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mpi_exp_mod: rename local variables

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Signed-off-by: Janos Follath <janos.follath@arm.com>
This commit is contained in:
Janos Follath 2022-11-21 14:48:02 +00:00
parent 844614814e
commit 7fa11b88f3
1 changed files with 28 additions and 26 deletions
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54
library/bignum.c
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@ -1970,12 +1970,12 @@ int mbedtls_mpi_exp_mod( mbedtls_mpi *X, const mbedtls_mpi *A,
mbedtls_mpi *prec_RR ) mbedtls_mpi *prec_RR )
{ {
int ret = MBEDTLS_ERR_ERROR_CORRUPTION_DETECTED; int ret = MBEDTLS_ERR_ERROR_CORRUPTION_DETECTED;
size_t wbits, wsize, one = 1; size_t window_bitsize, one = 1;
size_t i, j, nblimbs; size_t i, j, nblimbs;
size_t bufsize, nbits; size_t bufsize, nbits;
mbedtls_mpi_uint ei, mm, state; mbedtls_mpi_uint ei, mm, state;
mbedtls_mpi RR, T, W[ ( 1 << MBEDTLS_MPI_WINDOW_SIZE ) + 1 ], WW, Apos; mbedtls_mpi RR, T, W[ ( 1 << MBEDTLS_MPI_WINDOW_SIZE ) + 1 ], WW, Apos;
const size_t w_count = sizeof( W ) / sizeof( W[0] ); const size_t w_table_size = sizeof( W ) / sizeof( W[0] );
int neg; int neg;
MPI_VALIDATE_RET( X != NULL ); MPI_VALIDATE_RET( X != NULL );
@ -2004,12 +2004,12 @@ int mbedtls_mpi_exp_mod( mbedtls_mpi *X, const mbedtls_mpi *A,
i = mbedtls_mpi_bitlen( E ); i = mbedtls_mpi_bitlen( E );
wsize = ( i > 671 ) ? 6 : ( i > 239 ) ? 5 : window_bitsize = ( i > 671 ) ? 6 : ( i > 239 ) ? 5 :
( i > 79 ) ? 4 : ( i > 23 ) ? 3 : 1; ( i > 79 ) ? 4 : ( i > 23 ) ? 3 : 1;
#if( MBEDTLS_MPI_WINDOW_SIZE < 6 ) #if( MBEDTLS_MPI_WINDOW_SIZE < 6 )
if( wsize > MBEDTLS_MPI_WINDOW_SIZE ) if( window_bitsize > MBEDTLS_MPI_WINDOW_SIZE )
wsize = MBEDTLS_MPI_WINDOW_SIZE; window_bitsize = MBEDTLS_MPI_WINDOW_SIZE;
#endif #endif
/* /*
@ -2024,7 +2024,7 @@ int mbedtls_mpi_exp_mod( mbedtls_mpi *X, const mbedtls_mpi *A,
* To achieve this, we make a copy of X and we use the table entry in each * To achieve this, we make a copy of X and we use the table entry in each
* calculation from this point on. * calculation from this point on.
*/ */
const size_t x_index = w_count - 1; const size_t x_index = w_table_size - 1;
mbedtls_mpi_init( &W[x_index] ); mbedtls_mpi_init( &W[x_index] );
mbedtls_mpi_copy( &W[x_index], X ); mbedtls_mpi_copy( &W[x_index], X );
@ -2088,23 +2088,23 @@ int mbedtls_mpi_exp_mod( mbedtls_mpi *X, const mbedtls_mpi *A,
MBEDTLS_MPI_CHK( mbedtls_mpi_copy( &W[x_index], &RR ) ); MBEDTLS_MPI_CHK( mbedtls_mpi_copy( &W[x_index], &RR ) );
mpi_montred( &W[x_index], N, mm, &T ); mpi_montred( &W[x_index], N, mm, &T );
if( wsize > 1 ) if( window_bitsize > 1 )
{ {
/* /*
* W[1 << (wsize - 1)] = W[1] ^ (wsize - 1) * W[1 << (window_bitsize - 1)] = W[1] ^ (window_bitsize - 1)
*/ */
j = one << ( wsize - 1 ); j = one << ( window_bitsize - 1 );
MBEDTLS_MPI_CHK( mbedtls_mpi_grow( &W[j], N->n + 1 ) ); MBEDTLS_MPI_CHK( mbedtls_mpi_grow( &W[j], N->n + 1 ) );
MBEDTLS_MPI_CHK( mbedtls_mpi_copy( &W[j], &W[1] ) ); MBEDTLS_MPI_CHK( mbedtls_mpi_copy( &W[j], &W[1] ) );
for( i = 0; i < wsize - 1; i++ ) for( i = 0; i < window_bitsize - 1; i++ )
mpi_montmul( &W[j], &W[j], N, mm, &T ); mpi_montmul( &W[j], &W[j], N, mm, &T );
/* /*
