
+ * You should have received a copy of the GNU Lesser General Public
+ * License along with this library; if not, write to the Free Software
+ * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston,
+ * MA  02110-1301  USA
+ */
+
diff --git a/src/ntru_decrypt.h b/src/ntru_decrypt.h
new file mode 100644
index 0000000..1170d0f
--- /dev/null
+++ b/src/ntru_decrypt.h
@@ -0,0 +1,27 @@
+/*
+ * Copyright (C) 2014 FH Bielefeld
+ *
+ * This file is part of a FH Bielefeld project.
+ *
+ * This library is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU Lesser General Public
+ * License as published by the Free Software Foundation; either
+ * version 2.1 of the License, or (at your option) any later version.
+ *
+ * This library is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * Lesser General Public License for more details.
+ *
+ * You should have received a copy of the GNU Lesser General Public
+ * License along with this library; if not, write to the Free Software
+ * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston,
+ * MA  02110-1301  USA
+ */
+
+#ifndef NTRU_DECRYPT_H
+#define NTRU_DECRYPT_H
+
+/*int ntru_decrypt(char* encr_msg, pb_poly private_key);*/
+
+#endif /* NTRU_DECRYPT */

From 00513d67018f8efcd6e78ec69d6dfcc58373c25b Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Christoph=20Pr=C3=BC=C3=9Fner?=
 <christoph.pruessner@fh-bielefeld.de>
Date: Wed, 23 Apr 2014 13:28:18 +0200
Subject: [PATCH 04/23] modified .gitignore

---
 .gitignore | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/.gitignore b/.gitignore
index d4e2f23..4905720 100644
--- a/.gitignore
+++ b/.gitignore
@@ -19,3 +19,5 @@ latex/
 # currently masked
 src/main.c
 src/main
+
+.settings/org.eclipse*
\ No newline at end of file

From 74ddfe65e72f022d7ebcc194d5eccf790b22fea8 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Christoph=20Pr=C3=BC=C3=9Fner?=
 <christoph.pruessner@fh-bielefeld.de>
Date: Wed, 23 Apr 2014 13:45:03 +0200
Subject: [PATCH 05/23] remodified gitignore and defined function
 "ntru_decrypt(..)"

---
 .gitignore         | 2 +-
 src/ntru_decrypt.h | 5 ++++-
 2 files changed, 5 insertions(+), 2 deletions(-)

diff --git a/.gitignore b/.gitignore
index 4905720..566858b 100644
--- a/.gitignore
+++ b/.gitignore
@@ -20,4 +20,4 @@ latex/
 src/main.c
 src/main
 
-.settings/org.eclipse*
\ No newline at end of file
+./.settings/org.eclipse*
\ No newline at end of file
diff --git a/src/ntru_decrypt.h b/src/ntru_decrypt.h
index 1170d0f..9da81cc 100644
--- a/src/ntru_decrypt.h
+++ b/src/ntru_decrypt.h
@@ -22,6 +22,9 @@
 #ifndef NTRU_DECRYPT_H
 #define NTRU_DECRYPT_H
 
-/*int ntru_decrypt(char* encr_msg, pb_poly private_key);*/
+#include "poly.h"
+#include "context.h"
+
+int ntru_decrypt(char *encr_msg, pb_poly *private_key, ntru_context *context, char ** decr_msg);
 
 #endif /* NTRU_DECRYPT */

From 98bdd670d844b72e04b25004e43ac9d98ba32c2a Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Christoph=20Pr=C3=BC=C3=9Fner?=
 <christoph.pruessner@fh-bielefeld.de>
Date: Wed, 23 Apr 2014 13:58:57 +0200
Subject: [PATCH 06/23] added ntru_decrypt function to ntru_decrypt.c

---
 src/ntru_decrypt.c | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/src/ntru_decrypt.c b/src/ntru_decrypt.c
index 7797a33..d385959 100644
--- a/src/ntru_decrypt.c
+++ b/src/ntru_decrypt.c
@@ -19,3 +19,6 @@
  * MA  02110-1301  USA
  */
 
+int ntru_decrypt(char *encr_msg, pb_poly *private_key, ntru_context *context, char ** decr_msg){
+	return 0;
+}

From 9cfb19ea7859944f6547569776a6685c4d7dcf75 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Christoph=20Pr=C3=BC=C3=9Fner?=
 <christoph.pruessner@fh-bielefeld.de>
Date: Fri, 2 May 2014 12:18:33 +0200
Subject: [PATCH 07/23] added commentary and implemented the pseudocode
 algorithm (ms_corourke.pdf)

---
 src/ntru_decrypt.c | 12 ++++++++++++
 1 file changed, 12 insertions(+)

diff --git a/src/ntru_decrypt.c b/src/ntru_decrypt.c
index d385959..3a46676 100644
--- a/src/ntru_decrypt.c
+++ b/src/ntru_decrypt.c
@@ -19,6 +19,18 @@
  * MA  02110-1301  USA
  */
 
+// Require: N , q, p, secret key f , inverse polynomial Fp , and encrypted message e.
 int ntru_decrypt(char *encr_msg, pb_poly *private_key, ntru_context *context, char ** decr_msg){
+	// StarMultiply(f, e, a, N, q)
+	for(int i = 0, i < N, i++){
+		if(a[i] < 0 ) {
+			a[i] = a[i] + q; // Make all coefficients positive
+		}
+		if(a[i] > q/2) {
+			a[i] = a[i] - q // Shift coefficients of a into range (−q/2, q/2)
+		}
+	}
+	// StarMultiply(a, Fp , d, N, p)
+	// {Decode returns the decrypted message, d, through the argument list.}
 	return 0;
 }

