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Change ecp_mul() prototype to allow randomization

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(Also improve an error code while at it.)
This commit is contained in:
Manuel Pégourié-Gonnard
2013-09-02 14:29:09 +02:00
parent f451bac000
commit e09d2f8261
10 changed files with 99 additions and 37 deletions
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20
library/ecp.c
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@ -1166,7 +1166,8 @@ cleanup:
* random m in the range 0 .. 2^nbits - 1.
*/
int ecp_mul( const ecp_group *grp, ecp_point *R,
const mpi *m, const ecp_point *P )
const mpi *m, const ecp_point *P,
int (*f_rng)(void *, unsigned char *, size_t), void *p_rng )
{
int ret;
unsigned char w, m_is_odd;
@ -1175,18 +1176,21 @@ int ecp_mul( const ecp_group *grp, ecp_point *R,
ecp_point Q, T[ MAX_PRE_LEN ];
mpi M;
((void) f_rng);
((void) p_rng);
if( mpi_cmp_int( m, 0 ) < 0 || mpi_msb( m ) > grp->nbits )
return( POLARSSL_ERR_ECP_GENERIC );
return( POLARSSL_ERR_ECP_BAD_INPUT_DATA );
w = grp->nbits >= 521 ? 6 :
grp->nbits >= 224 ? 5 :
4;
4;
/*
* Make sure w is within the limits.
* The last test ensures that none of the precomputed points is zero,
* which wouldn't be handled correctly by ecp_normalize_many().
* It is only useful for small curves, as used in the test suite.
* It is only useful for very small curves, as used in the test suite.
*/
if( w > POLARSSL_ECP_WINDOW_SIZE )
w = POLARSSL_ECP_WINDOW_SIZE;
@ -1348,7 +1352,7 @@ int ecp_gen_keypair( const ecp_group *grp, mpi *d, ecp_point *Q,
}
while( mpi_cmp_int( d, 1 ) < 0 );
return( ecp_mul( grp, Q, d, &grp->G ) );
return( ecp_mul( grp, Q, d, &grp->G, f_rng, p_rng ) );
}
#if defined(POLARSSL_SELF_TEST)
@ -1402,12 +1406,12 @@ int ecp_self_test( int verbose )
#endif /* POLARSSL_ECP_DP_SECP192R1_ENABLED */
if( verbose != 0 )
printf( " ECP test #1 (SPA resistance): " );
printf( " ECP test #1 (resistance to simple timing attacks): " );
add_count = 0;
dbl_count = 0;
MPI_CHK( mpi_read_string( &m, 16, exponents[0] ) );
MPI_CHK( ecp_mul( &grp, &R, &m, &grp.G ) );
MPI_CHK( ecp_mul( &grp, &R, &m, &grp.G, NULL, NULL ) );
for( i = 1; i < sizeof( exponents ) / sizeof( exponents[0] ); i++ )
{
@ -1417,7 +1421,7 @@ int ecp_self_test( int verbose )
dbl_count = 0;
MPI_CHK( mpi_read_string( &m, 16, exponents[i] ) );
MPI_CHK( ecp_mul( &grp, &R, &m, &grp.G ) );
MPI_CHK( ecp_mul( &grp, &R, &m, &grp.G, NULL, NULL ) );
if( add_count != add_c_prev || dbl_count != dbl_c_prev )
{