This paper is devoted to e-healthcare security systems based on modern security mechanisms and Public Key Infrastructure (PKI) systems. We signified that only general and multi-layered security infrastructure could cope with possible attacks to e-healthcare systems. We evaluated security mechanisms on application, transport and network layers of ISO/OSI reference model. These mechanisms include confidentiality protection based on symmetrical cryptographic algorithms and digital signature technology based on asymmetrical algorithms for authentication, integrity protection and non-repudiation. User strong authentication procedures based on smart cards, digital certificates and PKI systems are especially emphasized. We gave a brief description of smart cards, HSMs and main components of the PKI systems, emphasizing Certification Authority and its role in establishing cryptographically unique identities of the valid system users based on X.509 digital certificates. Emerging e-healthcare systems and possible appropriate security mechanisms based on proposed Generic CA model are analyzed.