Merge pull request #4297 from gilles-peskine-arm/ecp-add-fix-202104

Fix ECP arithmetic bug and read of zero-padded negative number
This commit is contained in:
Gilles Peskine 2021-04-09 16:46:06 +02:00 committed by GitHub
commit 9a1c092f8b
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GPG key ID: 4AEE18F83AFDEB23
8 changed files with 330 additions and 34 deletions

View file

@ -470,6 +470,7 @@ int mbedtls_mpi_read_string( mbedtls_mpi *X, int radix, const char *s )
{
int ret = MBEDTLS_ERR_ERROR_CORRUPTION_DETECTED;
size_t i, j, slen, n;
int sign = 1;
mbedtls_mpi_uint d;
mbedtls_mpi T;
MPI_VALIDATE_RET( X != NULL );
@ -480,6 +481,12 @@ int mbedtls_mpi_read_string( mbedtls_mpi *X, int radix, const char *s )
mbedtls_mpi_init( &T );
if( s[0] == '-' )
{
++s;
sign = -1;
}
slen = strlen( s );
if( radix == 16 )
@ -494,12 +501,6 @@ int mbedtls_mpi_read_string( mbedtls_mpi *X, int radix, const char *s )
for( i = slen, j = 0; i > 0; i--, j++ )
{
if( i == 1 && s[i - 1] == '-' )
{
X->s = -1;
break;
}
MBEDTLS_MPI_CHK( mpi_get_digit( &d, radix, s[i - 1] ) );
X->p[j / ( 2 * ciL )] |= d << ( ( j % ( 2 * ciL ) ) << 2 );
}
@ -510,26 +511,15 @@ int mbedtls_mpi_read_string( mbedtls_mpi *X, int radix, const char *s )
for( i = 0; i < slen; i++ )
{
if( i == 0 && s[i] == '-' )
{
X->s = -1;
continue;
}
MBEDTLS_MPI_CHK( mpi_get_digit( &d, radix, s[i] ) );
MBEDTLS_MPI_CHK( mbedtls_mpi_mul_int( &T, X, radix ) );
if( X->s == 1 )
{
MBEDTLS_MPI_CHK( mbedtls_mpi_add_int( X, &T, d ) );
}
else
{
MBEDTLS_MPI_CHK( mbedtls_mpi_sub_int( X, &T, d ) );
}
MBEDTLS_MPI_CHK( mbedtls_mpi_add_int( X, &T, d ) );
}
}
if( sign < 0 && mbedtls_mpi_bitlen( X ) != 0 )
X->s = -1;
cleanup:
mbedtls_mpi_free( &T );

View file

@ -77,6 +77,8 @@
#include "mbedtls/platform_util.h"
#include "mbedtls/error.h"
#include "ecp_invasive.h"
#include <string.h>
#if !defined(MBEDTLS_ECP_ALT)

View file

@ -25,6 +25,8 @@
#include "mbedtls/platform_util.h"
#include "mbedtls/error.h"
#include "ecp_invasive.h"
#include <string.h>
#if !defined(MBEDTLS_ECP_ALT)
@ -1028,26 +1030,35 @@ static inline void sub32( uint32_t *dst, uint32_t src, signed char *carry )
STORE32; i++; \
cur = c > 0 ? c : 0; STORE32; \
cur = 0; while( ++i < MAX32 ) { STORE32; } \
if( c < 0 ) fix_negative( N, c, bits );
if( c < 0 ) mbedtls_ecp_fix_negative( N, c, bits );
/*
* If the result is negative, we get it in the form
* c * 2^(bits + 32) + N, with c negative and N positive shorter than 'bits'
* c * 2^bits + N, with c negative and N positive shorter than 'bits'
*/
static inline void fix_negative( mbedtls_mpi *N, signed char c, size_t bits )
MBEDTLS_STATIC_TESTABLE
void mbedtls_ecp_fix_negative( mbedtls_mpi *N, signed char c, size_t bits )
{
size_t i;
/* Set N := N - 2^bits */
--N->p[0];
/* Set N := 2^bits - 1 - N. We know that 0 <= N < 2^bits, so
* set the absolute value to 0xfff...fff - N. There is no carry
* since we're subtracting from all-bits-one. */
for( i = 0; i <= bits / 8 / sizeof( mbedtls_mpi_uint ); i++ )
{
N->p[i] = ~(mbedtls_mpi_uint)0 - N->p[i];
}
/* Add 1, taking care of the carry. */
i = 0;
do
++N->p[i];
while( N->p[i++] == 0 && i <= bits / 8 / sizeof( mbedtls_mpi_uint ) );
/* Invert the sign.
* Now N = N0 - 2^bits where N0 is the initial value of N. */
N->s = -1;
/* Add |c| * 2^(bits + 32) to the absolute value. Since c and N are
* negative, this adds c * 2^(bits + 32). */
/* Add |c| * 2^bits to the absolute value. Since c and N are
* negative, this adds c * 2^bits. */
mbedtls_mpi_uint msw = (mbedtls_mpi_uint) -c;
#if defined(MBEDTLS_HAVE_INT64)
if( bits == 224 )

