Created bliss_bitpacker class to encode BLISS signatures

src/libstrongswan/plugins/bliss/Makefile.am

@@ -18,6 +18,7 @@ libstrongswan_bliss_la_SOURCES = \
 	bliss_public_key.h bliss_public_key.c \
 	bliss_signature.h bliss_signature.c \
 	bliss_utils.h bliss_utils.c \
+	bliss_bitpacker.h bliss_bitpacker.c \
 	bliss_fft.h bliss_fft.c \
 	bliss_fft_params.h bliss_fft_params.c \
 	bliss_sampler.h bliss_sampler.c
@@ -30,6 +31,7 @@ check_PROGRAMS = $(TESTS)
 
 bliss_tests_SOURCES = \
 	suites/test_bliss_fft.c \
+	suites/test_bliss_bitpacker.c \
 	suites/test_bliss_sign.c \
 	bliss_fft_params.c \
 	bliss_fft.c \
@@ -39,6 +41,7 @@ bliss_tests_SOURCES = \
 	bliss_sampler.c \
 	bliss_signature.c \
 	bliss_utils.c \
+	bliss_bitpacker.c \
 	bliss_tests.h bliss_tests.c
 
 bliss_tests_CFLAGS = \

src/libstrongswan/plugins/bliss/bliss_bitpacker.c

@@ -0,0 +1,203 @@
+/*
+ * Copyright (C) 2014 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;https://www.hsr.ch/HSR-intern-Anmeldung.4409.0.html?&no_cache=1 without even the implied warranty of MERCHANTABILITY
+ * or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
+ * for more details.
+ */
+
+#include "bliss_bitpacker.h"
+
+typedef struct private_bliss_bitpacker_t private_bliss_bitpacker_t;
+
+/**
+ * Private data structure for bliss_bitpacker_t object
+ */
+struct private_bliss_bitpacker_t {
+	/**
+	 * Public interface.
+	 */
+	bliss_bitpacker_t public;
+
+	/**
+	 * Current number of bits written to buffer
+	 */
+	size_t bits;
+
+	/**
+	 * Bit buffer for up to 16 bits
+	 */
+	uint16_t bits_buf;
+
+	/**
+	 * Bits left in the bit buffer
+	 */
+	size_t bits_left;
+
+	/**
+	 * Buffer
+	 */
+	chunk_t buf;
+
+	/**
+	 * Read/Write pointer into buffer
+	 */
+	chunk_t pos;
+
+};
+
+METHOD(bliss_bitpacker_t, get_bits, size_t,
+	private_bliss_bitpacker_t *this)
+{
+	return this->bits;
+}
+
+METHOD(bliss_bitpacker_t, write_bits, bool,
+	private_bliss_bitpacker_t *this, uint16_t value, size_t bits)
+{
+	if (bits > 16)
+	{
+		return FALSE;
+	}
+	this->bits += bits;
+	value &= (1 << bits) - 1;
+
+	while (TRUE)
+	{
+		if (bits <= this->bits_left)
+		{
+			this->bits_buf |= value << (this->bits_left - bits);
+			this->bits_left -= bits;
+			return TRUE;
+		}
+
+		this->bits_buf |= value >> (bits - this->bits_left);
+		value &= (1 << (bits - this->bits_left)) - 1;
+		bits -= this->bits_left;
+
+		if (this->pos.len < 4)
+		{
+			return FALSE;
+		}
+		htoun16(this->pos.ptr, this->bits_buf);
+		this->pos = chunk_skip(this->pos, 2);
+		this->bits_buf = 0;
+		this->bits_left = 16;
+	}
+}
+
+METHOD(bliss_bitpacker_t, read_bits, bool,
+	private_bliss_bitpacker_t *this, uint16_t *value, size_t bits)
+{
+	if (bits > 16)
+	{
+		return FALSE;
+	}
+	*value = 0;
+
+	while (TRUE)
+	{
+		if (this->bits_left == 0)
+		{
+			if (this->pos.len < 2)
+			{
+				return FALSE;
+			}
+			this->bits_buf = untoh16(this->pos.ptr);
+			this->pos = chunk_skip(this->pos, 2);
+			this->bits_left = 16;
+		}
+		if (bits <= this->bits_left)
+		{
+			*value |= this->bits_buf >> (this->bits_left - bits);
+			this->bits_buf &= (1 << (this->bits_left - bits)) - 1;
+			this->bits_left -= bits;
+
+			return TRUE;
+		}
+		*value |= this->bits_buf << (bits - this->bits_left);
+		bits -= this->bits_left;
+		this->bits_left = 0;
+	}
+}
+
+METHOD(bliss_bitpacker_t, extract_buf, chunk_t,
+	private_bliss_bitpacker_t *this)
+{
+	chunk_t buf;
+
+	htoun16(this->pos.ptr, this->bits_buf);
+	this->pos.len -= 2;
+	buf = this->buf;
+	buf.len = this->buf.len - this->pos.len - this->bits_left/8;
+	this->buf = this->pos = chunk_empty;
+
+	return buf;
+}
+
+METHOD(bliss_bitpacker_t, destroy, void,
+	private_bliss_bitpacker_t *this)
+{
+	free(this->buf.ptr);
+	free(this);
+}
+
+/**
+ * See header.
+ */
+bliss_bitpacker_t *bliss_bitpacker_create(size_t max_bits)
+{
+	private_bliss_bitpacker_t *this;
+
+	INIT(this,
+		.public = {
+			.get_bits = _get_bits,
+			.write_bits = _write_bits,
+			.read_bits = _read_bits,
+			.extract_buf = _extract_buf,
+			.destroy = _destroy,
+		},
+		.bits_left = 16,
+		.buf = chunk_alloc(round_up(max_bits, 16)/8),
+	);
+
+	this->pos = this->buf;
+
+	return &this->public;
+}
+
+/**
+ * See header.
+ */
+bliss_bitpacker_t *bliss_bitpacker_create_from_data(chunk_t data)
+{
+	private_bliss_bitpacker_t *this;
+
+	INIT(this,
+		.public = {
+			.get_bits = _get_bits,
+			.write_bits = _write_bits,
+			.read_bits = _read_bits,
+			.extract_buf = _extract_buf,
+			.destroy = _destroy,
+		},
+		.bits = 8 * data.len,
+		.buf = chunk_alloc(round_up(data.len, 2)),
+	);
+
+	memcpy(this->buf.ptr, data.ptr, data.len);
+	if (this->buf.len > data.len)
+	{
+		*(this->buf.ptr + data.len) = 0x00;
+	}
+	this->pos = this->buf;
+
+	return &this->public;
+}