From ecdc32f5e0a55fc6ce647105d0234a97a3f6481e Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Christoph=20Pr=C3=BC=C3=9Fner?=
 <christoph.pruessner@fh-bielefeld.de>
Date: Fri, 2 May 2014 13:00:00 +0200
Subject: [PATCH 08/23] first implementation of "pseudocode algorithm"
 (ms_corourke.pdf)

---
 src/ntru_decrypt.c | 37 ++++++++++++++++++++++++++++++++++---
 src/ntru_decrypt.h |  2 ++
 2 files changed, 36 insertions(+), 3 deletions(-)

diff --git a/src/ntru_decrypt.c b/src/ntru_decrypt.c
index 3a46676..d7562a2 100644
--- a/src/ntru_decrypt.c
+++ b/src/ntru_decrypt.c
@@ -19,9 +19,27 @@
  * MA  02110-1301  USA
  */
 
+#include "ntru_decrypt.h"
+
+/*
+ * Legend
+ *
+ * N : highest degree of the polynom
+ * q : "is given" (... mod q)
+ * p : "is given" (... mod p)
+ * f : private key
+ * Fp: inverse of "modulo p"
+ * e : encrypted message
+ * a : result of first multiplication (StarMultiply(f, e, a, N, q))
+ * d : result of second multiplication (StarMultiply(a, Fp , d, N, p)), decrypted message
+ * */
+
 // Require: N , q, p, secret key f , inverse polynomial Fp , and encrypted message e.
 int ntru_decrypt(char *encr_msg, pb_poly *private_key, ntru_context *context, char ** decr_msg){
-	// StarMultiply(f, e, a, N, q)
+	// toDo q = ?, p = ?, fp = ?
+
+	pb_poly *a = first_multiply(private_key, encr_msg, q);// StarMultiply(f, e, a, N, q)
+
 	for(int i = 0, i < N, i++){
 		if(a[i] < 0 ) {
 			a[i] = a[i] + q; // Make all coefficients positive
@@ -30,7 +48,20 @@ int ntru_decrypt(char *encr_msg, pb_poly *private_key, ntru_context *context, ch
 			a[i] = a[i] - q // Shift coefficients of a into range (−q/2, q/2)
 		}
 	}
-	// StarMultiply(a, Fp , d, N, p)
+	char* d = second_multiply(a, fp, p)// StarMultiply(a, Fp , d, N, p)
+
 	// {Decode returns the decrypted message, d, through the argument list.}
-	return 0;
+	return d;
+}
+
+// toDo fix header file definition and types if needed!
+pb_poly* first_multiply(pb_poly *private_key, char *encr_msg, int q) {
+	// toDo a= f*e mod q
+	return NULL;
+}
+
+// toDo fix header file definition and types if needed!
+char* second_multiply(pb_poly *a, pb_poly *fp, int p) {
+	//toDo a*Fp mod p
+	return NULL;
 }
diff --git a/src/ntru_decrypt.h b/src/ntru_decrypt.h
index 9da81cc..92ac915 100644
--- a/src/ntru_decrypt.h
+++ b/src/ntru_decrypt.h
@@ -26,5 +26,7 @@
 #include "context.h"
 
 int ntru_decrypt(char *encr_msg, pb_poly *private_key, ntru_context *context, char ** decr_msg);
+pb_poly* first_multiply(pb_poly*, char*, int);
+char* first_multiply(pb_poly*, pb_poly*, int);
 
 #endif /* NTRU_DECRYPT */

From 4d438bb925c3cbe2fa036dc07e9d5ac3e2522c9f Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Christoph=20Pr=C3=BC=C3=9Fner?=
 <christoph.pruessner@fh-bielefeld.de>
Date: Sat, 3 May 2014 13:18:15 +0200
Subject: [PATCH 09/23] changed gitignore

---
 .gitignore | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/.gitignore b/.gitignore
index 566858b..3837701 100644
--- a/.gitignore
+++ b/.gitignore
@@ -20,4 +20,6 @@ latex/
 src/main.c
 src/main
 
-./.settings/org.eclipse*
\ No newline at end of file
+./.settings/org.eclipse*
+
+.project
\ No newline at end of file

From 06d359936a2bcf9f18b074c7dc3d3e380462c13f Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Christoph=20Pr=C3=BC=C3=9Fner?=
 <christoph.pruessner@fh-bielefeld.de>
Date: Sat, 3 May 2014 13:19:25 +0200
Subject: [PATCH 10/23] deleted .project file

---
 .project | 11 -----------
 1 file changed, 11 deletions(-)
 delete mode 100644 .project

diff --git a/.project b/.project
deleted file mode 100644
index a2785b2..0000000
--- a/.project
+++ /dev/null
@@ -1,11 +0,0 @@
-<?xml version="1.0" encoding="UTF-8"?>
-<projectDescription>
-	<name>Semesterprojekt2014</name>
-	<comment></comment>
-	<projects>
-	</projects>
-	<buildSpec>
-	</buildSpec>
-	<natures>
-	</natures>
-</projectDescription>

