+++ /dev/null
-/* 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
-
-#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,
- *
- * 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 (unsigned int)((int)(a) >> (sizeof(int) * 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);
- }
-
-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)
- {
- 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);
- }
-
-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));
- }
-
-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 */
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