113 lines
3.9 KiB
C
113 lines
3.9 KiB
C
/**
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*
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* <gf2x_arith.h>
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*
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* @version 2.0 (March 2019)
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*
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* Reference ISO-C11 Implementation of the LEDAcrypt KEM-LT cipher using GCC built-ins.
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*
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* In alphabetical order:
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*
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* @author Marco Baldi <m.baldi@univpm.it>
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* @author Alessandro Barenghi <alessandro.barenghi@polimi.it>
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* @author Franco Chiaraluce <f.chiaraluce@univpm.it>
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* @author Gerardo Pelosi <gerardo.pelosi@polimi.it>
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* @author Paolo Santini <p.santini@pm.univpm.it>
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*
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* This code is hereby placed in the public domain.
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*
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* THIS SOFTWARE IS PROVIDED BY THE AUTHORS ''AS IS'' AND ANY EXPRESS
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* OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
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* WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
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* ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHORS OR CONTRIBUTORS BE
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* LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
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* CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
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* SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR
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* BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY,
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* WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE
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* OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE,
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* EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
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*
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**/
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#pragma once
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#include "gf2x_limbs.h"
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/*----------------------------------------------------------------------------*/
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/*
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* Elements of GF(2)[x] are stored in compact dense binary form.
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*
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* Each bit in a byte is assumed to be the coefficient of a binary
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* polynomial f(x), in Big-Endian format (i.e., reading everything from
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* left to right, the most significant element is met first):
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*
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* byte:(0000 0000) == 0x00 ... f(x) == 0
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* byte:(0000 0001) == 0x01 ... f(x) == 1
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* byte:(0000 0010) == 0x02 ... f(x) == x
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* byte:(0000 0011) == 0x03 ... f(x) == x+1
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* ... ... ...
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* byte:(0000 1111) == 0x0F ... f(x) == x^{3}+x^{2}+x+1
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* ... ... ...
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* byte:(1111 1111) == 0xFF ... f(x) == x^{7}+x^{6}+x^{5}+x^{4}+x^{3}+x^{2}+x+1
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*
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*
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* A "machine word" (A_i) is considered as a DIGIT.
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* Bytes in a DIGIT are assumed in Big-Endian format:
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* E.g., if sizeof(DIGIT) == 4:
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* A_i: A_{i,3} A_{i,2} A_{i,1} A_{i,0}.
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* A_{i,3} denotes the most significant byte, A_{i,0} the least significant one.
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* f(x) == x^{31} + ... + x^{24} +
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* + x^{23} + ... + x^{16} +
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* + x^{15} + ... + x^{8} +
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* + x^{7} + ... + x^{0}
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*
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*
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* Multi-precision elements (i.e., with multiple DIGITs) are stored in
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* Big-endian format:
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* A = A_{n-1} A_{n-2} ... A_1 A_0
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*
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* position[A_{n-1}] == 0
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* position[A_{n-2}] == 1
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* ...
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* position[A_{1}] == n-2
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* position[A_{0}] == n-1
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*/
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/*----------------------------------------------------------------------------*/
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#define TC3
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#if defined(TC3)
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#define GF2X_MUL gf2x_mul_TC3
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#else
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#define GF2X_MUL gf2x_mul_comb
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#endif
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/*----------------------------------------------------------------------------*/
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static inline void gf2x_add(const int nr, DIGIT Res[],
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const int na, const DIGIT A[],
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const int nb, const DIGIT B[]) {
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for (unsigned i = 0; i < nr; i++) {
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Res[i] = A[i] ^ B[i];
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}
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} // end gf2x_add
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/*----------------------------------------------------------------------------*/
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void GF2X_MUL(const int nr, DIGIT Res[],
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const int na, const DIGIT A[],
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const int nb, const DIGIT B[]
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);
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int gf2x_cmp(const unsigned lenA, const DIGIT A[],
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const unsigned lenB, const DIGIT B[]);
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/* PRE: MAX ALLOWED ROTATION AMOUNT : DIGIT_SIZE_b */
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void right_bit_shift_n(const int length, DIGIT in[], const int amount);
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/* PRE: MAX ALLOWED ROTATION AMOUNT : DIGIT_SIZE_b */
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void left_bit_shift_n(const int length, DIGIT in[], const int amount);
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/*----------------------------------------------------------------------------*/
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