src/libstrongswan/plugins/bliss/bliss_bitpacker.h

@@ -0,0 +1,85 @@
+/*
+ * Copyright (C) 2014 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.
+ */
+
+/**
+ * @defgroup bliss_bitpacker bliss_bitpacker
+ * @{ @ingroup bliss_p
+ */
+
+#ifndef BLISS_BITPACKER_H_
+#define BLISS_BITPACKER_H_
+
+#include <library.h>
+
+typedef struct bliss_bitpacker_t bliss_bitpacker_t;
+
+/**
+ * Reads and writes a variable number of bits in packed format
+ * from and to an octet buffer
+ */
+struct bliss_bitpacker_t {
+
+	/**
+	 * Get the number of bits written into buffer
+	 *
+	 * @result			Number of bits written
+	 */
+	size_t (*get_bits)(bliss_bitpacker_t *this);
+
+	/**
+	 * Get the prime modulus of the Number Theoretic Transform
+	 *
+	 * @param value		Value to be written
+	 * @param bits		Number of bits to be written
+	 * @result			TRUE if value could be written into buffer
+	 */
+	bool (*write_bits)(bliss_bitpacker_t *this, uint16_t value, size_t bits);
+
+
+	/**
+	 * Get the prime modulus of the Number Theoretic Transform
+	 *
+	 * @param value		Value returned
+	 * @param bits		Number of bits to be read
+	 * @result			TRUE if value could be read from buffer
+	 */
+	bool (*read_bits)(bliss_bitpacker_t *this, uint16_t *value, size_t bits);
+
+	/**
+	 * Detach the internal octet buffer and return it
+	 */
+	chunk_t (*extract_buf)(bliss_bitpacker_t *this);
+
+	/**
+	 * Destroy bliss_bitpacker_t object
+	 */
+	void (*destroy)(bliss_bitpacker_t *this);
+};
+
+/**
+ * Create a bliss_bitpacker_t object for writing
+ *
+ * @param bits			Total number of bits to be stored 
+ */
+bliss_bitpacker_t* bliss_bitpacker_create(size_t max_bits);
+
+/**
+ * Create a bliss_bitpacker_t object for reading
+ *
+ * @param data			Packed array of bits 
+ */
+bliss_bitpacker_t* bliss_bitpacker_create_from_data(chunk_t data);
+
+#endif /** BLISS_BITPACKER_H_ @}*/

