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gnupg/include/mpi.h
NIIBE Yutaka 6cbc75e712 mpi: Avoid data-dependent timing variations in mpi_powm.
* include/mpi.h, mpi/mpiutils.c (mpi_set_cond): New.
* mpi/mpi-pow.c (SIZE_PRECOMP): Rename from SIZE_B_2I3.
(mpi_powm): Access all data in the table and use mpi_set_cond.

--

Access to the precomputed table was indexed by a portion of EXPO,
which could be mounted by a side channel attack.  This change fixes
this particular data-dependent access pattern.
2015-02-26 21:00:05 +09:00

171 lines
5.9 KiB
C

/* mpi.h - Multi Precision Integers
* Copyright (C) 1994, 1996, 1998, 1999,
* 2000, 2001 Free Software Foundation, Inc.
*
* This file is part of GNUPG.
*
* GNUPG 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 3 of the License, or
* (at your option) any later version.
*
* GNUPG 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.
*
* You should have received a copy of the GNU General Public License
* along with this program; if not, see <http://www.gnu.org/licenses/>.
*
* Note: This code is heavily based on the GNU MP Library.
* Actually it's the same code with only minor changes in the
* way the data is stored; this is to support the abstraction
* of an optional secure memory allocation which may be used
* to avoid revealing of sensitive data due to paging etc.
* The GNU MP Library itself is published under the LGPL;
* however I decided to publish this code under the plain GPL.
*/
#ifndef G10_MPI_H
#define G10_MPI_H
#include <config.h>
#include <stdio.h>
#include "iobuf.h"
#include "types.h"
#include "memory.h"
#ifndef EXTERN_UNLESS_MAIN_MODULE
#if defined (__riscos__) && !defined (INCLUDED_BY_MAIN_MODULE)
#define EXTERN_UNLESS_MAIN_MODULE extern
#else
#define EXTERN_UNLESS_MAIN_MODULE
#endif
#endif
#define DBG_MPI mpi_debug_mode
EXTERN_UNLESS_MAIN_MODULE int mpi_debug_mode;
struct gcry_mpi;
typedef struct gcry_mpi *MPI;
/*-- mpiutil.c --*/
#ifdef M_DEBUG
#define mpi_alloc(n) mpi_debug_alloc((n), M_DBGINFO( __LINE__ ) )
#define mpi_alloc_secure(n) mpi_debug_alloc_secure((n), M_DBGINFO( __LINE__ ) )
#define mpi_alloc_like(n) mpi_debug_alloc_like((n), M_DBGINFO( __LINE__ ) )
#define mpi_free(a) mpi_debug_free((a), M_DBGINFO(__LINE__) )
#define mpi_resize(a,b) mpi_debug_resize((a),(b), M_DBGINFO(__LINE__) )
#define mpi_copy(a) mpi_debug_copy((a), M_DBGINFO(__LINE__) )
MPI mpi_debug_alloc( unsigned nlimbs, const char *info );
MPI mpi_debug_alloc_secure( unsigned nlimbs, const char *info );
MPI mpi_debug_alloc_like( MPI a, const char *info );
void mpi_debug_free( MPI a, const char *info );
void mpi_debug_resize( MPI a, unsigned nlimbs, const char *info );
MPI mpi_debug_copy( MPI a, const char *info );
#else
MPI mpi_alloc( unsigned nlimbs );
MPI mpi_alloc_secure( unsigned nlimbs );
MPI mpi_alloc_like( MPI a );
void mpi_free( MPI a );
void mpi_resize( MPI a, unsigned nlimbs );
MPI mpi_copy( MPI a );
#endif
#define mpi_is_opaque(a) ((a) && (mpi_get_flags (a)&4))
MPI mpi_set_opaque( MPI a, void *p, unsigned int len );
void *mpi_get_opaque( MPI a, unsigned int *len );
#define mpi_is_secure(a) ((a) && (mpi_get_flags (a)&1))
