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Local readability improvements

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Signed-off-by: Gilles Peskine <Gilles.Peskine@arm.com>
This commit is contained in:
Gilles Peskine 2022-11-16 20:26:14 +01:00 committed by Janos Follath
parent 0de0a049f1
commit d83b5cb504
1 changed files with 18 additions and 16 deletions
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34
library/bignum_core.c
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@ -605,23 +605,23 @@ static void exp_mod_precompute_window( const mbedtls_mpi_uint *A,
mbedtls_mpi_uint *Wtable,
mbedtls_mpi_uint *temp )
{
/* pointers to table entries */
mbedtls_mpi_uint *Wcur, *Wlast, *W1;
/* W[0] = 1 (in Montgomery presentation) */
memset( Wtable, 0, AN_limbs * ciL );
Wtable[0] = 1;
mbedtls_mpi_core_montmul( Wtable, Wtable, RR, AN_limbs, N, AN_limbs, mm, temp );
Wcur = Wtable + AN_limbs;
/* W[1] = A * R^2 * R^-1 mod N = A * R mod N */
memcpy( Wcur, A, AN_limbs * ciL );
mbedtls_mpi_core_montmul( Wcur, Wcur, RR, AN_limbs, N, AN_limbs, mm, temp );
W1 = Wcur;
Wcur += AN_limbs;
mbedtls_mpi_uint *W1 = Wtable + AN_limbs;
mbedtls_mpi_core_montmul( W1, A, RR, AN_limbs, N, AN_limbs, mm, temp );
/* W[i+1] = W[i] * W[1], i >= 2 */
Wlast = W1;
for( size_t i = 2; i < welem; i++, Wlast += AN_limbs, Wcur += AN_limbs )
mbedtls_mpi_core_montmul( Wcur, Wlast, W1, AN_limbs, N, AN_limbs, mm, temp );
mbedtls_mpi_uint *Wprev = W1;
for( size_t i = 2; i < welem; i++ )
{
mbedtls_mpi_uint *Wcur = Wprev + AN_limbs;
mbedtls_mpi_core_montmul( Wcur, Wprev, W1, AN_limbs, N, AN_limbs, mm, temp );
Wprev = Wcur;
}
}
int mbedtls_mpi_core_exp_mod( mbedtls_mpi_uint *X,
@ -702,15 +702,17 @@ int mbedtls_mpi_core_exp_mod( mbedtls_mpi_uint *X,
mbedtls_mpi_core_ct_uint_table_lookup( Wselect, Wtable,
AN_limbs, welem, window );
mbedtls_mpi_core_montmul( X, X, Wselect, AN_limbs, N, AN_limbs, mm, temp );
window = window_bits = 0;
window = 0;
window_bits = 0;
continue;
}
/* Load next exponent limb if necessary */
if( limb_bits_remaining == 0 )
{
cur_limb = *--E;
E_limbs--;
--E;
cur_limb = *E;
--E_limbs;
limb_bits_remaining = biL;
}
@ -721,8 +723,8 @@ int mbedtls_mpi_core_exp_mod( mbedtls_mpi_uint *X,
window <<= 1;
window |= ( cur_limb >> ( biL - 1 ) );
cur_limb <<= 1;
window_bits++;
limb_bits_remaining--;
++window_bits;
--limb_bits_remaining;
}
/* Convert X back to normal presentation */