Analysis of theoretical security level of PDF Encryption mechanism based on X.509 certificates

PDF Encryption is a content security mechanism developed and used by Adobe in their products. In this paper, we have checked a theoretical security level of a variant that uses public key infrastructure and X.509 certificates. We have described a basis of this mechanism and we have performed a simple security analysis. Then, we have showed possible tweaks and security improvements. At the end, we have given some recommendations that can improve security of a content secured with PDF Encryption based on X.509 certificates.Keywords: DRM, cryptography, security level, PDF Encryption, Adobe, X.509