src/libstrongswan/plugins/bliss/bliss_param_set.c

@@ -136,10 +136,11 @@ static bliss_param_set_t bliss_param_sets[] = {
 		.c = c_bliss_i,
 		.c_cols = 16,
 		.c_rows = 21,
+		.z1_bits = 12,
 		.d = 10,
 		.p = 24,
 		.M = 46539,
-		.B_inf = 2100,
+		.B_inf = 2047, /* reduced from 2100 due to 12 bit z1 encoding */
 		.B_l2 = 12872 * 12872
       },
 
@@ -162,6 +163,7 @@ static bliss_param_set_t bliss_param_sets[] = {
 		.c = c_bliss_iii,
 		.c_cols = 16,
 		.c_rows = 21,
+		.z1_bits = 12,
 		.d = 9,
 		.p = 48,
 		.M = 128113,
@@ -188,6 +190,7 @@ static bliss_param_set_t bliss_param_sets[] = {
 		.c = c_bliss_iv,
 		.c_cols = 16,
 		.c_rows = 22,
+		.z1_bits = 12,
 		.d = 8,
 		.p = 96,
 		.M = 244186,

src/libstrongswan/plugins/bliss/bliss_param_set.h

@@ -131,7 +131,12 @@ struct bliss_param_set_t {
 	size_t c_rows;
 
 	/**
-	 * Number of bits to be dropped after rounding
+	 * Number of bits in z1
+	 */
+	uint16_t z1_bits;
+
+	/**
+	 * Number of z2 bits to be dropped after rounding
 	 */
 	uint16_t d;
 

src/libstrongswan/plugins/bliss/bliss_signature.c

@@ -14,6 +14,7 @@
  */
 
 #include "bliss_signature.h"
+#include "bliss_bitpacker.h"
 
 
 typedef struct private_bliss_signature_t private_bliss_signature_t;
@@ -47,44 +48,41 @@ struct private_bliss_signature_t {
 	 */
 	uint16_t *c_indices;
 
-	/**
-	 * Compressed encoding of BLISS signature
-	 */
-	chunk_t encoding;
-
 };
 
