This course introduces the basics of cyber defense starting with foundational models such as Bell-LaPadula and information flow frameworks. These underlying policy enforcements mechanisms help introduce basic functional protections, starting with authentication methods. Learners will be introduced to a series of different authentication solutions and protocols, including RSA SecureID and Kerberos, in the context of a canonical schema.   The basics of cryptography are also introduced with attention to conventional block ciphers as well as public key cryptography. Important cryptographic techniques such as cipher block chaining and triple-DES are explained. Modern certification authority-based cryptographic support is also discussed and shown to provide basis for secure e-commerce using Secure Sockets Layer (SSL) schemes.