9018f3ce0f
Standardize comments. Reviewed-by: Andy Polyakov <appro@openssl.org> (Merged from https://github.com/openssl/openssl/pull/3727)
247 lines
8.2 KiB
C
247 lines
8.2 KiB
C
/*
|
|
* Copyright 2014-2016 The OpenSSL Project Authors. All Rights Reserved.
|
|
*
|
|
* Licensed under the OpenSSL license (the "License"). You may not use
|
|
* this file except in compliance with the License. You can obtain a copy
|
|
* in the file LICENSE in the source distribution or at
|
|
* https://www.openssl.org/source/license.html
|
|
*/
|
|
|
|
#ifndef HEADER_CONSTANT_TIME_LOCL_H
|
|
# define HEADER_CONSTANT_TIME_LOCL_H
|
|
|
|
# include <stdlib.h>
|
|
# include <openssl/e_os2.h> /* For 'ossl_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 ossl_inline unsigned int constant_time_msb(unsigned int a);
|
|
/* Convenience method for uint64_t. */
|
|
static ossl_inline uint64_t constant_time_msb_64(uint64_t a);
|
|
|
|
/* Returns 0xff..f if a < b and 0 otherwise. */
|
|
static ossl_inline unsigned int constant_time_lt(unsigned int a,
|
|
unsigned int b);
|
|
/* Convenience method for getting an 8-bit mask. */
|
|
static ossl_inline unsigned char constant_time_lt_8(unsigned int a,
|
|
unsigned int b);
|
|
/* Convenience method for uint64_t. */
|
|
static ossl_inline uint64_t constant_time_lt_64(uint64_t a, uint64_t b);
|
|
|
|
/* Returns 0xff..f if a >= b and 0 otherwise. */
|
|
static ossl_inline unsigned int constant_time_ge(unsigned int a,
|
|
unsigned int b);
|
|
/* Convenience method for getting an 8-bit mask. */
|
|
static ossl_inline unsigned char constant_time_ge_8(unsigned int a,
|
|
unsigned int b);
|
|
|
|
/* Returns 0xff..f if a == 0 and 0 otherwise. */
|
|
static ossl_inline unsigned int constant_time_is_zero(unsigned int a);
|
|
/* Convenience method for getting an 8-bit mask. */
|
|
static ossl_inline unsigned char constant_time_is_zero_8(unsigned int a);
|
|
|
|
/* Returns 0xff..f if a == b and 0 otherwise. */
|
|
static ossl_inline unsigned int constant_time_eq(unsigned int a,
|
|
unsigned int b);
|
|
/* Convenience method for getting an 8-bit mask. */
|
|
static ossl_inline unsigned char constant_time_eq_8(unsigned int a,
|
|
unsigned int b);
|
|
/* Signed integers. */
|
|
static ossl_inline unsigned int constant_time_eq_int(int a, int b);
|
|
/* Convenience method for getting an 8-bit mask. */
|
|
static ossl_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 ossl_inline unsigned int constant_time_select(unsigned int mask,
|
|
unsigned int a,
|
|
unsigned int b);
|
|
/* Convenience method for unsigned chars. */
|
|
static ossl_inline unsigned char constant_time_select_8(unsigned char mask,
|
|
unsigned char a,
|
|
unsigned char b);
|
|
/* Convenience method for uint64_t. */
|
|
static ossl_inline uint64_t constant_time_select_64(uint64_t mask, uint64_t a,
|
|
uint64_t b);
|
|
/* Convenience method for signed integers. */
|
|
static ossl_inline int constant_time_select_int(unsigned int mask, int a,
|
|
int b);
|
|
|
|
|
|
static ossl_inline unsigned int constant_time_msb(unsigned int a)
|
|
{
|
|
return 0 - (a >> (sizeof(a) * 8 - 1));
|
|
}
|
|
|
|
static ossl_inline uint64_t constant_time_msb_64(uint64_t a)
|
|
{
|
|
return 0 - (a >> 63);
|
|
}
|
|
|
|
static ossl_inline size_t constant_time_msb_s(size_t a)
|
|
{
|
|
return 0 - (a >> (sizeof(a) * 8 - 1));
|
|
}
|
|
|
|
static ossl_inline unsigned int constant_time_lt(unsigned int a,
