1 files changed, 18 insertions, 0 deletions
diff --git a/slides/2019-side-channels/img/countermeasure.py b/slides/2019-side-channels/img/countermeasure.py
new file mode 100755
index 0000000..dda0868
--- /dev/null
+++ b/slides/2019-side-channels/img/countermeasure.py
@@ -0,0 +1,18 @@
+#!/usr/bin/python
+
+def is_equal(s1, s2):
+    '''
+    Returns true if the strings s1 and s2 encode the same information.
+    '''
+    if len(s1) != len(s2):
+        return False
+
+    result = 0
+    for (x,y) in zip(s1,s2):
+        result |= ord(x) ^ ord(y)
+
+    return result == 0
+
+target, strs = "abc", [ "ab", "abc", "abcd", "bbc", "abe" ]
+for s in strs:
+    print("{} == {} ? {}".format(target,s,is_equal(target,s)))