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Diffstat (limited to 'include/internal/constant_time.h')
| -rw-r--r-- | include/internal/constant_time.h | 421 |
1 files changed, 0 insertions, 421 deletions
diff --git a/include/internal/constant_time.h b/include/internal/constant_time.h deleted file mode 100644 index 0ed6f823..00000000 --- a/include/internal/constant_time.h +++ /dev/null @@ -1,421 +0,0 @@ -/* - * Copyright 2014-2021 The OpenSSL Project Authors. All Rights Reserved. - * - * Licensed under the Apache License 2.0 (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 OSSL_INTERNAL_CONSTANT_TIME_H -# define OSSL_INTERNAL_CONSTANT_TIME_H -# pragma once - -# include <stdlib.h> -# include <string.h> -# include <openssl/e_os2.h> /* For 'ossl_inline' */ - -/*- - * 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. */ -static ossl_inline unsigned int constant_time_msb(unsigned int a); -/* Convenience method for uint32_t. */ -static ossl_inline uint32_t constant_time_msb_32(uint32_t 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); -/* Convenience method for getting a 32-bit mask. */ -static ossl_inline uint32_t constant_time_is_zero_32(uint32_t 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 uint32_t. */ -static ossl_inline uint32_t constant_time_select_32(uint32_t mask, uint32_t a, - uint32_t 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 uint32_t constant_time_msb_32(uint32_t a) -{ - return 0 - (a >> 31); -} - -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 uint32_t constant_time_is_zero_32(uint32_t a) -{ - return constant_time_msb_32(~a & (a - 1)); -} - -static ossl_inline uint64_t constant_time_is_zero_64(uint64_t a) -{ - return constant_time_msb_64(~a & (a - 1)); -} - -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)); -} - -/* - * Returns the value unmodified, but avoids optimizations. - * The barriers prevent the compiler from narrowing down the - * possible value range of the mask and ~mask in the select - * statements, which avoids the recognition of the select - * and turning it into a conditional load or branch. - */ -static ossl_inline unsigned int value_barrier(unsigned int a) -{ -#if !defined(OPENSSL_NO_ASM) && defined(__GNUC__) - unsigned int r; - __asm__("" : "=r"(r) : "0"(a)); -#else - volatile unsigned int r = a; -#endif - return r; -} - -/* Convenience method for uint32_t. */ -static ossl_inline uint32_t value_barrier_32(uint32_t a) -{ -#if !defined(OPENSSL_NO_ASM) && defined(__GNUC__) - uint32_t r; - __asm__("" : "=r"(r) : "0"(a)); -#else - volatile uint32_t r = a; -#endif - return r; -} - -/* Convenience method for uint64_t. */ -static ossl_inline uint64_t value_barrier_64(uint64_t a) -{ -#if !defined(OPENSSL_NO_ASM) && defined(__GNUC__) - uint64_t r; - __asm__("" : "=r"(r) : "0"(a)); -#else - volatile uint64_t r = a; -#endif - return r; -} - -/* Convenience method for size_t. */ -static ossl_inline size_t value_barrier_s(size_t a) -{ -#if !defined(OPENSSL_NO_ASM) && defined(__GNUC__) - size_t r; - __asm__("" : "=r"(r) : "0"(a)); -#else - volatile size_t r = a; -#endif - return r; -} - -static ossl_inline unsigned int constant_time_select(unsigned int mask, - unsigned int a, - unsigned int b) -{ - return (value_barrier(mask) & a) | (value_barrier(~mask) & b); -} - -static ossl_inline size_t constant_time_select_s(size_t mask, - size_t a, - size_t b) -{ - return (value_barrier_s(mask) & a) | (value_barrier_s(~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 uint32_t constant_time_select_32(uint32_t mask, uint32_t a, - uint32_t b) -{ - return (value_barrier_32(mask) & a) | (value_barrier_32(~mask) & b); -} - -static ossl_inline uint64_t constant_time_select_64(uint64_t mask, uint64_t a, - uint64_t b) -{ - return (value_barrier_64(mask) & a) | (value_barrier_64(~mask) & b); -} - -/* - * mask must be 0xFFFFFFFF or 0x00000000. - * - * if (mask) { - * uint32_t tmp = *a; - * - * *a = *b; - * *b = tmp; - * } - */ -static ossl_inline void constant_time_cond_swap_32(uint32_t mask, uint32_t *a, - uint32_t *b) -{ - uint32_t xor = *a ^ *b; - - xor &= mask; - *a ^= xor; - *b ^= xor; -} - -/* - * mask must be 0xFFFFFFFF or 0x00000000. - * - * if (mask) { - * uint64_t tmp = *a; - * - * *a = *b; - * *b = tmp; - * } - */ -static ossl_inline void constant_time_cond_swap_64(uint64_t mask, uint64_t *a, - uint64_t *b) -{ - uint64_t xor = *a ^ *b; - - xor &= mask; - *a ^= xor; - *b ^= xor; -} - -/* - * mask must be 0xFF or 0x00. - * "constant time" is per len. - * - * if (mask) { - * unsigned char tmp[len]; - * - * memcpy(tmp, a, len); - * memcpy(a, b); - * memcpy(b, tmp); - * } - */ -static ossl_inline void constant_time_cond_swap_buff(unsigned char mask, - unsigned char *a, - unsigned char *b, - size_t len) -{ - size_t i; - unsigned char tmp; - - for (i = 0; i < len; i++) { - tmp = a[i] ^ b[i]; - tmp &= mask; - a[i] ^= tmp; - b[i] ^= tmp; - } -} - -/* - * table is a two dimensional array of bytes. Each row has rowsize elements. - * Copies row number idx into out. rowsize and numrows are not considered - * private. - */ -static ossl_inline void constant_time_lookup(void *out, - const void *table, - size_t rowsize, - size_t numrows, - size_t idx) -{ - size_t i, j; - const unsigned char *tablec = (const unsigned char *)table; - unsigned char *outc = (unsigned char *)out; - unsigned char mask; - - memset(out, 0, rowsize); - - /* Note idx may underflow - but that is well defined */ - for (i = 0; i < numrows; i++, idx--) { - mask = (unsigned char)constant_time_is_zero_s(idx); - for (j = 0; j < rowsize; j++) - *(outc + j) |= constant_time_select_8(mask, *(tablec++), 0); - } -} - -/* - * Expected usage pattern is to unconditionally set error and then - * wipe it if there was no actual error. |clear| is 1 or 0. - */ -void err_clear_last_constant_time(int clear); - -#endif /* OSSL_INTERNAL_CONSTANT_TIME_H */ |