|
|
unsigned int b)
|
|
{
|
|
return constant_time_msb(a ^ ((a ^ b) | ((a - b) ^ b)));
|
|
}
|
|
|
|
static ossl_inline size_t constant_time_lt_s(size_t a, size_t b)
|
|
{
|
|
return constant_time_msb_s(a ^ ((a ^ b) | ((a - b) ^ b)));
|
|
}
|
|
|
|
static ossl_inline unsigned char constant_time_lt_8(unsigned int a,
|
|
unsigned int b)
|
|
{
|
|
return (unsigned char)(constant_time_lt(a, b));
|
|
}
|
|
|
|
static ossl_inline uint64_t constant_time_lt_64(uint64_t a, uint64_t b)
|
|
{
|
|
return constant_time_msb_64(a ^ ((a ^ b) | ((a - b) ^ b)));
|
|
}
|
|
|
|
static ossl_inline unsigned int constant_time_ge(unsigned int a,
|
|
unsigned int b)
|
|
{
|
|
return ~constant_time_lt(a, b);
|
|
}
|
|
|
|
static ossl_inline size_t constant_time_ge_s(size_t a, size_t b)
|
|
{
|
|
return ~constant_time_lt_s(a, b);
|
|
}
|
|
|
|
static ossl_inline unsigned char constant_time_ge_8(unsigned int a,
|
|
unsigned int b)
|
|
{
|
|
return (unsigned char)(constant_time_ge(a, b));
|
|
}
|
|
|
|
static ossl_inline unsigned char constant_time_ge_8_s(size_t a, size_t b)
|
|
{
|
|
return (unsigned char)(constant_time_ge_s(a, b));
|
|
}
|
|
|
|
static ossl_inline unsigned int constant_time_is_zero(unsigned int a)
|
|
{
|
|
return constant_time_msb(~a & (a - 1));
|
|
}
|
|
|
|
static ossl_inline size_t constant_time_is_zero_s(size_t a)
|
|
{
|
|
return constant_time_msb_s(~a & (a - 1));
|
|
}
|
|
|
|
static ossl_inline unsigned char constant_time_is_zero_8(unsigned int a)
|
|
{
|
|
return (unsigned char)(constant_time_is_zero(a));
|
|
}
|
|
|
|
static ossl_inline unsigned int constant_time_eq(unsigned int a,
|
|
unsigned int b)
|
|
{
|
|
return constant_time_is_zero(a ^ b);
|
|
}
|
|
|
|
static ossl_inline size_t constant_time_eq_s(size_t a, size_t b)
|
|
{
|
|
return constant_time_is_zero_s(a ^ b);
|
|
}
|
|
|
|
static ossl_inline unsigned char constant_time_eq_8(unsigned int a,
|
|
unsigned int b)
|
|
{
|
|
return (unsigned char)(constant_time_eq(a, b));
|
|
}
|
|
|
|
static ossl_inline unsigned char constant_time_eq_8_s(size_t a, size_t b)
|
|
{
|
|
return (unsigned char)(constant_time_eq_s(a, b));
|
|
}
|
|
|
|
static ossl_inline unsigned int constant_time_eq_int(int a, int b)
|
|
{
|
|
return constant_time_eq((unsigned)(a), (unsigned)(b));
|
|
}
|
|
|
|
static ossl_inline unsigned char constant_time_eq_int_8(int a, int b)
|
|
{
|
|
return constant_time_eq_8((unsigned)(a), (unsigned)(b));
|
|
}
|
|
|
|
static ossl_inline unsigned int constant_time_select(unsigned int mask,
|
|
unsigned int a,
|
|
unsigned int b)
|
|
{
|
|
return (mask & a) | (~mask & b);
|
|
}
|
|
|
|
static ossl_inline size_t constant_time_select_s(size_t mask,
|
|
size_t a,
|
|
size_t b)
|
|
{
|
|
return (mask & a) | (~mask & b);
|
|
}
|
|
|
|
static ossl_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 ossl_inline int constant_time_select_int(unsigned int mask, int a,
|
|
int b)
|
|
{
|
|
return (int)(constant_time_select(mask, (unsigned)(a), (unsigned)(b)));
|
|
}
|
|
|
|
static ossl_inline int constant_time_select_int_s(size_t mask, int a, int b)
|
|
{
|
|
return (int)(constant_time_select((unsigned)mask, (unsigned)(a),
|
|
(unsigned)(b)));
|
|
}
|
|
|
|
static ossl_inline uint64_t constant_time_select_64(uint64_t mask, uint64_t a,
|
|
uint64_t b)
|
|
{
|
|
return (mask & a) | (~mask & b);
|
|
}
|
|
|
|
#ifdef __cplusplus
|
|
}
|
|
#endif
|
|
|
|
#endif /* HEADER_CONSTANT_TIME_LOCL_H */
|