This course is based on the principles of communication and communication network, enabling students to understand the relevant theories and developments in the field of cryptography, network and communication security, and to master the principles and technologies related to network and communication security.This course introduces the basic concepts of network and communication security, symmetric cryptosystem (traditional cryptography, data encryption standard, advanced encryption standard, block cipher mode, stream cipher), public key cryptosystem (RSA, elliptic curve code),Cryptographic data integrity algorithms (cryptographic hash functions, message authentication codes, digital signatures), mutual trust (key management and distribution, user authentication), network security and system security instances (wireless network security, email security, intruders), firewalls) and legal and ethical issues in network and communication security.