diff --git a/library/constant_time.c b/library/constant_time.c index a786d380b..093ae2872 100644 --- a/library/constant_time.c +++ b/library/constant_time.c @@ -253,19 +253,7 @@ unsigned mbedtls_ct_size_bool_eq(size_t x, #if defined(MBEDTLS_PKCS1_V15) && defined(MBEDTLS_RSA_C) && !defined(MBEDTLS_RSA_ALT) -/** Constant-flow "greater than" comparison: - * return x > y - * - * This is equivalent to \p x > \p y, but is likely to be compiled - * to code using bitwise operation rather than a branch. - * - * \param x The first value to analyze. - * \param y The second value to analyze. - * - * \return 1 if \p x greater than \p y, otherwise 0. - */ -static unsigned mbedtls_ct_size_gt(size_t x, - size_t y) +unsigned mbedtls_ct_size_gt(size_t x, size_t y) { /* Return the sign bit (1 for negative) of (y - x). */ return (y - x) >> (sizeof(size_t) * 8 - 1); @@ -345,23 +333,7 @@ void mbedtls_ct_mpi_uint_cond_assign(size_t n, #if defined(MBEDTLS_PKCS1_V15) && defined(MBEDTLS_RSA_C) && !defined(MBEDTLS_RSA_ALT) -/** Shift some data towards the left inside a buffer. - * - * `mbedtls_ct_mem_move_to_left(start, total, offset)` is functionally - * equivalent to - * ``` - * memmove(start, start + offset, total - offset); - * memset(start + offset, 0, total - offset); - * ``` - * but it strives to use a memory access pattern (and thus total timing) - * that does not depend on \p offset. This timing independence comes at - * the expense of performance. - * - * \param start Pointer to the start of the buffer. - * \param total Total size of the buffer. - * \param offset Offset from which to copy \p total - \p offset bytes. - */ -static void mbedtls_ct_mem_move_to_left(void *start, +void mbedtls_ct_mem_move_to_left(void *start, size_t total, size_t offset) { diff --git a/library/constant_time_internal.h b/library/constant_time_internal.h index d8a0fc7b3..84ca96233 100644 --- a/library/constant_time_internal.h +++ b/library/constant_time_internal.h @@ -300,4 +300,42 @@ static inline unsigned char mbedtls_ct_uchar_in_range_if(unsigned char low, #endif /* MBEDTLS_BASE64_C */ + +#if defined(MBEDTLS_PKCS1_V15) && defined(MBEDTLS_RSA_C) && !defined(MBEDTLS_RSA_ALT) + +/** Constant-flow "greater than" comparison: + * return x > y + * + * This is equivalent to \p x > \p y, but is likely to be compiled + * to code using bitwise operation rather than a branch. + * + * \param x The first value to analyze. + * \param y The second value to analyze. + * + * \return 1 if \p x greater than \p y, otherwise 0. + */ +unsigned mbedtls_ct_size_gt(size_t x, size_t y); + +/** Shift some data towards the left inside a buffer. + * + * `mbedtls_ct_mem_move_to_left(start, total, offset)` is functionally + * equivalent to + * ``` + * memmove(start, start + offset, total - offset); + * memset(start + offset, 0, total - offset); + * ``` + * but it strives to use a memory access pattern (and thus total timing) + * that does not depend on \p offset. This timing independence comes at + * the expense of performance. + * + * \param start Pointer to the start of the buffer. + * \param total Total size of the buffer. + * \param offset Offset from which to copy \p total - \p offset bytes. + */ +void mbedtls_ct_mem_move_to_left(void *start, + size_t total, + size_t offset); + +#endif /* defined(MBEDTLS_PKCS1_V15) && defined(MBEDTLS_RSA_C) && !defined(MBEDTLS_RSA_ALT) */ + #endif /* MBEDTLS_CONSTANT_TIME_INTERNAL_H */