IEC 62351-3:2014+A1:2018 specifies how to provide confidentiality, integrity protection, and message level authentication for SCADA and telecontrol protocols that make use of TCP/IP as a message transport layer when cyber-security is required. Although there are many possible solutions to secure TCP/IP, the particular scope of this part is to provide security between communicating entities at either end of a TCP/IP connection within the end communicating entities. This part of IEC 62351 reflects the security requirements of the IEC power systems management protocols. This consolidated version consists of the first edition (2014) and its amendment 1 (2018). Therefore, no need to order amendment in addition to this publication.