* W[i] = W[i - 1] * W[1] * W[i] = W[i - 1] * W[1]
*/ */
for( i = j + 1; i < ( one << wsize ); i++ ) for( i = j + 1; i < ( one << window_bitsize ); i++ )
{ {
MBEDTLS_MPI_CHK( mbedtls_mpi_grow( &W[i], N->n + 1 ) ); MBEDTLS_MPI_CHK( mbedtls_mpi_grow( &W[i], N->n + 1 ) );
MBEDTLS_MPI_CHK( mbedtls_mpi_copy( &W[i], &W[i - 1] ) ); MBEDTLS_MPI_CHK( mbedtls_mpi_copy( &W[i], &W[i - 1] ) );
@ -2116,7 +2116,7 @@ int mbedtls_mpi_exp_mod( mbedtls_mpi *X, const mbedtls_mpi *A,
nblimbs = E->n; nblimbs = E->n;
bufsize = 0; bufsize = 0;
nbits = 0; nbits = 0;
wbits = 0; size_t exponent_bits_in_window = 0;
state = 0; state = 0;
while( 1 ) while( 1 )
@ -2146,7 +2146,7 @@ int mbedtls_mpi_exp_mod( mbedtls_mpi *X, const mbedtls_mpi *A,
/* /*
* out of window, square W[x_index] * out of window, square W[x_index]
*/ */
MBEDTLS_MPI_CHK( mpi_select( &WW, W, w_count, x_index ) ); MBEDTLS_MPI_CHK( mpi_select( &WW, W, w_table_size, x_index ) );
mpi_montmul( &W[x_index], &WW, N, mm, &T ); mpi_montmul( &W[x_index], &WW, N, mm, &T );
continue; continue;
} }
@ -2157,28 +2157,29 @@ int mbedtls_mpi_exp_mod( mbedtls_mpi *X, const mbedtls_mpi *A,
state = 2; state = 2;
nbits++; nbits++;
wbits |= ( ei << ( wsize - nbits ) ); exponent_bits_in_window |= ( ei << ( window_bitsize - nbits ) );
if( nbits == wsize ) if( nbits == window_bitsize )
{ {
/* /*
* W[x_index] = W[x_index]^wsize R^-1 mod N * W[x_index] = W[x_index]^window_bitsize R^-1 mod N
*/ */
for( i = 0; i < wsize; i++ ) for( i = 0; i < window_bitsize; i++ )
{ {
MBEDTLS_MPI_CHK( mpi_select( &WW, W, w_count, x_index ) ); MBEDTLS_MPI_CHK( mpi_select( &WW, W, w_table_size, x_index ) );
mpi_montmul( &W[x_index], &WW, N, mm, &T ); mpi_montmul( &W[x_index], &WW, N, mm, &T );
} }
/* /*
* W[x_index] = W[x_index] * W[wbits] R^-1 mod N * W[x_index] = W[x_index] * W[exponent_bits_in_window] R^-1 mod N
*/ */
MBEDTLS_MPI_CHK( mpi_select( &WW, W, w_count, wbits ) ); MBEDTLS_MPI_CHK( mpi_select( &WW, W, w_table_size,
exponent_bits_in_window ) );
mpi_montmul( &W[x_index], &WW, N, mm, &T ); mpi_montmul( &W[x_index], &WW, N, mm, &T );
state--; state--;
nbits = 0; nbits = 0;
wbits = 0; exponent_bits_in_window = 0;
} }
} }
@ -2187,14 +2188,14 @@ int mbedtls_mpi_exp_mod( mbedtls_mpi *X, const mbedtls_mpi *A,
*/ */
for( i = 0; i < nbits; i++ ) for( i = 0; i < nbits; i++ )
{ {
MBEDTLS_MPI_CHK( mpi_select( &WW, W, w_count, x_index ) ); MBEDTLS_MPI_CHK( mpi_select( &WW, W, w_table_size, x_index ) );
mpi_montmul( &W[x_index], &WW, N, mm, &T ); mpi_montmul( &W[x_index], &WW, N, mm, &T );
wbits <<= 1; exponent_bits_in_window <<= 1;
if( ( wbits & ( one << wsize ) ) != 0 ) if( ( exponent_bits_in_window & ( one << window_bitsize ) ) != 0 )
{ {
MBEDTLS_MPI_CHK( mpi_select( &WW, W, w_count, 1 ) ); MBEDTLS_MPI_CHK( mpi_select( &WW, W, w_table_size, 1 ) );
mpi_montmul( &W[x_index], &WW, N, mm, &T ); mpi_montmul( &W[x_index], &WW, N, mm, &T );
} }
} }
@ -2217,7 +2218,8 @@ int mbedtls_mpi_exp_mod( mbedtls_mpi *X, const mbedtls_mpi *A,
cleanup: cleanup:
for( i = ( one << ( wsize - 1 ) ); i < ( one << wsize ); i++ ) for( i = ( one << ( window_bitsize - 1 ) );
i < ( one << window_bitsize ); i++ )
mbedtls_mpi_free( &W[i] ); mbedtls_mpi_free( &W[i] );
mbedtls_mpi_free( &W[1] ); mbedtls_mpi_free( &W[1] );