aacf29b8aa
Reviewed-by: Bernd Edlinger <bernd.edlinger@hotmail.de> (Merged from https://github.com/openssl/openssl/pull/5105)
92 lines
2.1 KiB
C
92 lines
2.1 KiB
C
/**
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* @file field.h
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* @brief Generic gf header.
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* @copyright
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* Copyright (c) 2014 Cryptography Research, Inc. \n
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* Released under the MIT License. See LICENSE.txt for license information.
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* @author Mike Hamburg
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*/
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#ifndef __GF_H__
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#define __GF_H__
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#include "constant_time.h"
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#include "f_field.h"
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#include <string.h>
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/** Square x, n times. */
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static ossl_inline void gf_sqrn (
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gf_s *__restrict__ y,
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const gf x,
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int n
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) {
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gf tmp;
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assert(n>0);
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if (n&1) {
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gf_sqr(y,x);
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n--;
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} else {
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gf_sqr(tmp,x);
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gf_sqr(y,tmp);
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n-=2;
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}
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for (; n; n-=2) {
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gf_sqr(tmp,y);
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gf_sqr(y,tmp);
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}
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}
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#define gf_add_nr gf_add_RAW
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/** Subtract mod p. Bias by 2 and don't reduce */
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static inline void gf_sub_nr ( gf c, const gf a, const gf b ) {
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gf_sub_RAW(c,a,b);
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gf_bias(c, 2);
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if (GF_HEADROOM < 3) gf_weak_reduce(c);
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}
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/** Subtract mod p. Bias by amt but don't reduce. */
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static inline void gf_subx_nr ( gf c, const gf a, const gf b, int amt ) {
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gf_sub_RAW(c,a,b);
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gf_bias(c, amt);
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if (GF_HEADROOM < amt+1) gf_weak_reduce(c);
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}
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/** Mul by signed int. Not constant-time WRT the sign of that int. */
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static inline void gf_mulw(gf c, const gf a, int32_t w) {
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if (w>0) {
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gf_mulw_unsigned(c, a, w);
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} else {
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gf_mulw_unsigned(c, a, -w);
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gf_sub(c,ZERO,c);
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}
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}
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/** Constant time, x = is_z ? z : y */
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static inline void gf_cond_sel(gf x, const gf y, const gf z, mask_t is_z) {
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constant_time_select(x,y,z,sizeof(gf),is_z,0);
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}
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/** Constant time, if (neg) x=-x; */
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static inline void gf_cond_neg(gf x, mask_t neg) {
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gf y;
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gf_sub(y,ZERO,x);
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gf_cond_sel(x,x,y,neg);
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}
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/** Constant time, if (swap) (x,y) = (y,x); */
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static inline void
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gf_cond_swap(gf x, gf_s *__restrict__ y, mask_t swap) {
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constant_time_cond_swap(x,y,sizeof(gf_s),swap);
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}
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static ossl_inline void gf_mul_qnr(gf_s *__restrict__ out, const gf x) {
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gf_sub(out,ZERO,x);
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}
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static ossl_inline void gf_div_qnr(gf_s *__restrict__ out, const gf x) {
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gf_sub(out,ZERO,x);
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}
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#endif // __GF_H__
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