51
library/ecp_invasive.h Normal file
View file

@ -0,0 +1,51 @@
/**
* \file ecp_invasive.h
*
* \brief ECP module: interfaces for invasive testing only.
*
* The interfaces in this file are intended for testing purposes only.
* They SHOULD NOT be made available in library integrations except when
* building the library for testing.
*/
/*
* Copyright The Mbed TLS Contributors
* SPDX-License-Identifier: Apache-2.0
*
* Licensed under the Apache License, Version 2.0 (the "License"); you may
* not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
* WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
#ifndef MBEDTLS_ECP_INVASIVE_H
#define MBEDTLS_ECP_INVASIVE_H
#include "common.h"
#include "mbedtls/ecp.h"
#if defined(MBEDTLS_TEST_HOOKS) && defined(MBEDTLS_ECP_C)
#if defined(MBEDTLS_ECP_DP_SECP224R1_ENABLED) || \
defined(MBEDTLS_ECP_DP_SECP256R1_ENABLED) || \
defined(MBEDTLS_ECP_DP_SECP384R1_ENABLED)
/* Preconditions:
* - bits is a multiple of 64 or is 224
* - c is -1 or -2
* - 0 <= N < 2^bits
* - N has room for bits plus one limb
*
* Behavior:
* Set N to c * 2^bits + old_value_of_N.
*/
void mbedtls_ecp_fix_negative( mbedtls_mpi *N, signed char c, size_t bits );
#endif
#endif /* MBEDTLS_TEST_HOOKS && MBEDTLS_ECP_C */
#endif /* MBEDTLS_ECP_INVASIVE_H */

