Add some util functions for timing attack countermeasures from Falko

1 files changed, 48 insertions, 0 deletions

diff --git a/src/lib/utils/ta_utils.h b/src/lib/utils/ta_utils.h
new file mode 100644
index 000000000..36ee551cc
--- /dev/null
+++ b/src/lib/utils/ta_utils.h
@@ -0,0 +1,48 @@
+/*
+* Timing Attack Countermeasure Functions
+* (C) 2010 Falko Strenzke, Jack Lloyd
+*
+* Distributed under the terms of the Botan license
+*/
+
+#ifndef BOTAN_TIMING_ATTACK_CM_H__
+#define BOTAN_TIMING_ATTACK_CM_H__
+
+#include <botan/types.h>
+
+namespace Botan {
+
+namespace TA_CM {
+
+/**
+* Function used in timing attack countermeasures
+* See Wagner, Molnar, et al "The Program Counter Security Model"
+*
+* @param in an integer
+* @return 0 if in == 0 else 0xFFFFFFFF
+*/
+u32bit gen_mask_u32bit(u32bit in);
+
+/**
+* Branch-free maximum
+* Note: assumes twos-complement signed representation
+* @param a an integer
+* @param b an integer
+* @return max(a,b)
+*/
+u32bit max_32(u32bit a, u32bit b);
+
+/**
+* Branch-free minimum
+* Note: assumes twos-complement signed representation
+* @param a an integer
+* @param b an integer
+* @return min(a,b)
+*/
+u32bit min_32(u32bit a, u32bit b);
+
+}
+
+}
+
+#endif