Real-World Problems of PKI Hierarchy

Public key cryptography has become very popular recently. To use it securely, it is necessary to employ systems offering at least a basic set of functions associated with public key cryptosystems containing generation of keys, secure generation of certificates, verification of signatures, dissemination of revoked certificates, and so on. This paper demonstrates that the use of public key cryptography is not easy and it is very difficult to perform the above-mentioned actions in a way satisfying some predefined security level. The reason is in the complexity of the problem. We are not generally able to ensure the usage of systems able to work with all existing algorithms, key lengths, and formats in the whole public key infrastructure. Also, some people are of the opinion that X.509 as a basis for PKI is obsolete.