View file

@ -458,6 +458,14 @@ ECP point multiplication rng fail Curve25519
depends_on:MBEDTLS_ECP_DP_CURVE25519_ENABLED
ecp_test_mul_rng:MBEDTLS_ECP_DP_CURVE25519:"5AC99F33632E5A768DE7E81BF854C27C46E3FBF2ABBACD29EC4AFF517369C660"
ECP point muladd secp256r1 #1
depends_on:MBEDTLS_ECP_DP_SECP256R1_ENABLED
ecp_muladd:MBEDTLS_ECP_DP_SECP256R1:"01":"04e1e1e1e1e1e1e1e1e1e1e1e1e1e1e1e1e1e1e1e1e1e0e1ff20e1ffe120e1e1e173287170a761308491683e345cacaebb500c96e1a7bbd37772968b2c951f0579":"01":"04e1e1e1e1e1e1e1e1e1e1e1e1e1e1e1e1e1e1e1e1e1ffffffff20e120e1e1e1e13a4e135157317b79d4ecf329fed4f9eb00dc67dbddae33faca8b6d8a0255b5ce":"04fab65e09aa5dd948320f86246be1d3fc571e7f799d9005170ed5cc868b67598431a668f96aa9fd0b0eb15f0edf4c7fe1be2885eadcb57e3db4fdd093585d3fa6"
ECP point muladd secp256r1 #2
depends_on:MBEDTLS_ECP_DP_SECP256R1_ENABLED
ecp_muladd:MBEDTLS_ECP_DP_SECP256R1:"01":"04e1e1e1e1e1e1e1e1e1e1e1e1e1e1e1e1e1e1e1e1e1ffffffff20e120e1e1e1e13a4e135157317b79d4ecf329fed4f9eb00dc67dbddae33faca8b6d8a0255b5ce":"01":"04e1e1e1e1e1e1e1e1e1e1e1e1e1e1e1e1e1e1e1e1e1e0e1ff20e1ffe120e1e1e173287170a761308491683e345cacaebb500c96e1a7bbd37772968b2c951f0579":"04fab65e09aa5dd948320f86246be1d3fc571e7f799d9005170ed5cc868b67598431a668f96aa9fd0b0eb15f0edf4c7fe1be2885eadcb57e3db4fdd093585d3fa6"
ECP test vectors Curve448 (RFC 7748 6.2, after decodeUCoordinate)
depends_on:MBEDTLS_ECP_DP_CURVE448_ENABLED
ecp_test_vec_x:MBEDTLS_ECP_DP_CURVE448:"eb7298a5c0d8c29a1dab27f1a6826300917389449741a974f5bac9d98dc298d46555bce8bae89eeed400584bb046cf75579f51d125498f98":"a01fc432e5807f17530d1288da125b0cd453d941726436c8bbd9c5222c3da7fa639ce03db8d23b274a0721a1aed5227de6e3b731ccf7089b":"ad997351b6106f36b0d1091b929c4c37213e0d2b97e85ebb20c127691d0dad8f1d8175b0723745e639a3cb7044290b99e0e2a0c27a6a301c":"0936f37bc6c1bd07ae3dec7ab5dc06a73ca13242fb343efc72b9d82730b445f3d4b0bd077162a46dcfec6f9b590bfcbcf520cdb029a8b73e":"9d874a5137509a449ad5853040241c5236395435c36424fd560b0cb62b281d285275a740ce32a22dd1740f4aa9161cec95ccc61a18f4ff07"
@ -508,3 +516,127 @@ ecp_muladd_restart:MBEDTLS_ECP_DP_SECP256R1:"CB28E0999B9C7715FD0A80D8E47A7707971
ECP restartable muladd secp256r1 max_ops=250
depends_on:MBEDTLS_ECP_DP_SECP256R1_ENABLED
ecp_muladd_restart:MBEDTLS_ECP_DP_SECP256R1:"CB28E0999B9C7715FD0A80D8E47A77079716CBBF917DD72E97566EA1C066957C":"2B57C0235FB7489768D058FF4911C20FDBE71E3699D91339AFBB903EE17255DC":"C3875E57C85038A0D60370A87505200DC8317C8C534948BEA6559C7C18E6D4CE":"3B4E49C4FDBFC006FF993C81A50EAE221149076D6EC09DDD9FB3B787F85B6483":"2442A5CC0ECD015FA3CA31DC8E2BBC70BF42D60CBCA20085E0822CB04235E970":"6FC98BD7E50211A4A27102FA3549DF79EBCB4BF246B80945CDDFE7D509BBFD7D":250:4:64
ECP fix_negative: 0, -1, 224
fix_negative:"00":-1:224
ECP fix_negative: 1, -1, 224
fix_negative:"01":-1:224
ECP fix_negative: 2^32-1, -1, 224
fix_negative:"ffffffff":-1:224
ECP fix_negative: 2^32, -1, 224
fix_negative:"0100000000":-1:224
ECP fix_negative: 2^64-1, -1, 224
fix_negative:"ffffffffffffffff":-1:224
