207 lines
7.4 KiB
C
Executable file
207 lines
7.4 KiB
C
Executable file
/* crypto/constant_time_locl.h */
|
|
/*-
|
|
* Utilities for constant-time cryptography.
|
|
*
|
|
* Author: Emilia Kasper (emilia@openssl.org)
|
|
* Based on previous work by Bodo Moeller, Emilia Kasper, Adam Langley
|
|
* (Google).
|
|
* ====================================================================
|
|
* Copyright (c) 2014 The OpenSSL Project. All rights reserved.
|
|
*
|
|
* Redistribution and use in source and binary forms, with or without
|
|
* modification, are permitted provided that the following conditions
|
|
* are met:
|
|
* 1. Redistributions of source code must retain the copyright
|
|
* notice, this list of conditions and the following disclaimer.
|
|
* 2. Redistributions in binary form must reproduce the above copyright
|
|
* notice, this list of conditions and the following disclaimer in the
|
|
* documentation and/or other materials provided with the distribution.
|
|
* 3. All advertising materials mentioning features or use of this software
|
|
* must display the following acknowledgement:
|
|
* "This product includes cryptographic software written by
|
|
* Eric Young (eay@cryptsoft.com)"
|
|
* The word 'cryptographic' can be left out if the rouines from the library
|
|
* being used are not cryptographic related :-).
|
|
* 4. If you include any Windows specific code (or a derivative thereof) from
|
|
* the apps directory (application code) you must include an acknowledgement:
|
|
* "This product includes software written by Tim Hudson (tjh@cryptsoft.com)"
|
|
*
|
|
* THIS SOFTWARE IS PROVIDED BY ERIC YOUNG ``AS IS'' AND
|
|
* ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
|
|
* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
|
|
* ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
|
|
* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
|
|
* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
|
|
* OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
|
|
* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
|
|
* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
|
|
* OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
|
|
* SUCH DAMAGE.
|
|
*
|
|
* The licence and distribution terms for any publically available version or
|
|
* derivative of this code cannot be changed. i.e. this code cannot simply be
|
|
* copied and put under another distribution licence
|
|
* [including the GNU Public Licence.]
|
|
*/
|
|
|
|
#ifndef HEADER_CONSTANT_TIME_LOCL_H
|
|
# define HEADER_CONSTANT_TIME_LOCL_H
|
|
|
|
__BEGIN_HIDDEN_DECLS
|
|
|
|
/*-
|
|
* 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,
|
|
*
|
|
* if (a < b) {
|
|
* c = a;
|
|
* } else {
|
|
* c = b;
|
|
* }
|
|
*
|
|
* can be written as
|
|
*
|
|
* unsigned int lt = constant_time_lt(a, b);
|
|
* c = constant_time_select(lt, a, b);
|
|
*/
|
|
|
|
/*
|
|
* Returns the given value with the MSB copied to all the other
|
|
* bits. Uses the fact that arithmetic shift shifts-in the sign bit.
|
|
* However, this is not ensured by the C standard so you may need to
|
|
* replace this with something else on odd CPUs.
|
|
*/
|
|
static inline unsigned int constant_time_msb(unsigned int a);
|
|
|
|
/*
|
|
* Returns 0xff..f if a < b and 0 otherwise.
|
|
*/
|
|
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);
|
|
|
|
/*
|
|
* 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);
|
|
|
|
/*
|
|
* Returns 0xff..f if a == 0 and 0 otherwise.
|
|
*/
|
|
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);
|
|
/* 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),
|
|
* the select methods return either |a| (if |mask| is nonzero) or |b|
|
|
* (if |mask| is zero).
|
|
*/
|
|
static inline unsigned int constant_time_select(unsigned int mask,
|
|
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);
|
|
/* 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 0 - (a >> (sizeof(a) * 8 - 1));
|
|
}
|
|
|
|
static inline unsigned int constant_time_lt(unsigned int a, unsigned int b)
|
|
{
|
|
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));
|
|
}
|
|
|
|
static inline unsigned int constant_time_ge(unsigned int a, unsigned int b)
|
|
{
|
|
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));
|
|
}
|
|
|
|
static inline unsigned int constant_time_is_zero(unsigned int a)
|
|
{
|
|
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));
|
|
}
|
|
|
|
static inline unsigned int constant_time_eq(unsigned int a, unsigned int 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));
|
|
}
|
|
|
|
static inline unsigned int constant_time_eq_int(int a, int 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));
|
|
}
|
|
|
|
static inline unsigned int constant_time_select(unsigned int mask,
|
|
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));
|
|
}
|
|
|
|
static inline int constant_time_select_int(unsigned int mask, int a, int b)
|
|
{
|
|
return (int)(constant_time_select(mask, (unsigned)(a), (unsigned)(b)));
|
|
}
|
|
|
|
void err_clear_last_constant_time(int clear);
|
|
|
|
__END_HIDDEN_DECLS
|
|
|
|
#endif /* HEADER_CONSTANT_TIME_LOCL_H */
|