Defensics X.509 Test Suite is a security assessment test tool for analysing the security and robustness of X.509 implementations. The X.509 Test Suite used the Defensics robustness testing methodology to locate flaws in X.509 Certificate implementations. The test materials are capable of finding and identifying various different kinds of flaws with varying levels of severity. This is accomplished by feeding the tested implementation with various carefully crafted malformed X.509 Certificates. The test suite implements only those parts of the X.509 specification that are required to create certificate files that can be used for testing.