This two-volume LNICST 567-568 set constitutes the post-conference proceedings of the 19th International Conference on Security and Privacy in Communication Networks, SecureComm 2023, held in October 2023 in Hong Kong, China.The 52 papers were carefully reviewed and selected from 180 submissions. The papers presented in these two volumes are clustered into various thematical issues as follows:  Part I: AI for Security; Authentication; Blockchain and Distributed System Security; Cryptography; Data Security.Part II: Intrusion and Anomaly Detection; IoT Security; Network Security; Privacy; Program Analysis; Software Security.