use pyasn1 for creating the dss-sig-value structure
diff --git a/setup.py b/setup.py
index c841911..4dd9e62 100644
--- a/setup.py
+++ b/setup.py
@@ -44,6 +44,7 @@
 # If you add a new dep here you probably need to add it in the tox.ini as well
 test_requirements = [
     "pytest",
+    "pyasn1",
     "pretend",
     "iso8601",
 ]