ECP fix_negative: 2^64, -1, 224
fix_negative:"010000000000000000":-1:224
ECP fix_negative: 2^128-1, -1, 224
fix_negative:"ffffffffffffffffffffffffffffffff":-1:224
ECP fix_negative: 2^128, -1, 224
fix_negative:"0100000000000000000000000000000000":-1:224
ECP fix_negative: 2^128+1, -1, 224
fix_negative:"0100000000000000000000000000000001":-1:224
ECP fix_negative: 2^224-1, -1, 224
fix_negative:"ffffffffffffffffffffffffffffffffffffffffffffffffffffffff":-1:224
ECP fix_negative: 0, -2, 224
fix_negative:"00":-2:224
ECP fix_negative: 1, -2, 224
fix_negative:"01":-2:224
ECP fix_negative: 2^32-1, -2, 224
fix_negative:"ffffffff":-2:224
ECP fix_negative: 2^32, -2, 224
fix_negative:"0100000000":-2:224
ECP fix_negative: 2^64-1, -2, 224
fix_negative:"ffffffffffffffff":-2:224
ECP fix_negative: 2^64, -2, 224
fix_negative:"010000000000000000":-2:224
ECP fix_negative: 2^128-1, -2, 224
fix_negative:"ffffffffffffffffffffffffffffffff":-2:224
ECP fix_negative: 2^128, -2, 224
fix_negative:"0100000000000000000000000000000000":-2:224
ECP fix_negative: 2^128+1, -2, 224
fix_negative:"0100000000000000000000000000000001":-2:224
ECP fix_negative: 2^224-1, -2, 224
fix_negative:"ffffffffffffffffffffffffffffffffffffffffffffffffffffffff":-2:224
ECP fix_negative: 0, -1, 256
fix_negative:"00":-1:256
ECP fix_negative: 1, -1, 256
fix_negative:"01":-1:256
ECP fix_negative: 2^32-1, -1, 256
fix_negative:"ffffffff":-1:256
ECP fix_negative: 2^32, -1, 256
fix_negative:"0100000000":-1:256
ECP fix_negative: 2^64-1, -1, 256
fix_negative:"ffffffffffffffff":-1:256
ECP fix_negative: 2^64, -1, 256
fix_negative:"010000000000000000":-1:256
ECP fix_negative: 2^128-1, -1, 256
fix_negative:"ffffffffffffffffffffffffffffffff":-1:256
ECP fix_negative: 2^128, -1, 256
fix_negative:"0100000000000000000000000000000000":-1:256
ECP fix_negative: 2^128+1, -1, 256
fix_negative:"0100000000000000000000000000000001":-1:256
ECP fix_negative: 2^256-1, -1, 256
fix_negative:"ffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffff":-1:256
ECP fix_negative: 0, -2, 256
fix_negative:"00":-2:256
ECP fix_negative: 1, -2, 256
fix_negative:"01":-2:256
ECP fix_negative: 2^32-1, -2, 256
fix_negative:"ffffffff":-2:256
ECP fix_negative: 2^32, -2, 256
fix_negative:"0100000000":-2:256
ECP fix_negative: 2^64-1, -2, 256
fix_negative:"ffffffffffffffff":-2:256
ECP fix_negative: 2^64, -2, 256
fix_negative:"010000000000000000":-2:256
ECP fix_negative: 2^128-1, -2, 256
fix_negative:"ffffffffffffffffffffffffffffffff":-2:256
ECP fix_negative: 2^128, -2, 256
fix_negative:"0100000000000000000000000000000000":-2:256
ECP fix_negative: 2^128+1, -2, 256
fix_negative:"0100000000000000000000000000000001":-2:256
ECP fix_negative: 2^256-1, -2, 256
fix_negative:"ffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffff":-2:256
# The first call to fix_negative in the test case of issue #4296.
ECP fix_negative: #4296.1
fix_negative:"8A4DD4C8B42C5EAED15FE4F4579F4CE513EC90A94010BF000000000000000000":-1:256

