diff --git a/.gitignore b/.gitignore
index d4e2f23..3837701 100644
--- a/.gitignore
+++ b/.gitignore
@@ -19,3 +19,7 @@ latex/
 # currently masked
 src/main.c
 src/main
+
+./.settings/org.eclipse*
+
+.project
\ No newline at end of file
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
new file mode 100644
index 0000000..211a3c7
--- /dev/null
+++ b/src/ntru_decrypt.c
@@ -0,0 +1,79 @@
+/*
+ * 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
+ */
+
+#include "ntru_decrypt.h"
+
+
+/** 
+ * 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
+ * 
+ * 
+ */
+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;
+	unsigned int N = context->N;
+	unsigned int i;
+
+	pb_poly *a = build_polynom(NULL, N);
+	pb_starmultiply(priv_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(i = 0; i < N; i++){
+		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) {
+			mp_sub((&a->terms[i]),&mp_q,(&a->terms[i]));
+		}
+	}
+
+	pb_poly *d = build_polynom(NULL, N);
+
+	pb_starmultiply(a, priv_key_inv, d, context, p);
+	
+	pb_normalize(d,-1,1,context);
+
+	return d;
+}
diff --git a/src/ntru_decrypt.h b/src/ntru_decrypt.h
new file mode 100644
index 0000000..5f44005
--- /dev/null
+++ b/src/ntru_decrypt.h
@@ -0,0 +1,34 @@
+/*
+ * 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
+
+#include "poly.h"
+#include "context.h"
+
+pb_poly* ntru_decrypt(pb_poly*,
+		pb_poly*,
+		pb_poly*,
+		ntru_context*,
+		char**);
+
+#endif /* NTRU_DECRYPT */
diff --git a/src/poly.c b/src/poly.c
index e435abe..b565725 100644
--- a/src/poly.c
+++ b/src/poly.c
@@ -600,3 +600,37 @@ 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 acfb35d..bda6a85 100644
--- a/src/poly.h
+++ b/src/poly.h
@@ -214,4 +214,11 @@ bool pb_inverse_poly_p(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 */