diff options
Diffstat (limited to 'openssl/crypto/constant_time_locl.h')
| -rw-r--r-- | openssl/crypto/constant_time_locl.h | 131 |
1 files changed, 63 insertions, 68 deletions
diff --git a/openssl/crypto/constant_time_locl.h b/openssl/crypto/constant_time_locl.h index c0483939f..c786aea94 100644 --- a/openssl/crypto/constant_time_locl.h +++ b/openssl/crypto/constant_time_locl.h @@ -1,5 +1,5 @@ /* crypto/constant_time_locl.h */ -/* +/*- * Utilities for constant-time cryptography. * * Author: Emilia Kasper (emilia@openssl.org) @@ -45,15 +45,15 @@ */ #ifndef HEADER_CONSTANT_TIME_LOCL_H -#define HEADER_CONSTANT_TIME_LOCL_H +# define HEADER_CONSTANT_TIME_LOCL_H -#include "e_os.h" /* For 'inline' */ +# include "e_os.h" /* For 'inline' */ #ifdef __cplusplus extern "C" { #endif -/* +/*- * The boolean methods return a bitmask of all ones (0xff...f) for true * and 0 for false. This is useful for choosing a value based on the result * of a conditional in constant time. For example, @@ -83,14 +83,16 @@ static inline unsigned int constant_time_msb(unsigned int a); */ static inline unsigned int constant_time_lt(unsigned int a, unsigned int b); /* Convenience method for getting an 8-bit mask. */ -static inline unsigned char constant_time_lt_8(unsigned int a, unsigned int b); +static inline unsigned char constant_time_lt_8(unsigned int a, + unsigned int b); /* * Returns 0xff..f if a >= b and 0 otherwise. */ static inline unsigned int constant_time_ge(unsigned int a, unsigned int b); /* Convenience method for getting an 8-bit mask. */ -static inline unsigned char constant_time_ge_8(unsigned int a, unsigned int b); +static inline unsigned char constant_time_ge_8(unsigned int a, + unsigned int b); /* * Returns 0xff..f if a == 0 and 0 otherwise. @@ -99,20 +101,19 @@ static inline unsigned int constant_time_is_zero(unsigned int a); /* Convenience method for getting an 8-bit mask. */ static inline unsigned char constant_time_is_zero_8(unsigned int a); - /* * Returns 0xff..f if a == b and 0 otherwise. */ static inline unsigned int constant_time_eq(unsigned int a, unsigned int b); /* Convenience method for getting an 8-bit mask. */ -static inline unsigned char constant_time_eq_8(unsigned int a, unsigned int b); +static inline unsigned char constant_time_eq_8(unsigned int a, + unsigned int b); /* Signed integers. */ static inline unsigned int constant_time_eq_int(int a, int b); /* Convenience method for getting an 8-bit mask. */ static inline unsigned char constant_time_eq_int_8(int a, int b); - -/* +/*- * Returns (mask & a) | (~mask & b). * * When |mask| is all 1s or all 0s (as returned by the methods above), @@ -120,97 +121,91 @@ static inline unsigned char constant_time_eq_int_8(int a, int b); * (if |mask| is zero). */ static inline unsigned int constant_time_select(unsigned int mask, - unsigned int a, unsigned int b); + unsigned int a, + unsigned int b); /* Convenience method for unsigned chars. */ static inline unsigned char constant_time_select_8(unsigned char mask, - unsigned char a, unsigned char b); + unsigned char a, + unsigned char b); /* Convenience method for signed integers. */ static inline int constant_time_select_int(unsigned int mask, int a, int b); static inline unsigned int constant_time_msb(unsigned int a) - { - return (unsigned int)((int)(a) >> (sizeof(int) * 8 - 1)); - } +{ + return 0 - (a >> (sizeof(a) * 8 - 1)); +} static inline unsigned int constant_time_lt(unsigned int a, unsigned int b) - { - unsigned int lt; - /* Case 1: msb(a) == msb(b). a < b iff the MSB of a - b is set.*/ - lt = ~(a ^ b) & (a - b); - /* Case 2: msb(a) != msb(b). a < b iff the MSB of b is set. */ - lt |= ~a & b; - return constant_time_msb(lt); - } +{ + return constant_time_msb(a ^ ((a ^ b) | ((a - b) ^ b))); +} static inline unsigned char constant_time_lt_8(unsigned int a, unsigned int b) - { - return (unsigned char)(constant_time_lt(a, b)); - } +{ + return (unsigned char)(constant_time_lt(a, b)); +} static inline unsigned int constant_time_ge(unsigned int a, unsigned int b) - { - unsigned int ge; - /* Case 1: msb(a) == msb(b). a >= b iff the MSB of a - b is not set.*/ - ge = ~((a ^ b) | (a - b)); - /* Case 2: msb(a) != msb(b). a >= b iff the MSB of a is set. */ - ge |= a & ~b; - return constant_time_msb(ge); - } +{ + return ~constant_time_lt(a, b); +} static inline unsigned char constant_time_ge_8(unsigned int a, unsigned int b) - { - return (unsigned char)(constant_time_ge(a, b)); - } +{ + return (unsigned char)(constant_time_ge(a, b)); +} static inline unsigned int constant_time_is_zero(unsigned int a) - { - return constant_time_msb(~a & (a - 1)); - } +{ + return constant_time_msb(~a & (a - 1)); +} static inline unsigned char constant_time_is_zero_8(unsigned int a) - { - return (unsigned char)(constant_time_is_zero(a)); - } +{ + return (unsigned char)(constant_time_is_zero(a)); +} static inline unsigned int constant_time_eq(unsigned int a, unsigned int b) - { - return constant_time_is_zero(a ^ b); - } +{ + return constant_time_is_zero(a ^ b); +} static inline unsigned char constant_time_eq_8(unsigned int a, unsigned int b) - { - return (unsigned char)(constant_time_eq(a, b)); - } +{ + return (unsigned char)(constant_time_eq(a, b)); +} static inline unsigned int constant_time_eq_int(int a, int b) - { - return constant_time_eq((unsigned)(a), (unsigned)(b)); - } +{ + return constant_time_eq((unsigned)(a), (unsigned)(b)); +} static inline unsigned char constant_time_eq_int_8(int a, int b) - { - return constant_time_eq_8((unsigned)(a), (unsigned)(b)); - } +{ + return constant_time_eq_8((unsigned)(a), (unsigned)(b)); +} static inline unsigned int constant_time_select(unsigned int mask, - unsigned int a, unsigned int b) - { - return (mask & a) | (~mask & b); - } + unsigned int a, + unsigned int b) +{ + return (mask & a) | (~mask & b); +} static inline unsigned char constant_time_select_8(unsigned char mask, - unsigned char a, unsigned char b) - { - return (unsigned char)(constant_time_select(mask, a, b)); - } + unsigned char a, + unsigned char b) +{ + return (unsigned char)(constant_time_select(mask, a, b)); +} -inline int constant_time_select_int(unsigned int mask, int a, int b) - { - return (int)(constant_time_select(mask, (unsigned)(a), (unsigned)(b))); - } +static inline int constant_time_select_int(unsigned int mask, int a, int b) +{ + return (int)(constant_time_select(mask, (unsigned)(a), (unsigned)(b))); +} #ifdef __cplusplus } #endif -#endif /* HEADER_CONSTANT_TIME_LOCL_H */ +#endif /* HEADER_CONSTANT_TIME_LOCL_H */ |