void mpi_set_secure( MPI a );
void mpi_clear( MPI a );
void mpi_set( MPI w, MPI u);
void mpi_set_cond( MPI w, MPI u, unsigned long set);
void mpi_set_ui( MPI w, ulong u);
MPI mpi_alloc_set_ui( unsigned long u);
void mpi_m_check( MPI a );
void mpi_swap( MPI a, MPI b);
int mpi_get_nlimbs (MPI a);
int mpi_is_neg (MPI a);
unsigned int mpi_nlimb_hint_from_nbytes (unsigned int nbytes);
unsigned int mpi_nlimb_hint_from_nbits (unsigned int nbits);
unsigned int mpi_get_flags (MPI a);
/*-- mpicoder.c --*/
int mpi_write( IOBUF out, MPI a );
#ifdef M_DEBUG
#define mpi_read(a,b,c) mpi_debug_read((a),(b),(c), M_DBGINFO( __LINE__ ) )
MPI mpi_debug_read(IOBUF inp, unsigned *nread, int secure, const char *info);
#else
MPI mpi_read(IOBUF inp, unsigned *nread, int secure);
#endif
MPI mpi_read_from_buffer(byte *buffer, unsigned *ret_nread, int secure);
int mpi_fromstr(MPI val, const char *str);
int mpi_print( FILE *fp, MPI a, int mode );
void g10_log_mpidump( const char *text, MPI a );
u32 mpi_get_keyid( MPI a, u32 *keyid );
byte *mpi_get_buffer( MPI a, unsigned *nbytes, int *sign );
byte *mpi_get_secure_buffer( MPI a, unsigned *nbytes, int *sign );
void mpi_set_buffer( MPI a, const byte *buffer, unsigned nbytes, int sign );
#define log_mpidump g10_log_mpidump
/*-- mpi-add.c --*/
void mpi_add_ui(MPI w, MPI u, ulong v );
void mpi_add(MPI w, MPI u, MPI v);
void mpi_addm(MPI w, MPI u, MPI v, MPI m);
void mpi_sub_ui(MPI w, MPI u, ulong v );
void mpi_sub( MPI w, MPI u, MPI v);
void mpi_subm( MPI w, MPI u, MPI v, MPI m);
/*-- mpi-mul.c --*/
void mpi_mul_ui(MPI w, MPI u, ulong v );
void mpi_mul_2exp( MPI w, MPI u, ulong cnt);
void mpi_mul( MPI w, MPI u, MPI v);
void mpi_mulm( MPI w, MPI u, MPI v, MPI m);
/*-- mpi-div.c --*/
ulong mpi_fdiv_r_ui( MPI rem, MPI dividend, ulong divisor );
void mpi_fdiv_r( MPI rem, MPI dividend, MPI divisor );
void mpi_fdiv_q( MPI quot, MPI dividend, MPI divisor );
void mpi_fdiv_qr( MPI quot, MPI rem, MPI dividend, MPI divisor );
void mpi_tdiv_r( MPI rem, MPI num, MPI den);
void mpi_tdiv_qr( MPI quot, MPI rem, MPI num, MPI den);
void mpi_tdiv_q_2exp( MPI w, MPI u, unsigned count );
int mpi_divisible_ui(MPI dividend, ulong divisor );
/*-- mpi-gcd.c --*/
int mpi_gcd( MPI g, MPI a, MPI b );
/*-- mpi-pow.c --*/
void mpi_pow( MPI w, MPI u, MPI v);
void mpi_powm( MPI res, MPI base, MPI exponent, MPI mod);
/*-- mpi-mpow.c --*/
void mpi_mulpowm( MPI res, MPI *basearray, MPI *exparray, MPI mod);
/*-- mpi-cmp.c --*/
int mpi_cmp_ui( MPI u, ulong v );
int mpi_cmp( MPI u, MPI v );
/*-- mpi-scan.c --*/
int mpi_getbyte( MPI a, unsigned idx );
void mpi_putbyte( MPI a, unsigned idx, int value );
unsigned mpi_trailing_zeros( MPI a );
/*-- mpi-bit.c --*/
void mpi_normalize( MPI a );
unsigned mpi_get_nbits( MPI a );
int mpi_test_bit( MPI a, unsigned n );
void mpi_set_bit( MPI a, unsigned n );
void mpi_set_highbit( MPI a, unsigned n );
void mpi_clear_highbit( MPI a, unsigned n );
void mpi_clear_bit( MPI a, unsigned n );
void mpi_rshift( MPI x, MPI a, unsigned n );
/*-- mpi-inv.c --*/
void mpi_invm( MPI x, MPI u, MPI v );
#endif /*G10_MPI_H*/