1 files changed, 133 insertions, 0 deletions
diff --git a/src/libstrongswan/plugins/ntru/ntru_trits.c b/src/libstrongswan/plugins/ntru/ntru_trits.c
new file mode 100644
index 000000000..f82501629
--- /dev/null
+++ b/src/libstrongswan/plugins/ntru/ntru_trits.c
@@ -0,0 +1,133 @@
+/*
+ * Copyright (C) 2013 Andreas Steffen
+ * HSR Hochschule fuer Technik Rapperswil
+ *
+ * This program is free software; you can redistribute it and/or modify it
+ * under the terms of the GNU General Public License as published by the
+ * Free Software Foundation; either version 2 of the License, or (at your
+ * option) any later version.  See <http://www.fsf.org/copyleft/gpl.txt>.
+ *
+ * This program 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 General Public License
+ * for more details.
+ */
+
+#include "ntru_trits.h"
+#include "ntru_mgf1.h"
+
+#include "ntru_crypto/ntru_crypto_ntru_convert.h"
+
+#include <utils/debug.h>
+#include <utils/test.h>
+
+typedef struct private_ntru_trits_t private_ntru_trits_t;
+
+/**
+ * Private data of an ntru_trits_t object.
+ */
+struct private_ntru_trits_t {
+
+	/**
+	 * Public ntru_trits_t interface.
+	 */
+	ntru_trits_t public;
+
+	/**
+	 * Size of the trits array
+	 */
+	size_t trits_len;
+
+	/**
+	 * Array containing a trit per octet
+	 */
+	uint8_t *trits;
+
+};
+
+METHOD(ntru_trits_t, get_size, size_t,
+	private_ntru_trits_t *this)
+{
+	return this->trits_len;
+}
+
+METHOD(ntru_trits_t, get_trits, uint8_t*,
+	private_ntru_trits_t *this)
+{
+	return this->trits;
+}
+
+METHOD(ntru_trits_t, destroy, void,
+	private_ntru_trits_t *this)
+{
+	memwipe(this->trits, this->trits_len);
+	free(this->trits);
+	free(this);
+}
+
+/*
+ * Described in header.
+ */
+ntru_trits_t *ntru_trits_create(size_t len, hash_algorithm_t alg, chunk_t seed)
+{
+	private_ntru_trits_t *this;
+	uint8_t octets[HASH_SIZE_SHA512], buf[5], *trits;
+	size_t hash_len, octet_count = 0, trits_needed, i;
+	ntru_mgf1_t *mgf1;
+
+	DBG2(DBG_LIB, "MGF1 is seeded with %u bytes", seed.len);
+	mgf1 = ntru_mgf1_create(alg, seed, TRUE);
+	if (!mgf1)
+	{
+	    return NULL;
+	}
+	i = hash_len = mgf1->get_hash_size(mgf1);
+
+	INIT(this,
+		.public = {
+			.get_size = _get_size,
+			.get_trits = _get_trits,
+			.destroy = _destroy,
+		},
+		.trits_len = len,
+		.trits = malloc(len),
+	);
+
+	trits = this->trits;
+	trits_needed = this->trits_len;
+
+	while (trits_needed > 0)
+	{
+		if (i == hash_len)
+		{
+			/* get another block from MGF1 */
+			if (!mgf1->get_mask(mgf1, hash_len, octets))
+			{
+				mgf1->destroy(mgf1);
+				destroy(this);
+				return NULL;
+			}
+			octet_count += hash_len;
+			i = 0;
+		}
+		if (octets[i] < 243)  /* 243 = 3^5 */ 
+		{		
+			ntru_octet_2_trits(octets[i], (trits_needed < 5) ? buf : trits);
+			if (trits_needed < 5)
+			{
+				memcpy(trits, buf, trits_needed);
+				break;
+			}
+			trits += 5;
+			trits_needed -= 5;
+		}
+		i++;
+	}
+	DBG2(DBG_LIB, "MGF1 generates %u octets to extract %u trits",
+				   octet_count, len);
+	mgf1->destroy(mgf1);
+
+	return &this->public;
+}
+
+EXPORT_FUNCTION_FOR_TESTS(ntru, ntru_trits_create);