From b4ba4112e5a283166fb09e3ad10a295a60f5dcc3 Mon Sep 17 00:00:00 2001
From: Alexander Rolfes <arolfes@fh-bielefeld.de>
Date: Sat, 3 May 2014 13:32:59 +0200
Subject: [PATCH 11/23] Revert "first implementation of "pseudocode algorithm"
 (ms_corourke.pdf)"

This reverts commit ecdc32f5e0a55fc6ce647105d0234a97a3f6481e.
---
 src/ntru_decrypt.c | 37 +++----------------------------------
 src/ntru_decrypt.h |  2 --
 2 files changed, 3 insertions(+), 36 deletions(-)

diff --git a/src/ntru_decrypt.c b/src/ntru_decrypt.c
index d7562a2..3a46676 100644
--- a/src/ntru_decrypt.c
+++ b/src/ntru_decrypt.c
@@ -19,27 +19,9 @@
  * MA  02110-1301  USA
  */
 
-#include "ntru_decrypt.h"
-
-/*
- * Legend
- *
- * N : highest degree of the polynom
- * q : "is given" (... mod q)
- * p : "is given" (... mod p)
- * f : private key
- * Fp: inverse of "modulo p"
- * e : encrypted message
- * a : result of first multiplication (StarMultiply(f, e, a, N, q))
- * d : result of second multiplication (StarMultiply(a, Fp , d, N, p)), decrypted message
- * */
-
 // Require: N , q, p, secret key f , inverse polynomial Fp , and encrypted message e.
 int ntru_decrypt(char *encr_msg, pb_poly *private_key, ntru_context *context, char ** decr_msg){
-	// toDo q = ?, p = ?, fp = ?
-
-	pb_poly *a = first_multiply(private_key, encr_msg, q);// StarMultiply(f, e, a, N, q)
-
+	// StarMultiply(f, e, a, N, q)
 	for(int i = 0, i < N, i++){
 		if(a[i] < 0 ) {
 			a[i] = a[i] + q; // Make all coefficients positive
@@ -48,20 +30,7 @@ int ntru_decrypt(char *encr_msg, pb_poly *private_key, ntru_context *context, ch
 			a[i] = a[i] - q // Shift coefficients of a into range (−q/2, q/2)
 		}
 	}
-	char* d = second_multiply(a, fp, p)// StarMultiply(a, Fp , d, N, p)
-
+	// StarMultiply(a, Fp , d, N, p)
 	// {Decode returns the decrypted message, d, through the argument list.}
-	return d;
-}
-
-// toDo fix header file definition and types if needed!
-pb_poly* first_multiply(pb_poly *private_key, char *encr_msg, int q) {
-	// toDo a= f*e mod q
-	return NULL;
-}
-
-// toDo fix header file definition and types if needed!
-char* second_multiply(pb_poly *a, pb_poly *fp, int p) {
-	//toDo a*Fp mod p
-	return NULL;
+	return 0;
 }
diff --git a/src/ntru_decrypt.h b/src/ntru_decrypt.h
index 92ac915..9da81cc 100644
--- a/src/ntru_decrypt.h
+++ b/src/ntru_decrypt.h
@@ -26,7 +26,5 @@
 #include "context.h"
 
 int ntru_decrypt(char *encr_msg, pb_poly *private_key, ntru_context *context, char ** decr_msg);
-pb_poly* first_multiply(pb_poly*, char*, int);
-char* first_multiply(pb_poly*, pb_poly*, int);
 
 #endif /* NTRU_DECRYPT */

From 4de50e2390a2779a10ef850a2a5d3d7243af409f Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Christoph=20Pr=C3=BC=C3=9Fner?=
 <christoph.pruessner@fh-bielefeld.de>
Date: Sat, 3 May 2014 13:51:00 +0200
Subject: [PATCH 12/23] removed redundant multiplication functions

---
 src/ntru_decrypt.c | 17 +++--------------
 src/ntru_decrypt.h |  2 --
 2 files changed, 3 insertions(+), 16 deletions(-)

diff --git a/src/ntru_decrypt.c b/src/ntru_decrypt.c
index d7562a2..cfe08f4 100644
--- a/src/ntru_decrypt.c
+++ b/src/ntru_decrypt.c
@@ -20,6 +20,7 @@
  */
 
 #include "ntru_decrypt.h"
+#include "poly.h"
 
 /*
  * Legend
@@ -38,7 +39,7 @@
 int ntru_decrypt(char *encr_msg, pb_poly *private_key, ntru_context *context, char ** decr_msg){
 	// toDo q = ?, p = ?, fp = ?
 