 METHOD(bliss_signature_t, get_encoding, chunk_t,
 	private_bliss_signature_t *this)
 {
-	if (this->encoding.len == 0)
+	bliss_bitpacker_t *packer;
+	uint16_t z2d_bits;
+	chunk_t encoding;
+	int i;
+
+	z2d_bits = this->set->z1_bits - this->set->d;
+
+	packer = bliss_bitpacker_create(this->set->n * this->set->z1_bits +
+									this->set->n * z2d_bits +
+									this->set->kappa * this->set->n_bits);
+
+	for (i = 0; i < this->set->n; i++)
 	{
-		uint8_t *pos;
-		int i;
-
-		this->encoding = chunk_alloc(this->set->kappa * sizeof(uint16_t) +
-									 this->set->n * sizeof(int16_t) +
-									 this->set->n * sizeof(int8_t)),
-		pos = this->encoding.ptr;
-
-		for (i = 0; i < this->set->kappa; i++)
-		{
-			htoun16(pos, this->c_indices[i]);
-			pos += 2;
-		}
-		for (i = 0; i < this->set->n; i++)
-		{
-			htoun16(pos, (uint16_t)this->z1[i]);
-			pos += 2;
-		}
-		for (i = 0; i < this->set->n; i++)
-		{
-			*pos++ = (uint8_t)this->z2d[i];
-		}
-		DBG2(DBG_LIB, "generated BLISS signature (%u bytes)", 
-					   this->encoding.len);
+		packer->write_bits(packer, this->z1[i], this->set->z1_bits);
 	}
-	return chunk_clone(this->encoding);
+	for (i = 0; i < this->set->n; i++)
+	{
+		packer->write_bits(packer, this->z2d[i], z2d_bits);
+	}
+	for (i = 0; i < this->set->kappa; i++)
+	{
+		packer->write_bits(packer, this->c_indices[i], this->set->n_bits);
+	}
+	encoding = packer->extract_buf(packer);
+
+	DBG2(DBG_LIB, "generated BLISS signature (%u bits encoded in %u bytes)",
+				   packer->get_bits(packer), encoding.len);
+	packer->destroy(packer);
+
+	return encoding;
 }
 
 METHOD(bliss_signature_t, get_parameters, void,
@@ -102,7 +100,6 @@ METHOD(bliss_signature_t, destroy, void,
 	free(this->z1);
 	free(this->z2d);
 	free(this->c_indices);
-	free(this->encoding.ptr);
 	free(this);
 }
 
@@ -135,11 +132,16 @@ bliss_signature_t *bliss_signature_create_from_data(bliss_param_set_t *set,
 													chunk_t encoding)
 {
 	private_bliss_signature_t *this;
-	uint8_t *pos;
+	bliss_bitpacker_t *packer;
+	uint32_t z1_sign, z1_mask;
+	uint16_t z2d_sign, z2d_mask, value, z1_bits, z2d_bits;
 	int i;
 
-	if (encoding.len != set->kappa * sizeof(uint16_t) +
-						set->n * sizeof(int16_t) + set->n * sizeof(int8_t))
+	z1_bits  = set->z1_bits;
+	z2d_bits = set->z1_bits - set->d;
+
+	if (8 * encoding.len < set->n * set->z1_bits + set->n * z2d_bits +
+						   set->kappa * set->n_bits)
 	{
 		DBG1(DBG_LIB, "incorrect BLISS signature size");
 		return NULL;
@@ -155,25 +157,33 @@ bliss_signature_t *bliss_signature_create_from_data(bliss_param_set_t *set,
 		.z1  = malloc(set->n * sizeof(int32_t)),
 		.z2d = malloc(set->n * sizeof(int16_t)),
 		.c_indices = malloc(set->n * sizeof(uint16_t)),
-		.encoding = chunk_clone(encoding),
 	);
 
-	pos = encoding.ptr;
+	packer = bliss_bitpacker_create_from_data(encoding);
 
+	z1_sign =   1 << (z1_bits - 1);
+	z1_mask = ((1 << (32 - z1_bits)) - 1) << z1_bits;
+
+	for (i = 0; i < set->n; i++)
+	{
+		packer->read_bits(packer, &value, z1_bits);
+		this->z1[i] = value & z1_sign ? value | z1_mask : value;
+	}
+
+	z2d_sign =   1 << (z2d_bits - 1);
+	z2d_mask = ((1 << (16 - z2d_bits)) - 1) << z2d_bits;
+
+	for (i = 0; i < set->n; i++)
+	{
+		packer->read_bits(packer, &value, z2d_bits);
+		this->z2d[i] = value & z2d_sign ? value | z2d_mask : value;
+	}
 	for (i = 0; i < set->kappa; i++)
 	{
-		this->c_indices[i] = untoh16(pos);
-		pos += 2;
-	}
-	for (i = 0; i < set->n; i++)
-	{
-		this->z1[i] = (int16_t)untoh16(pos);
-		pos += 2;
-	}
-	for (i = 0; i < set->n; i++)
-	{
-		this->z2d[i] = (int8_t)(*pos++);
+		packer->read_bits(packer, &value, set->n_bits);
+		this->c_indices[i] = value;
 	}
+	packer->destroy(packer);
 