View file

@ -1,6 +1,15 @@
/* BEGIN_HEADER */
#include "mbedtls/ecp.h"
#include "ecp_invasive.h"
#if defined(MBEDTLS_TEST_HOOKS) && \
( defined(MBEDTLS_ECP_DP_SECP224R1_ENABLED) || \
defined(MBEDTLS_ECP_DP_SECP256R1_ENABLED) || \
defined(MBEDTLS_ECP_DP_SECP384R1_ENABLED) )
#define HAVE_FIX_NEGATIVE
#endif
#define ECP_PF_UNKNOWN -1
#define ECP_PT_RESET( x ) \
@ -752,6 +761,52 @@ exit:
}
/* END_CASE */
/* BEGIN_CASE depends_on:MBEDTLS_ECP_SHORT_WEIERSTRASS_ENABLED */
void ecp_muladd( int id,
data_t *u1_bin, data_t *P1_bin,
data_t *u2_bin, data_t *P2_bin,
data_t *expected_result )
{
/* Compute R = u1 * P1 + u2 * P2 */
mbedtls_ecp_group grp;
mbedtls_ecp_point P1, P2, R;
mbedtls_mpi u1, u2;
uint8_t actual_result[MBEDTLS_ECP_MAX_PT_LEN];
size_t len;
mbedtls_ecp_group_init( &grp );
mbedtls_ecp_point_init( &P1 );
mbedtls_ecp_point_init( &P2 );
mbedtls_ecp_point_init( &R );
mbedtls_mpi_init( &u1 );
mbedtls_mpi_init( &u2 );
TEST_EQUAL( 0, mbedtls_ecp_group_load( &grp, id ) );
TEST_EQUAL( 0, mbedtls_mpi_read_binary( &u1, u1_bin->x, u1_bin->len ) );
TEST_EQUAL( 0, mbedtls_mpi_read_binary( &u2, u2_bin->x, u2_bin->len ) );
TEST_EQUAL( 0, mbedtls_ecp_point_read_binary( &grp, &P1,
P1_bin->x, P1_bin->len ) );
TEST_EQUAL( 0, mbedtls_ecp_point_read_binary( &grp, &P2,
P2_bin->x, P2_bin->len ) );
TEST_EQUAL( 0, mbedtls_ecp_muladd( &grp, &R, &u1, &P1, &u2, &P2 ) );
TEST_EQUAL( 0, mbedtls_ecp_point_write_binary(
&grp, &R, MBEDTLS_ECP_PF_UNCOMPRESSED,
&len, actual_result, sizeof( actual_result ) ) );
ASSERT_COMPARE( expected_result->x, expected_result->len,
actual_result, len );
exit:
mbedtls_ecp_group_free( &grp );
mbedtls_ecp_point_free( &P1 );
mbedtls_ecp_point_free( &P2 );
mbedtls_ecp_point_free( &R );
mbedtls_mpi_free( &u1 );
mbedtls_mpi_free( &u2 );
}
/* END_CASE */
/* BEGIN_CASE */
void ecp_fast_mod( int id, char * N_str )
{
@ -1152,6 +1207,36 @@ exit:
}
/* END_CASE */
/* BEGIN_CASE depends_on:HAVE_FIX_NEGATIVE */
void fix_negative( data_t *N_bin, int c, int bits )
{
mbedtls_mpi C, M, N;
mbedtls_mpi_init( &C );
mbedtls_mpi_init( &M );
mbedtls_mpi_init( &N );
/* C = - c * 2^bits (positive since c is negative) */
TEST_EQUAL( 0, mbedtls_mpi_lset( &C, -c ) );
TEST_EQUAL( 0, mbedtls_mpi_shift_l( &C, bits ) );
TEST_EQUAL( 0, mbedtls_mpi_read_binary( &N, N_bin->x, N_bin->len ) );
TEST_EQUAL( 0, mbedtls_mpi_grow( &N, C.n ) );
/* M = N - C = - ( C - N ) (expected result of fix_negative) */
TEST_EQUAL( 0, mbedtls_mpi_sub_mpi( &M, &N, &C ) );
mbedtls_ecp_fix_negative( &N, c, bits );
TEST_EQUAL( 0, mbedtls_mpi_cmp_mpi( &N, &M ) );
exit:
mbedtls_mpi_free( &C );
mbedtls_mpi_free( &M );
mbedtls_mpi_free( &N );
}
/* END_CASE */
/* BEGIN_CASE depends_on:MBEDTLS_SELF_TEST */
void ecp_selftest( )
{

