handshake: added support for ECDH with curve X25519

This follows draft-ietf-tls-rfc4492bis-07 and rfc7748

1 files changed, 15 insertions, 0 deletions

diff --git a/lib/mem.c b/lib/mem.c
index 2f4fc93f34..65f06588a3 100644
--- a/lib/mem.c
+++ b/lib/mem.c
@@ -113,3 +113,18 @@ void gnutls_free(void *ptr)
 }
 
 #endif
+
+/* Returns 1 if the provided buffer is all zero.
+ * It leaks no information via timing.
+ */
+unsigned _gnutls_mem_is_zero(const uint8_t *ptr, unsigned size)
+{
+	unsigned i;
+	uint8_t res = 0;
+
+	for (i=0;i<size;i++) {
+		res |= ptr[i];
+	}
+
+	return ((res==0)?1:0);
+}