#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
* 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;
- * }
- *
+ * 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);
+ * unsigned int lt = constant_time_lt(a, b);
+ * c = constant_time_select(lt, a, b);
*/
/*
* 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.
- */
+/* 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.
- */
+/* 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.
- */
+/* 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.
- */
+/* 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_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));
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));
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 (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
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