diff --git a/src/context.h b/src/context.h
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+/*
+ * Copyright (C) 2014 hasufell
+ *
+ * This file is part of a hasufell 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_CONTEXT_H
+#define NTRU_CONTEXT_H
+
+/**
+ * NTRU cryptosystem is specified by
+ * the following triple.
+ */
+typedef struct {
+	/**
+	 * maximal degree N - 1 for
+	 * all polynomials
+	 */
+	int N;
+	/**
+	 * large modulus
+	 */
+	int q;
+	/**
+	 * small modulus
+	 */
+	int p;
+} pqc_context;
+
+#endif /* NTRU_CONTEXT_H */