diff --git a/tests/data_files/rsa521.key b/tests/data_files/rsa521.key
new file mode 100644
index 0000000..0b940aa
--- /dev/null
+++ b/tests/data_files/rsa521.key
@@ -0,0 +1,9 @@
+-----BEGIN RSA PRIVATE KEY-----
+MIIBPQIBAAJCATG2mGDzy5v4XqNY/fK9KZDxt3qA1qT9+BekPdiWvffdJq+KwCN/
+Um4NM7EFyXH9vU/6ns6Z/EafMez0Kej1YsHDAgMBAAECQCdoYjwdMSHp4kksL5Aa
+0kDc58ni0chy9IgXo+FHjTVmR9DkaZANrwfVvYMJxqYCZo0im1Dw7ZJBUDJQNXnl
+ZokCIRiSk66I24AWa7XGUFvatVwXWi2ACE4QEKqzWQe1mQ24/wIhDHD1TCKpqucA
+XDI+1N7EHs+fN4CfTSWe8FPGiK6q3VM9AiESrKKLi/q011U4KeS8SfR2blDcL2cg
+XFkuQWqxzzLoGOUCIQmgl5E0+Ypwe0zc7NYZFDarf4+ZjqxKQnXCvk0irMHcGQIh
+EVPli6RQb3Gcx7vXJHltzSTno7NElzBDRMBVUlBmVxAJ
+-----END RSA PRIVATE KEY-----