diff options
Diffstat (limited to 'thirdparty/mbedtls/library/dhm.c')
| -rw-r--r-- | thirdparty/mbedtls/library/dhm.c | 89 |
1 files changed, 71 insertions, 18 deletions
diff --git a/thirdparty/mbedtls/library/dhm.c b/thirdparty/mbedtls/library/dhm.c index 8255632a99..d652cf0ac9 100644 --- a/thirdparty/mbedtls/library/dhm.c +++ b/thirdparty/mbedtls/library/dhm.c @@ -1,8 +1,14 @@ /* * Diffie-Hellman-Merkle key exchange * - * Copyright (C) 2006-2015, ARM Limited, All Rights Reserved - * SPDX-License-Identifier: Apache-2.0 + * Copyright The Mbed TLS Contributors + * SPDX-License-Identifier: Apache-2.0 OR GPL-2.0-or-later + * + * This file is provided under the Apache License 2.0, or the + * GNU General Public License v2.0 or later. + * + * ********** + * Apache License 2.0: * * Licensed under the Apache License, Version 2.0 (the "License"); you may * not use this file except in compliance with the License. @@ -16,7 +22,26 @@ * See the License for the specific language governing permissions and * limitations under the License. * - * This file is part of mbed TLS (https://tls.mbed.org) + * ********** + * + * ********** + * GNU General Public License v2.0 or later: + * + * 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. + * + * 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. + * + * You should have received a copy of the GNU General Public License along + * with this program; if not, write to the Free Software Foundation, Inc., + * 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA. + * + * ********** */ /* * The following sources were referenced in the design of this implementation @@ -324,6 +349,32 @@ cleanup: } /* + * Pick a random R in the range [2, M) for blinding purposes + */ +static int dhm_random_below( mbedtls_mpi *R, const mbedtls_mpi *M, + int (*f_rng)(void *, unsigned char *, size_t), void *p_rng ) +{ + int ret, count; + + count = 0; + do + { + MBEDTLS_MPI_CHK( mbedtls_mpi_fill_random( R, mbedtls_mpi_size( M ), f_rng, p_rng ) ); + + while( mbedtls_mpi_cmp_mpi( R, M ) >= 0 ) + MBEDTLS_MPI_CHK( mbedtls_mpi_shift_r( R, 1 ) ); + + if( count++ > 10 ) + return( MBEDTLS_ERR_MPI_NOT_ACCEPTABLE ); + } + while( mbedtls_mpi_cmp_int( R, 1 ) <= 0 ); + +cleanup: + return( ret ); +} + + +/* * Use the blinding method and optimisation suggested in section 10 of: * KOCHER, Paul C. Timing attacks on implementations of Diffie-Hellman, RSA, * DSS, and other systems. In : Advances in Cryptology-CRYPTO'96. Springer @@ -332,7 +383,10 @@ cleanup: static int dhm_update_blinding( mbedtls_dhm_context *ctx, int (*f_rng)(void *, unsigned char *, size_t), void *p_rng ) { - int ret, count; + int ret; + mbedtls_mpi R; + + mbedtls_mpi_init( &R ); /* * Don't use any blinding the first time a particular X is used, @@ -367,24 +421,23 @@ static int dhm_update_blinding( mbedtls_dhm_context *ctx, */ /* Vi = random( 2, P-1 ) */ - count = 0; - do - { - MBEDTLS_MPI_CHK( mbedtls_mpi_fill_random( &ctx->Vi, mbedtls_mpi_size( &ctx->P ), f_rng, p_rng ) ); + MBEDTLS_MPI_CHK( dhm_random_below( &ctx->Vi, &ctx->P, f_rng, p_rng ) ); + + /* Vf = Vi^-X mod P + * First compute Vi^-1 = R * (R Vi)^-1, (avoiding leaks from inv_mod), + * then elevate to the Xth power. */ + MBEDTLS_MPI_CHK( dhm_random_below( &R, &ctx->P, f_rng, p_rng ) ); + MBEDTLS_MPI_CHK( mbedtls_mpi_mul_mpi( &ctx->Vf, &ctx->Vi, &R ) ); + MBEDTLS_MPI_CHK( mbedtls_mpi_mod_mpi( &ctx->Vf, &ctx->Vf, &ctx->P ) ); + MBEDTLS_MPI_CHK( mbedtls_mpi_inv_mod( &ctx->Vf, &ctx->Vf, &ctx->P ) ); + MBEDTLS_MPI_CHK( mbedtls_mpi_mul_mpi( &ctx->Vf, &ctx->Vf, &R ) ); + MBEDTLS_MPI_CHK( mbedtls_mpi_mod_mpi( &ctx->Vf, &ctx->Vf, &ctx->P ) ); - while( mbedtls_mpi_cmp_mpi( &ctx->Vi, &ctx->P ) >= 0 ) - MBEDTLS_MPI_CHK( mbedtls_mpi_shift_r( &ctx->Vi, 1 ) ); - - if( count++ > 10 ) - return( MBEDTLS_ERR_MPI_NOT_ACCEPTABLE ); - } - while( mbedtls_mpi_cmp_int( &ctx->Vi, 1 ) <= 0 ); - - /* Vf = Vi^-X mod P */ - MBEDTLS_MPI_CHK( mbedtls_mpi_inv_mod( &ctx->Vf, &ctx->Vi, &ctx->P ) ); MBEDTLS_MPI_CHK( mbedtls_mpi_exp_mod( &ctx->Vf, &ctx->Vf, &ctx->X, &ctx->P, &ctx->RP ) ); cleanup: + mbedtls_mpi_free( &R ); + return( ret ); } |