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authorWojtek Kosior <wk@koszkonutek-tmp.pl.eu.org>2021-04-30 00:33:56 +0200
committerWojtek Kosior <wk@koszkonutek-tmp.pl.eu.org>2021-04-30 00:33:56 +0200
commitaa4d426b4d3527d7e166df1a05058c9a4a0f6683 (patch)
tree4ff17ce8b89a2321b9d0ed4bcfc37c447bcb6820 /openssl-1.1.0h/include/internal/constant_time_locl.h
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Diffstat (limited to 'openssl-1.1.0h/include/internal/constant_time_locl.h')
-rw-r--r--openssl-1.1.0h/include/internal/constant_time_locl.h185
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diff --git a/openssl-1.1.0h/include/internal/constant_time_locl.h b/openssl-1.1.0h/include/internal/constant_time_locl.h
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+/*
+ * 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 <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);
+
+/*
+ * 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);
+
+/*
+ * 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 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 unsigned int constant_time_lt(unsigned int a,
+ unsigned int b)
+{
+ return constant_time_msb(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 unsigned int constant_time_ge(unsigned int a,
+ unsigned int b)
+{
+ return ~constant_time_lt(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 int constant_time_is_zero(unsigned int a)
+{
+ return constant_time_msb(~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 unsigned char constant_time_eq_8(unsigned int a,
+ unsigned int b)
+{
+ return (unsigned char)(constant_time_eq(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 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)));
+}
+
+#ifdef __cplusplus
+}
+#endif
+
+#endif /* HEADER_CONSTANT_TIME_LOCL_H */