utils: Add a constant time memeq() variant for cryptographic purposes

1 files changed, 19 insertions, 0 deletions

diff --git a/src/libstrongswan/utils/utils.c b/src/libstrongswan/utils/utils.c
index 02a720945..3d5e3dfc9 100644
--- a/src/libstrongswan/utils/utils.c
+++ b/src/libstrongswan/utils/utils.c
@@ -112,6 +112,25 @@ void memwipe_noinline(void *ptr, size_t n)
 /**
  * Described in header.
  */
+bool memeq_const(const void *x, const void *y, size_t len)
+{
+	const u_char *a, *b;
+	u_int bad = 0;
+	size_t i;
+
+	a = (const u_char*)x;
+	b = (const u_char*)y;
+
+	for (i = 0; i < len; i++)
+	{
+		bad |= a[i] != b[i];
+	}
+	return !bad;
+}
+
+/**
+ * Described in header.
+ */
 void *memstr(const void *haystack, const char *needle, size_t n)
 {
 	const u_char *pos = haystack;