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bignum_mod: Updated modulus lifecycle with mm and rr.

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This patch updates the `mbedtls_mpi_mod_modulus_setup/free()`
methods to precalculate mm and rr(Montgomery const squared) during
setup and zeroize it during free.

A static `set_mont_const_square()` is added to manage the memory allocation
and parameter checking before invoking the
`mbedtls_mpi_core_get_mont_r2_unsafe()`

Signed-off-by: Minos Galanakis <minos.galanakis@arm.com>
This commit is contained in:
Minos Galanakis 2022-10-11 11:28:24 +01:00
parent 760f5d6b6b
commit 8b33363315
1 changed files with 38 additions and 2 deletions
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40
library/bignum_mod.c
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@ -77,6 +77,9 @@ void mbedtls_mpi_mod_modulus_free( mbedtls_mpi_mod_modulus *m )
switch( m->int_rep )
{
case MBEDTLS_MPI_MOD_REP_MONTGOMERY:
mbedtls_platform_zeroize( (mbedtls_mpi_uint *) m->rep.mont.rr,
m->limbs );
mbedtls_free( (mbedtls_mpi_uint *)m->rep.mont.rr );
m->rep.mont.rr = NULL;
m->rep.mont.mm = 0; break;
case MBEDTLS_MPI_MOD_REP_OPT_RED:
@ -93,6 +96,38 @@ void mbedtls_mpi_mod_modulus_free( mbedtls_mpi_mod_modulus *m )
m->int_rep = MBEDTLS_MPI_MOD_REP_INVALID;
}
static int set_mont_const_square( const mbedtls_mpi_uint **X,
const mbedtls_mpi_uint *A,
size_t limbs )
{
int ret = MBEDTLS_ERR_ERROR_CORRUPTION_DETECTED;
mbedtls_mpi N;
mbedtls_mpi RR;
mbedtls_mpi_init( &N );
mbedtls_mpi_init( &RR );
if ( A == NULL || limbs == 0 || limbs >= ( MBEDTLS_MPI_MAX_LIMBS / 2 ) - 2 )
goto cleanup;
if ( !mbedtls_mpi_grow( &N, limbs ))
memcpy( N.p, A, sizeof(mbedtls_mpi_uint) * limbs );
else
goto cleanup;
mbedtls_mpi_core_get_mont_r2_unsafe(&RR, &N);
*X = RR.p;
RR.p = NULL;
ret = 0;
cleanup:
mbedtls_mpi_free(&N);
mbedtls_mpi_free(&RR);
ret = ( ret != 0 ) ? MBEDTLS_ERR_ERROR_CORRUPTION_DETECTED : 0;
return( ret );
}
int mbedtls_mpi_mod_modulus_setup( mbedtls_mpi_mod_modulus *m,
const mbedtls_mpi_uint *p,
size_t p_limbs,
@ -120,8 +155,9 @@ int mbedtls_mpi_mod_modulus_setup( mbedtls_mpi_mod_modulus *m,
{
case MBEDTLS_MPI_MOD_REP_MONTGOMERY:
m->int_rep = int_rep;
m->rep.mont.rr = NULL;
m->rep.mont.mm = 0; break;
m->rep.mont.mm = mbedtls_mpi_core_montmul_init( m->p );
set_mont_const_square( &m->rep.mont.rr, m->p, m->limbs );
break;
case MBEDTLS_MPI_MOD_REP_OPT_RED:
m->int_rep = int_rep;
m->rep.ored = NULL;