-	pb_poly *a = first_multiply(private_key, encr_msg, q);// StarMultiply(f, e, a, N, q)
+	//toDO StarMultiply(f, e, a, N, q)
 
 	for(int i = 0, i < N, i++){
 		if(a[i] < 0 ) {
@@ -48,20 +49,8 @@ int ntru_decrypt(char *encr_msg, pb_poly *private_key, ntru_context *context, ch
 			a[i] = a[i] - q // Shift coefficients of a into range (−q/2, q/2)
 		}
 	}
-	char* d = second_multiply(a, fp, p)// StarMultiply(a, Fp , d, N, p)
+	//toDo StarMultiply(a, Fp , d, N, p)
 
 	// {Decode returns the decrypted message, d, through the argument list.}
 	return d;
 }
-
-// toDo fix header file definition and types if needed!
-pb_poly* first_multiply(pb_poly *private_key, char *encr_msg, int q) {
-	// toDo a= f*e mod q
-	return NULL;
-}
-
-// toDo fix header file definition and types if needed!
-char* second_multiply(pb_poly *a, pb_poly *fp, int p) {
-	//toDo a*Fp mod p
-	return NULL;
-}
diff --git a/src/ntru_decrypt.h b/src/ntru_decrypt.h
index 92ac915..9da81cc 100644
--- a/src/ntru_decrypt.h
+++ b/src/ntru_decrypt.h
@@ -26,7 +26,5 @@
 #include "context.h"
 
 int ntru_decrypt(char *encr_msg, pb_poly *private_key, ntru_context *context, char ** decr_msg);
-pb_poly* first_multiply(pb_poly*, char*, int);
-char* first_multiply(pb_poly*, pb_poly*, int);
 
 #endif /* NTRU_DECRYPT */

From 7349c7e8bede89ecc888dcca66b74c9928f4458f Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Christoph=20Pr=C3=BC=C3=9Fner?=
 <christoph.pruessner@fh-bielefeld.de>
Date: Sat, 3 May 2014 14:03:03 +0200
Subject: [PATCH 13/23] used pb_starmultiply for the first multiplication and
 added p, q, N

---
 src/ntru_decrypt.c | 10 ++++++++--
 src/ntru_decrypt.h |  2 +-
 2 files changed, 9 insertions(+), 3 deletions(-)

diff --git a/src/ntru_decrypt.c b/src/ntru_decrypt.c
index cfe08f4..5e048db 100644
--- a/src/ntru_decrypt.c
+++ b/src/ntru_decrypt.c
@@ -21,11 +21,12 @@
 
 #include "ntru_decrypt.h"
 #include "poly.h"
+#include "context.h"
 
 /*
  * Legend
  *
- * N : highest degree of the polynom
+ * N : maximal degree of the polynom
  * q : "is given" (... mod q)
  * p : "is given" (... mod p)
  * f : private key
@@ -36,10 +37,15 @@
  * */
 
 // Require: N , q, p, secret key f , inverse polynomial Fp , and encrypted message e.
-int ntru_decrypt(char *encr_msg, pb_poly *private_key, ntru_context *context, char ** decr_msg){
+int ntru_decrypt(pb_poly *encr_msg, pb_poly *private_key, ntru_context *context, char ** decr_msg){
 	// toDo q = ?, p = ?, fp = ?
+	unsigned int q = *context->q;
+	unsigned int p = *context->p;
+	unsigned int N = *context->N;
 
 	//toDO StarMultiply(f, e, a, N, q)
+	pb_poly *a;
+	pb_starmultiply(private_key, encr_msg, a, context, q);
 
 	for(int i = 0, i < N, i++){
 		if(a[i] < 0 ) {
diff --git a/src/ntru_decrypt.h b/src/ntru_decrypt.h
index 9da81cc..2d89c13 100644
--- a/src/ntru_decrypt.h
+++ b/src/ntru_decrypt.h
@@ -25,6 +25,6 @@
 #include "poly.h"
 #include "context.h"
 
-int ntru_decrypt(char *encr_msg, pb_poly *private_key, ntru_context *context, char ** decr_msg);
+int ntru_decrypt(pb_poly *encr_msg, pb_poly *private_key, ntru_context *context, char ** decr_msg);
 
 #endif /* NTRU_DECRYPT */

From b4a7870e9767ee65842ab18698770b19e1d14f2b Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Christoph=20Pr=C3=BC=C3=9Fner?=
 <christoph.pruessner@fh-bielefeld.de>
Date: Sat, 3 May 2014 14:07:12 +0200
Subject: [PATCH 14/23] fixed pointer arithmetical mistakes

---
 src/ntru_decrypt.c | 9 +++++----
 1 file changed, 5 insertions(+), 4 deletions(-)

diff --git a/src/ntru_decrypt.c b/src/ntru_decrypt.c
index 5e048db..9f3bae4 100644
--- a/src/ntru_decrypt.c
+++ b/src/ntru_decrypt.c
@@ -39,11 +39,12 @@
 // Require: N , q, p, secret key f , inverse polynomial Fp , and encrypted message e.
 int ntru_decrypt(pb_poly *encr_msg, pb_poly *private_key, ntru_context *context, char ** decr_msg){
 	// toDo q = ?, p = ?, fp = ?
-	unsigned int q = *context->q;
-	unsigned int p = *context->p;
-	unsigned int N = *context->N;
 
-	//toDO StarMultiply(f, e, a, N, q)
+	unsigned int q = context->q;
+	unsigned int p = context->p;
+	unsigned int N = context->N;
+
+	// StarMultiply(f, e, a, N, q)
 	pb_poly *a;
 	pb_starmultiply(private_key, encr_msg, a, context, q);
 

From fa97531eacfb14f729e3be031eb97ca233aaa5cd Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Christoph=20Pr=C3=BC=C3=9Fner?=
 <christoph.pruessner@fh-bielefeld.de>
Date: Sat, 3 May 2014 14:57:05 +0200
Subject: [PATCH 15/23] implemented the coefficient shift into a range of -q/2
 and q/2

