diff options
Diffstat (limited to 'library/bignum.c')
| -rw-r--r-- | library/bignum.c | 22 |
1 files changed, 16 insertions, 6 deletions
diff --git a/library/bignum.c b/library/bignum.c index d3a150c..d27c130 100644 --- a/library/bignum.c +++ b/library/bignum.c @@ -63,6 +63,11 @@ static void mbedtls_mpi_zeroize( mbedtls_mpi_uint *v, size_t n ) { volatile mbedtls_mpi_uint *p = v; while( n-- ) *p++ = 0; } +/* Implementation that should never be optimized out by the compiler */ +static void mbedtls_zeroize( void *v, size_t n ) { + volatile unsigned char *p = v; while( n-- ) *p++ = 0; +} + #define ciL (sizeof(mbedtls_mpi_uint)) /* chars in limb */ #define biL (ciL << 3) /* bits in limb */ #define biH (ciL << 2) /* half limb size */ @@ -672,16 +677,20 @@ cleanup: int mbedtls_mpi_read_binary( mbedtls_mpi *X, const unsigned char *buf, size_t buflen ) { int ret; - size_t i, j, n; + size_t i, j; + size_t const limbs = CHARS_TO_LIMBS( buflen ); - for( n = 0; n < buflen; n++ ) - if( buf[n] != 0 ) - break; + /* Ensure that target MPI has exactly the necessary number of limbs */ + if( X->n != limbs ) + { + mbedtls_mpi_free( X ); + mbedtls_mpi_init( X ); + MBEDTLS_MPI_CHK( mbedtls_mpi_grow( X, limbs ) ); + } - MBEDTLS_MPI_CHK( mbedtls_mpi_grow( X, CHARS_TO_LIMBS( buflen - n ) ) ); MBEDTLS_MPI_CHK( mbedtls_mpi_lset( X, 0 ) ); - for( i = buflen, j = 0; i > n; i--, j++ ) + for( i = buflen, j = 0; i > 0; i--, j++ ) X->p[j / ciL] |= ((mbedtls_mpi_uint) buf[i - 1]) << ((j % ciL) << 3); cleanup: @@ -1882,6 +1891,7 @@ int mbedtls_mpi_fill_random( mbedtls_mpi *X, size_t size, MBEDTLS_MPI_CHK( mbedtls_mpi_read_binary( X, buf, size ) ); cleanup: + mbedtls_zeroize( buf, sizeof( buf ) ); return( ret ); } |