 	return &this->public;
 }

src/libstrongswan/plugins/bliss/bliss_tests.h

@@ -14,5 +14,6 @@
  */
 
 TEST_SUITE(bliss_fft_suite_create)
+TEST_SUITE(bliss_bitpacker_suite_create)
 TEST_SUITE(bliss_sign_suite_create)
 

src/libstrongswan/plugins/bliss/suites/test_bliss_bitpacker.c

@@ -0,0 +1,108 @@
+/*
+ * Copyright (C) 2014 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 "test_suite.h"
+
+#include <bliss_bitpacker.h>
+
+static uint16_t bits[] = { 0, 1, 2, 3, 4, 7, 1, 14, 2, 29, 3, 28, 67};
+
+static chunk_t packed_bits = chunk_from_chars(0x6e, 0x71, 0xe1, 0x74,
+											  0x37, 0x21, 0x80);
+
+START_TEST(test_bliss_sign_bitpacker_write)
+{
+	chunk_t buf;
+	bliss_bitpacker_t *packer;
+	int i;
+
+	packer = bliss_bitpacker_create(49);
+
+	ck_assert(!packer->write_bits(packer, 0, 17));
+
+	for (i = 0; i < countof(bits); i++)
+	{
+		ck_assert(packer->write_bits(packer, bits[i], 1 + i/2));
+	}
+	buf = packer->extract_buf(packer);
+	ck_assert_int_eq(packer->get_bits(packer), 49);
+	ck_assert_chunk_eq(buf, packed_bits);
+
+	packer->destroy(packer);
+	free(buf.ptr);
+}
+END_TEST
+
+START_TEST(test_bliss_sign_bitpacker_read)
+{
+	uint16_t value;
+	bliss_bitpacker_t *packer;
+	int i;
+
+	packer = bliss_bitpacker_create_from_data(packed_bits);
+
+	ck_assert(!packer->read_bits(packer, &value, 17));
+
+	for (i = 0; i < countof(bits); i++)
+	{
+		ck_assert(packer->read_bits(packer, &value, 1 + i/2));
+		ck_assert_int_eq(value, bits[i]);
+	}
+	ck_assert(!packer->read_bits(packer, &value, 16));
+
+	packer->destroy(packer);
+}
+END_TEST
+
+START_TEST(test_bliss_sign_bitpacker_fail)
+{
+	bliss_bitpacker_t *packer;
+	uint16_t value;
+
+	packer = bliss_bitpacker_create(16);
+	ck_assert(!packer->write_bits(packer, 0, 17));
+	ck_assert( packer->write_bits(packer, 0x7f01, 15));
+	ck_assert(!packer->write_bits(packer, 3,  2));
+	packer->destroy(packer);
+
+	packer = bliss_bitpacker_create_from_data(chunk_from_chars(0x7f, 0x01));
+	ck_assert(!packer->read_bits(packer, &value, 17));
+	ck_assert( packer->read_bits(packer, &value, 15));
+	ck_assert(!packer->read_bits(packer, &value,  2));
+	packer->destroy(packer);
+}
+END_TEST
+
+Suite *bliss_bitpacker_suite_create()
+{
+	Suite *s;
+	TCase *tc;
+
+	s = suite_create("bliss_bitpacker");
+
+	tc = tcase_create("bitpacker_write");
+	tcase_add_test(tc, test_bliss_sign_bitpacker_write);
+	suite_add_tcase(s, tc);
+
+	tc = tcase_create("bitpacker_read");
+	tcase_add_test(tc, test_bliss_sign_bitpacker_read);
+	suite_add_tcase(s, tc);
+
+	tc = tcase_create("bitpacker_fail");
+	tcase_add_test(tc, test_bliss_sign_bitpacker_fail);
+	suite_add_tcase(s, tc);
+
+	return s;
+}