Add skeleton ecdsa.[ch]
diff --git a/library/CMakeLists.txt b/library/CMakeLists.txt
index 28bbedc..6bc46e0 100644
--- a/library/CMakeLists.txt
+++ b/library/CMakeLists.txt
@@ -18,6 +18,7 @@
      dhm.c
      ecp.c
      ecdh.c
+     ecdsa.c
      entropy.c
      entropy_poll.c
      error.c