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pqcrypto/crypto_kem/ledakemlt12/clean/gf2x_arith.h

113 lines
3.9 KiB
C

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