---
 src/ntru_decrypt.c | 24 ++++++++++++++++++------
 src/ntru_decrypt.h |  5 ++++-
 2 files changed, 22 insertions(+), 7 deletions(-)

diff --git a/src/ntru_decrypt.c b/src/ntru_decrypt.c
index 9f3bae4..9815587 100644
--- a/src/ntru_decrypt.c
+++ b/src/ntru_decrypt.c
@@ -38,22 +38,34 @@
 
 // Require: N , q, p, secret key f , inverse polynomial Fp , and encrypted message e.
 int ntru_decrypt(pb_poly *encr_msg, pb_poly *private_key, ntru_context *context, char ** decr_msg){
-	// toDo q = ?, p = ?, fp = ?
+	// toDo fp = ?
 
 	unsigned int q = context->q;
 	unsigned int p = context->p;
 	unsigned int N = context->N;
 
 	// StarMultiply(f, e, a, N, q)
-	pb_poly *a;
+	pb_poly *a = build_polynom(NULL, N, context);
 	pb_starmultiply(private_key, encr_msg, a, context, q);
 
+	mp_int mp_q;
+	mp_int mp_qdiv2;
+	mp_int zero;
+
+	init_integer(&mp_q);
+	init_integer(&mp_qdiv2);
+	init_integer(&zero);
+
+	MP_SET_INT(&mp_q, q);
+	mp_div_2(&mp_q, mp_qdiv2);
+	mp_zero(&zero);
+
 	for(int i = 0, i < N, i++){
-		if(a[i] < 0 ) {
-			a[i] = a[i] + q; // Make all coefficients positive
+		if(mp_cmp(&(a->terms[i]),&zero) == MP_LT) {		// Make all coefficients positive
+			a->terms[i] = a->terms[i] + q;
 		}
-		if(a[i] > q/2) {
-			a[i] = a[i] - q // Shift coefficients of a into range (−q/2, q/2)
+		if(mp_cmp(&(a->terms[i]), &mp_qdiv2) == MP_GT) {	// Shift coefficients of a into range (−q/2, q/2)
+			a->terms[i] = a->terms[i] - mp_q;
 		}
 	}
 	//toDo StarMultiply(a, Fp , d, N, p)
diff --git a/src/ntru_decrypt.h b/src/ntru_decrypt.h
index 2d89c13..ca22f4e 100644
--- a/src/ntru_decrypt.h
+++ b/src/ntru_decrypt.h
@@ -25,6 +25,9 @@
 #include "poly.h"
 #include "context.h"
 
-int ntru_decrypt(pb_poly *encr_msg, pb_poly *private_key, ntru_context *context, char ** decr_msg);
+int ntru_decrypt(pb_poly *encr_msg,
+		pb_poly *private_key,
+		ntru_context *context,
+		char ** decr_msg);
 
 #endif /* NTRU_DECRYPT */

From 5254cf93f3d59ecf5aafe6f71d6cf7658e5ff2c8 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Christoph=20Pr=C3=BC=C3=9Fner?=
 <christoph.pruessner@fh-bielefeld.de>
Date: Sat, 3 May 2014 16:02:09 +0200
Subject: [PATCH 16/23] changed return type of ntru_decrypt, implemented second
 starmultiply, fixed numerical operations to mp_operations

---
 src/ntru_decrypt.c | 15 ++++++++++-----
 src/ntru_decrypt.h |  9 +++++----
 2 files changed, 15 insertions(+), 9 deletions(-)

diff --git a/src/ntru_decrypt.c b/src/ntru_decrypt.c
index 9815587..e50daa5 100644
--- a/src/ntru_decrypt.c
+++ b/src/ntru_decrypt.c
@@ -37,8 +37,7 @@
  * */
 
 // Require: N , q, p, secret key f , inverse polynomial Fp , and encrypted message e.
-int ntru_decrypt(pb_poly *encr_msg, pb_poly *private_key, ntru_context *context, char ** decr_msg){
-	// toDo fp = ?
+pb_poly* ntru_decrypt(pb_poly *encr_msg, pb_poly *private_key, pb_poly *Fp, ntru_context *context, char ** decr_msg){
 
 	unsigned int q = context->q;
 	unsigned int p = context->p;
@@ -62,13 +61,19 @@ int ntru_decrypt(pb_poly *encr_msg, pb_poly *private_key, ntru_context *context,
 
 	for(int i = 0, i < N, i++){
 		if(mp_cmp(&(a->terms[i]),&zero) == MP_LT) {		// Make all coefficients positive
-			a->terms[i] = a->terms[i] + q;
+			//a->terms[i] = a->terms[i] + q;
+			mp_add((&a->terms[i]),&mp_q,(&a->terms[i]));
 		}
 		if(mp_cmp(&(a->terms[i]), &mp_qdiv2) == MP_GT) {	// Shift coefficients of a into range (−q/2, q/2)
-			a->terms[i] = a->terms[i] - mp_q;
+			//a->terms[i] = a->terms[i] - mp_q;
+			mp_sub((&a->terms[i]),&mp_q,(&a->terms[i]));
 		}
 	}
-	//toDo StarMultiply(a, Fp , d, N, p)
+
+	pb_poly *d = build_polynom(NULL, N, context);
+
+	// StarMultiply(a, Fp , d, N, p)
+	pb_starmultiply(a, Fp, d, N, p);
 