View file

@ -10,21 +10,39 @@ mpi_null:
Base test mpi_read_write_string #1
mpi_read_write_string:10:"128":10:"128":100:0:0
Base test mpi_read_write_string #1 (Leading 0)
mpi_read_write_string:10:"0128":10:"128":100:0:0
Base test mpi_read_write_string #2
mpi_read_write_string:10:"128":16:"80":100:0:0
Base test mpi_read_write_string #3 (Read zero)
Base test mpi_read_write_string #3 (Read zero decimal)
mpi_read_write_string:10:"0":10:"0":100:0:0
Base test mpi_read_write_string #3 (Negative decimal) [#1]
Base test mpi_read_write_string #3 (Read zero hex)
mpi_read_write_string:16:"0":16:"00":100:0:0
Base test mpi_read_write_string #3 (Read minus zero decimal)
mpi_read_write_string:10:"-0":10:"0":100:0:0
Base test mpi_read_write_string #3 (Read minus zero hex)
mpi_read_write_string:16:"-0":16:"00":100:0:0
Base test mpi_read_write_string #3 (Negative decimal)
mpi_read_write_string:10:"-23":10:"-23":100:0:0
Base test mpi_read_write_string #3 (Negative hex)
Base test mpi_read_write_string #3 (Negative decimal, leading 0)
mpi_read_write_string:10:"-023":10:"-23":100:0:0
Base test mpi_read_write_string #3 (Negative hex -> decimal)
mpi_read_write_string:16:"-20":10:"-32":100:0:0
Base test mpi_read_write_string #3 (Negative decimal) [#2]
Base test mpi_read_write_string #3 (Negative hex)
mpi_read_write_string:16:"-23":16:"-23":100:0:0
Base test mpi_read_write_string #3 (Negative hex, leading 0)
mpi_read_write_string:16:"-023":16:"-23":100:0:0
Base test mpi_read_write_string #4 (Buffer just fits)
mpi_read_write_string:16:"-4":4:"-10":4:0:0
@ -49,12 +67,18 @@ mpi_read_write_string:10:"29":15:"1e":100:0:0
Test mpi_read_write_string #7
mpi_read_write_string:10:"56125680981752282334141896320372489490613963693556392520816017892111350604111697682705498319512049040516698827829292076808006940873974979584527073481012636016353913462376755556720019831187364993587901952757307830896531678727717924":16:"0941379d00fed1491fe15df284dfde4a142f68aa8d412023195cee66883e6290ffe703f4ea5963bf212713cee46b107c09182b5edcd955adac418bf4918e2889af48e1099d513830cec85c26ac1e158b52620e33ba8692f893efbb2f958b4424":200:0:0
Test mpi_read_write_string #8 (Empty MPI -> hex)
Test mpi_read_write_string #8 (Empty MPI hex -> hex)
mpi_read_write_string:16:"":16:"00":4:0:0
Test mpi_read_write_string #9 (Empty MPI -> dec)
Test mpi_read_write_string #9 (Empty MPI hex -> dec)
mpi_read_write_string:16:"":10:"0":4:0:0
Test mpi_read_write_string #8 (Empty MPI dec -> hex)
mpi_read_write_string:10:"":16:"00":4:0:0
Test mpi_read_write_string #9 (Empty MPI dec -> dec)
mpi_read_write_string:10:"":10:"0":4:0:0
Test mpi_write_string #10 (Negative hex with odd number of digits)
mpi_read_write_string:16:"-1":16:"":3:0:MBEDTLS_ERR_MPI_BUFFER_TOO_SMALL

View file

@ -250,6 +250,7 @@
<ClInclude Include="..\..\tests\include\test\drivers\test_driver.h" />
<ClInclude Include="..\..\library\check_crypto_config.h" />
<ClInclude Include="..\..\library\common.h" />
<ClInclude Include="..\..\library\ecp_invasive.h" />
<ClInclude Include="..\..\library\mps_common.h" />
<ClInclude Include="..\..\library\mps_error.h" />
<ClInclude Include="..\..\library\mps_reader.h" />