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Group related code together

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This will be split to a new function next.
This commit is contained in:
Manuel Pégourié-Gonnard 2017-03-09 12:23:45 +01:00
parent 510d5caece
commit 7306dff01f
1 changed files with 10 additions and 10 deletions
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20
library/ecp.c
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@ -1389,7 +1389,7 @@ static int ecp_mul_comb( mbedtls_ecp_group *grp, mbedtls_ecp_point *R,
unsigned char w, m_is_odd, p_eq_g, pre_len, i;
size_t d;
unsigned char k[COMB_MAX_D + 1];
mbedtls_ecp_point *T;
mbedtls_ecp_point *T = NULL;
mbedtls_mpi M, mm;
#if defined(MBEDTLS_ECP_EARLY_RETURN)
@ -1404,6 +1404,15 @@ static int ecp_mul_comb( mbedtls_ecp_group *grp, mbedtls_ecp_point *R,
if( mbedtls_mpi_get_bit( &grp->N, 0 ) != 1 )
return( MBEDTLS_ERR_ECP_BAD_INPUT_DATA );
/*
* Make sure M is odd (M = m or M = N - m, since N is odd)
* using the fact that m * P = - (N - m) * P
*/
m_is_odd = ( mbedtls_mpi_get_bit( m, 0 ) == 1 );
MBEDTLS_MPI_CHK( mbedtls_mpi_copy( &M, m ) );
MBEDTLS_MPI_CHK( mbedtls_mpi_sub_mpi( &mm, &grp->N, m ) );
MBEDTLS_MPI_CHK( mbedtls_mpi_safe_cond_assign( &M, &mm, ! m_is_odd ) );
/*
* Minimize the number of multiplications, that is minimize
* 10 * d * w + 18 * 2^(w-1) + 11 * d + 7 * w, with d = ceil( nbits / w )
@ -1462,15 +1471,6 @@ static int ecp_mul_comb( mbedtls_ecp_group *grp, mbedtls_ecp_point *R,
}
}
/*
* Make sure M is odd (M = m or M = N - m, since N is odd)
* using the fact that m * P = - (N - m) * P
*/
m_is_odd = ( mbedtls_mpi_get_bit( m, 0 ) == 1 );
MBEDTLS_MPI_CHK( mbedtls_mpi_copy( &M, m ) );
MBEDTLS_MPI_CHK( mbedtls_mpi_sub_mpi( &mm, &grp->N, m ) );
MBEDTLS_MPI_CHK( mbedtls_mpi_safe_cond_assign( &M, &mm, ! m_is_odd ) );
/*
* Go for comb multiplication, R = M * P
*/