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Manuel Pégourié-Gonnard 2013-11-21 18:33:36 +01:00
parent 469a209334
commit 36daa13d76
1 changed files with 9 additions and 6 deletions
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15
library/ecp.c
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@ -1449,13 +1449,16 @@ int ecp_mul( ecp_group *grp, ecp_point *R,
/*
* Sanity checks (before we even initialize anything)
*/
if( mpi_cmp_int( &P->Z, 1 ) != 0 )
return( POLARSSL_ERR_ECP_BAD_INPUT_DATA );
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 &&
/* We'll need this later, but do it now to possibly avoid checking P */
p_eq_g = ( 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 );
@ -1466,7 +1469,7 @@ int ecp_mul( ecp_group *grp, ecp_point *R,
/*
* Minimize the number of multiplications, that is minimize
* 10 * d * w + 18 * 2^(w-1) + 11 * d + 7 * w
* 10 * d * w + 18 * 2^(w-1) + 11 * d + 7 * w, with d = ceil( nbits / w )
* (see costs of the various parts, with 1S = 1M)
*/
w = grp->nbits >= 384 ? 5 : 4;
@ -1479,12 +1482,12 @@ int ecp_mul( ecp_group *grp, ecp_point *R,
w++;
/*
* Make sure w is within limits.
* Make sure w is within bounds.
* (The last test is useful only for very small curves in the test suite.)
*/
if( w > POLARSSL_ECP_WINDOW_SIZE )
w = POLARSSL_ECP_WINDOW_SIZE;
if( w < 2 || w >= grp->nbits )
if( w >= grp->nbits )
w = 2;
/* Other sizes that depend on w */