 	// {Decode returns the decrypted message, d, through the argument list.}
 	return d;
diff --git a/src/ntru_decrypt.h b/src/ntru_decrypt.h
index ca22f4e..5f44005 100644
--- a/src/ntru_decrypt.h
+++ b/src/ntru_decrypt.h
@@ -25,9 +25,10 @@
 #include "poly.h"
 #include "context.h"
 
-int ntru_decrypt(pb_poly *encr_msg,
-		pb_poly *private_key,
-		ntru_context *context,
-		char ** decr_msg);
+pb_poly* ntru_decrypt(pb_poly*,
+		pb_poly*,
+		pb_poly*,
+		ntru_context*,
+		char**);
 
 #endif /* NTRU_DECRYPT */

From 4e6bb38260dd18ba3866f16a29c16ec4c1a0baa6 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Christoph=20Pr=C3=BC=C3=9Fner?=
 <christoph.pruessner@fh-bielefeld.de>
Date: Sat, 3 May 2014 17:18:23 +0200
Subject: [PATCH 17/23] numerous fixes

---
 src/Makefile       |  4 ++--
 src/ntru_decrypt.c | 12 ++++++------
 2 files changed, 8 insertions(+), 8 deletions(-)

diff --git a/src/Makefile b/src/Makefile
index 30f657e..8bea853 100644
--- a/src/Makefile
+++ b/src/Makefile
@@ -37,8 +37,8 @@ endif
 LIBS += -L.
 
 # objects
-PQC_OBJS = rand.o poly.o mem.o
-PQC_HEADERS = err.h rand.h poly.h context.h
+PQC_OBJS = rand.o poly.o mem.o ntru_decrypt.o
+PQC_HEADERS = err.h rand.h poly.h context.h ntru_decrypt.h
 # CUNIT_OBJS = cunit.o
 
 # includes
diff --git a/src/ntru_decrypt.c b/src/ntru_decrypt.c
index e50daa5..abd55df 100644
--- a/src/ntru_decrypt.c
+++ b/src/ntru_decrypt.c
@@ -20,8 +20,6 @@
  */
 
 #include "ntru_decrypt.h"
-#include "poly.h"
-#include "context.h"
 
 /*
  * Legend
@@ -42,11 +40,13 @@ pb_poly* ntru_decrypt(pb_poly *encr_msg, pb_poly *private_key, pb_poly *Fp, ntru
 	unsigned int q = context->q;
 	unsigned int p = context->p;
 	unsigned int N = context->N;
+	unsigned int i;
 
 	// StarMultiply(f, e, a, N, q)
 	pb_poly *a = build_polynom(NULL, N, context);
 	pb_starmultiply(private_key, encr_msg, a, context, q);
-
+	printf("%s\n", "Nach dem StarMultiply: ");
+	draw_polynom(a);
 	mp_int mp_q;
 	mp_int mp_qdiv2;
 	mp_int zero;
@@ -56,10 +56,10 @@ pb_poly* ntru_decrypt(pb_poly *encr_msg, pb_poly *private_key, pb_poly *Fp, ntru
 	init_integer(&zero);
 
 	MP_SET_INT(&mp_q, q);
-	mp_div_2(&mp_q, mp_qdiv2);
+	mp_div_2(&mp_q, &mp_qdiv2);
 	mp_zero(&zero);
 
-	for(int i = 0, i < N, i++){
+	for(i = 0; i < N; i++){
 		if(mp_cmp(&(a->terms[i]),&zero) == MP_LT) {		// Make all coefficients positive
 			//a->terms[i] = a->terms[i] + q;
 			mp_add((&a->terms[i]),&mp_q,(&a->terms[i]));
@@ -73,7 +73,7 @@ pb_poly* ntru_decrypt(pb_poly *encr_msg, pb_poly *private_key, pb_poly *Fp, ntru
 	pb_poly *d = build_polynom(NULL, N, context);
 
 	// StarMultiply(a, Fp , d, N, p)
-	pb_starmultiply(a, Fp, d, N, p);
+	pb_starmultiply(a, Fp, d, context, p);
 
 	// {Decode returns the decrypted message, d, through the argument list.}
 	return d;

From 74a3fa88c78458440fd1dde178228a88d4e1dd0b Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Christoph=20Pr=C3=BC=C3=9Fner?=
 <christoph.pruessner@fh-bielefeld.de>
Date: Mon, 5 May 2014 13:58:53 +0200
Subject: [PATCH 18/23] moved some lines

---
 src/ntru_decrypt.c | 6 ++++--
 1 file changed, 4 insertions(+), 2 deletions(-)

diff --git a/src/ntru_decrypt.c b/src/ntru_decrypt.c
index abd55df..5594f3e 100644
--- a/src/ntru_decrypt.c
+++ b/src/ntru_decrypt.c
@@ -45,8 +45,7 @@ pb_poly* ntru_decrypt(pb_poly *encr_msg, pb_poly *private_key, pb_poly *Fp, ntru
 	// StarMultiply(f, e, a, N, q)
 	pb_poly *a = build_polynom(NULL, N, context);
 	pb_starmultiply(private_key, encr_msg, a, context, q);
-	printf("%s\n", "Nach dem StarMultiply: ");
-	draw_polynom(a);
+
 	mp_int mp_q;
 	mp_int mp_qdiv2;
 	mp_int zero;
@@ -70,6 +69,9 @@ pb_poly* ntru_decrypt(pb_poly *encr_msg, pb_poly *private_key, pb_poly *Fp, ntru
 		}
 	}
 
