From 7fa11b88f3d223edca5bf3169b8b2fe93b498210 Mon Sep 17 00:00:00 2001 From: Janos Follath Date: Mon, 21 Nov 2022 14:48:02 +0000 Subject: [PATCH] mpi_exp_mod: rename local variables Signed-off-by: Janos Follath --- library/bignum.c | 54 +++++++++++++++++++++++++----------------------- 1 file changed, 28 insertions(+), 26 deletions(-) diff --git a/library/bignum.c b/library/bignum.c index a564edf6c..b611c3110 100644 --- a/library/bignum.c +++ b/library/bignum.c @@ -1970,12 +1970,12 @@ int mbedtls_mpi_exp_mod( mbedtls_mpi *X, const mbedtls_mpi *A, mbedtls_mpi *prec_RR ) { 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 bufsize, nbits; mbedtls_mpi_uint ei, mm, state; 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; 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 ); - wsize = ( i > 671 ) ? 6 : ( i > 239 ) ? 5 : + window_bitsize = ( i > 671 ) ? 6 : ( i > 239 ) ? 5 : ( i > 79 ) ? 4 : ( i > 23 ) ? 3 : 1; #if( MBEDTLS_MPI_WINDOW_SIZE < 6 ) - if( wsize > MBEDTLS_MPI_WINDOW_SIZE ) - wsize = MBEDTLS_MPI_WINDOW_SIZE; + if( window_bitsize > MBEDTLS_MPI_WINDOW_SIZE ) + window_bitsize = MBEDTLS_MPI_WINDOW_SIZE; #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 * 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_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 ) ); 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_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 ); /* * 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_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; bufsize = 0; nbits = 0; - wbits = 0; + size_t exponent_bits_in_window = 0; state = 0; 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] */ - 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 ); continue; } @@ -2157,28 +2157,29 @@ int mbedtls_mpi_exp_mod( mbedtls_mpi *X, const mbedtls_mpi *A, state = 2; 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 ); } /* - * 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 ); state--; 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++ ) { - 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 ); - 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 ); } } @@ -2217,7 +2218,8 @@ int mbedtls_mpi_exp_mod( mbedtls_mpi *X, const mbedtls_mpi *A, 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[1] );