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Tighten ecp_mul() validity checks

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This commit is contained in:
Manuel Pégourié-Gonnard 2013-11-21 09:28:03 +01:00
parent 09ceaf49d0
commit ff27b7c968
4 changed files with 42 additions and 43 deletions
library
ecp.c

30
library/ecp.c
View file

@ -1440,21 +1440,24 @@ int ecp_mul( ecp_group *grp, ecp_point *R,
ecp_point Q, *T = NULL, S[2];
mpi M;
if( mpi_cmp_int( m, 0 ) < 0 || mpi_msb( m ) > grp->nbits )
return( POLARSSL_ERR_ECP_BAD_INPUT_DATA );
/*
* Sanity checks (before we even initialize anything)
*/
if( ( ret = ecp_check_privkey( grp, m ) ) != 0 )
return( ret );
/* We'll need this later, but do it now to possibly avoid cheking P */
p_eq_g = ( mpi_cmp_int( &P->Z, 1 ) == 0 &&
mpi_cmp_mpi( &P->Y, &grp->G.Y ) == 0 &&
mpi_cmp_mpi( &P->X, &grp->G.X ) == 0 );
if( ! p_eq_g && ( ret = ecp_check_pubkey( grp, P ) ) != 0 )
return( ret );
mpi_init( &M );
ecp_point_init( &Q );
ecp_point_init( &S[0] );
ecp_point_init( &S[1] );
/*
* Check if P == G
*/
p_eq_g = ( mpi_cmp_int( &P->Z, 1 ) == 0 &&
mpi_cmp_mpi( &P->Y, &grp->G.Y ) == 0 &&
mpi_cmp_mpi( &P->X, &grp->G.X ) == 0 );
/*
* Minimize the number of multiplications, that is minimize
* 10 * d * w + 18 * 2^(w-1) + 11 * d + 7 * w
@ -2061,13 +2064,12 @@ int ecp_self_test( int verbose )
/* exponents especially adapted for secp192r1 */
const char *exponents[] =
{
"000000000000000000000000000000000000000000000000", /* zero */
"000000000000000000000000000000000000000000000001", /* one */
"FFFFFFFFFFFFFFFFFFFFFFFF99DEF836146BC9B1B4D22831", /* N */
"FFFFFFFFFFFFFFFFFFFFFFFF99DEF836146BC9B1B4D22830", /* N - 1 */
"5EA6F389A38B8BC81E767753B15AA5569E1782E30ABE7D25", /* random */
"400000000000000000000000000000000000000000000000",
"7FFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFF",
"555555555555555555555555555555555555555555555555",
"400000000000000000000000000000000000000000000000", /* one and zeros */
"7FFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFF", /* all ones */
"555555555555555555555555555555555555555555555555", /* 101010... */
};
ecp_group_init( &grp );