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-rw-r--r--NorthstarDLL/include/internal/constant_time.h842
1 files changed, 421 insertions, 421 deletions
diff --git a/NorthstarDLL/include/internal/constant_time.h b/NorthstarDLL/include/internal/constant_time.h
index 0ed6f823..c4d6df5c 100644
--- a/NorthstarDLL/include/internal/constant_time.h
+++ b/NorthstarDLL/include/internal/constant_time.h
@@ -1,421 +1,421 @@
-/*
- * 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 */
+/*
+ * 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 */
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