+	printf("%s\np:%d", "Nach dem StarMultiply: ", p);
+	draw_polynom(a);
+
 	pb_poly *d = build_polynom(NULL, N, context);
 
 	// StarMultiply(a, Fp , d, N, p)

From dd73a662a0ef00b68bde9700a1b6b0e3095a6d1a Mon Sep 17 00:00:00 2001
From: Alexander Rolfes <arolfes@fh-bielefeld.de>
Date: Mon, 5 May 2014 21:51:58 +0200
Subject: [PATCH 19/23] DOXYGEN: Documentation of ntru_decrypt function Removed
 unnecessary comments inside of function and wrote a Doxygen compliant comment
 above the function

---
 src/ntru_decrypt.c | 43 ++++++++++++++++++-------------------------
 1 file changed, 18 insertions(+), 25 deletions(-)

diff --git a/src/ntru_decrypt.c b/src/ntru_decrypt.c
index 5594f3e..fd9d93d 100644
--- a/src/ntru_decrypt.c
+++ b/src/ntru_decrypt.c
@@ -21,28 +21,28 @@
 
 #include "ntru_decrypt.h"
 
-/*
- * Legend
- *
- * N : maximal degree of the polynom
- * q : "is given" (... mod q)
- * p : "is given" (... mod p)
- * f : private key
- * Fp: inverse of "modulo p"
- * e : encrypted message
- * a : result of first multiplication (StarMultiply(f, e, a, N, q))
- * d : result of second multiplication (StarMultiply(a, Fp , d, N, p)), decrypted message
- * */
 
-// Require: N , q, p, secret key f , inverse polynomial Fp , and encrypted message e.
-pb_poly* ntru_decrypt(pb_poly *encr_msg, pb_poly *private_key, pb_poly *Fp, ntru_context *context, char ** decr_msg){
+/** 
+ * Decryption of the given Polynom with the private key, its inverse
+ * and the fitting ntru_context
+ *
+ * @param encr_msg encrypted polynom with maximum length of N from
+ * 		the given context
+ * @param priv_key the polynom containing the private key to decrypt
+ * 		the message
+ * @param priv_key_inv the inverse polynome to the private key
+ * @param context the ntru_context 
+ * @param decr_msg may contain the decrypted polynome at some point
+ * @returns the decrypted polynome at the moment
+ * 
+ * 
+ */
 
 	unsigned int q = context->q;
 	unsigned int p = context->p;
 	unsigned int N = context->N;
 	unsigned int i;
 
-	// StarMultiply(f, e, a, N, q)
 	pb_poly *a = build_polynom(NULL, N, context);
 	pb_starmultiply(private_key, encr_msg, a, context, q);
 
@@ -59,24 +59,17 @@ pb_poly* ntru_decrypt(pb_poly *encr_msg, pb_poly *private_key, pb_poly *Fp, ntru
 	mp_zero(&zero);
 
 	for(i = 0; i < N; i++){
-		if(mp_cmp(&(a->terms[i]),&zero) == MP_LT) {		// Make all coefficients positive
-			//a->terms[i] = a->terms[i] + q;
+		if(mp_cmp(&(a->terms[i]),&zero) == MP_LT) {
 			mp_add((&a->terms[i]),&mp_q,(&a->terms[i]));
 		}
-		if(mp_cmp(&(a->terms[i]), &mp_qdiv2) == MP_GT) {	// Shift coefficients of a into range (−q/2, q/2)
-			//a->terms[i] = a->terms[i] - mp_q;
+		if(mp_cmp(&(a->terms[i]), &mp_qdiv2) == MP_GT) 
 			mp_sub((&a->terms[i]),&mp_q,(&a->terms[i]));
 		}
 	}
 
-	printf("%s\np:%d", "Nach dem StarMultiply: ", p);
-	draw_polynom(a);
-
 	pb_poly *d = build_polynom(NULL, N, context);
 
-	// StarMultiply(a, Fp , d, N, p)
 	pb_starmultiply(a, Fp, d, context, p);
-
-	// {Decode returns the decrypted message, d, through the argument list.}
+	
 	return d;
 }

From 01a08fdafad11d3a5ce19c83b398dea92e723951 Mon Sep 17 00:00:00 2001
From: Alexander Rolfes <arolfes@fh-bielefeld.de>
Date: Mon, 5 May 2014 21:53:41 +0200
Subject: [PATCH 20/23] CODE: Rename of key-Parameters Renamed private_key and
 Fp to priv_key and priv_key_inv

---
 src/ntru_decrypt.c | 6 ++++--
 1 file changed, 4 insertions(+), 2 deletions(-)

diff --git a/src/ntru_decrypt.c b/src/ntru_decrypt.c
index fd9d93d..bccb4b4 100644
--- a/src/ntru_decrypt.c
+++ b/src/ntru_decrypt.c
@@ -37,6 +37,8 @@
  * 
  * 
  */
+pb_poly* ntru_decrypt(pb_poly *encr_msg, pb_poly *priv_key, 
+	pb_poly *priv_key_inv, ntru_context *context, char ** decr_msg){
 
 	unsigned int q = context->q;
 	unsigned int p = context->p;
@@ -44,7 +46,7 @@
 	unsigned int i;
 
 	pb_poly *a = build_polynom(NULL, N, context);
-	pb_starmultiply(private_key, encr_msg, a, context, q);
+	pb_starmultiply(priv_key, encr_msg, a, context, q);
 
 	mp_int mp_q;
 	mp_int mp_qdiv2;
@@ -69,7 +71,7 @@
 
 	pb_poly *d = build_polynom(NULL, N, context);
 
-	pb_starmultiply(a, Fp, d, context, p);
+	pb_starmultiply(a, priv_key_inv, d, context, p);
 	
 	return d;
 }

From 1412ba0d1adcc9fedbc5be3a6ee6e5b213e90fc7 Mon Sep 17 00:00:00 2001
From: Alexander Rolfes <arolfes@fh-bielefeld.de>
Date: Mon, 5 May 2014 21:56:44 +0200
Subject: [PATCH 21/23] CODE: Fixed missing bracket

---
 src/ntru_decrypt.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/src/ntru_decrypt.c b/src/ntru_decrypt.c
index bccb4b4..3d3d128 100644
--- a/src/ntru_decrypt.c
+++ b/src/ntru_decrypt.c
@@ -64,7 +64,7 @@ pb_poly* ntru_decrypt(pb_poly *encr_msg, pb_poly *priv_key,
 		if(mp_cmp(&(a->terms[i]),&zero) == MP_LT) {
 			mp_add((&a->terms[i]),&mp_q,(&a->terms[i]));
 		}
-		if(mp_cmp(&(a->terms[i]), &mp_qdiv2) == MP_GT) 
+		if(mp_cmp(&(a->terms[i]), &mp_qdiv2) == MP_GT) {
 			mp_sub((&a->terms[i]),&mp_q,(&a->terms[i]));
 		}
 	}

From 40303356619338eb876546089fd68e38304774f2 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Christoph=20Pr=C3=BC=C3=9Fner?=
 <christoph.pruessner@fh-bielefeld.de>
Date: Mon, 12 May 2014 13:46:59 +0200
Subject: [PATCH 22/23] POLY: implemented pb_normalize

normalizes a polynom by defining a numerical range
for each factor of a polynom.
---
 src/poly.c | 34 ++++++++++++++++++++++++++++++++++
 src/poly.h |  7 +++++++
 2 files changed, 41 insertions(+)

diff --git a/src/poly.c b/src/poly.c
index c6f77f5..6d9c2b2 100644
--- a/src/poly.c
+++ b/src/poly.c
@@ -432,3 +432,37 @@ void draw_polynom(pb_poly * const poly)
 	}
 	printf("\n");
 }
+
+void pb_normalize(pb_poly *poly, int low_border, int high_border, ntru_context *ctx){
+	unsigned int p = ctx->p;
+	unsigned int N = ctx->N;
+
+	mp_int mp_p;
+	mp_int mp_low_border;
+	mp_int mp_high_border;
+
+	init_integer(&mp_low_border);
+	init_integer(&mp_high_border);
+	init_integer(&mp_p);
+
+	MP_SET_INT(&mp_p, p);
+	MP_SET_INT(&mp_low_border,(unsigned long)abs(low_border));
+	mp_neg(&mp_low_border,&mp_low_border);
+	MP_SET_INT(&mp_high_border,high_border);
+
+
+	unsigned int i;
+	for(i = 0; i < N; i++){
+		if(mp_cmp(&(poly->terms[i]),&mp_low_border) == MP_LT) {
+			mp_add(&(poly->terms[i]),&mp_p,&(poly->terms[i]));
+		} else if(mp_cmp(&(poly->terms[i]),&mp_high_border) == MP_GT) {
+			mp_sub(&(poly->terms[i]),&mp_p,&(poly->terms[i]));
+		}
+	}
+}
+
+void draw_mp_int(mp_int *digit) {
+	char buf[8192];
+	mp_toradix(digit, buf, 10);
+	printf("%s\n",buf);
+}
diff --git a/src/poly.h b/src/poly.h
index 77a9b54..7f961a1 100644
--- a/src/poly.h
+++ b/src/poly.h
@@ -184,4 +184,11 @@ bool pb_inverse_poly_q(pb_poly *a,
 
 void draw_polynom(pb_poly * const poly);
 
+void pb_normalize(pb_poly*,
+		int,
+		int,
+		ntru_context*);
+
+void draw_mp_int(mp_int*);
+
 #endif /* NTRU_POLY_H */

From f8f7634c840f73b25c6ef816751f18e836bf132a Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Christoph=20Pr=C3=BC=C3=9Fner?=
 <christoph.pruessner@fh-bielefeld.de>
Date: Mon, 12 May 2014 13:49:00 +0200
Subject: [PATCH 23/23] DEC

ntru_decrypt now uses pb_normalize
---
 src/ntru_decrypt.c | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/src/ntru_decrypt.c b/src/ntru_decrypt.c
index 3d3d128..5eba7a9 100644
--- a/src/ntru_decrypt.c
+++ b/src/ntru_decrypt.c
@@ -73,5 +73,7 @@ pb_poly* ntru_decrypt(pb_poly *encr_msg, pb_poly *priv_key,
 
 	pb_starmultiply(a, priv_key_inv, d, context, p);
 	
+	pb_normalize(d,-1,1,context);
+
 	return d;
 }