Network Security The Parts of the Sum Stephen T. Walker Overview by Justin Childs

Intro Problem - The whole is greater than the sum Three Parts –Encryption –Protocols –Trusted Computer System Principles True Security requires all the parts

What is a Network Don’t Care –Components are important –Their characteristics –System boundaries –“Definition” may be obsolete, inaccurate, limited

Network Security Elements Encryption –Open channels –System Security - limited usefulness –Secrecy of implementation Network Protocols –Standards, secret protocols impair adoption –Security parameters, levels Trusted System Principles –measures that satisfy a security policy

Relationship Between Elements Link Level Encryption Problem - Encrypts everything –At what level do you know what must be encrypted? Trusted Systems isolate secure portions of system –Network level fig. 5 –Transport level fig. 6 Combine encryption with trusted host computer? –Exposure –Allows application level encryption –Isolate but allow control by host TCB

Security Services and Mechanisms Fig. 7 Need to assure performance as well, not just mechanisms used Two misconceptions –TSCEC lacks list of services & mechanisms –adding S & M without level of assurance for each

Example of Problems in Network Security PC Encryption Services - fig. 8 –Encrypt data as it leaves PC –untrusted computer –Trusted systems - fig 10, 11 Ideal System –utilize trusted system - fig 12 –Peripheral encryption –Header & encrypted data combined in PC

Secure Data Network System Issues Protocol extensions –at internet & transport layers –integrate encryption & key mng. Fig 12 –Problem - Transport mechanism above Encryption level –Why not SP4 above transport layer? Requires trusted computer system that’s not available - Fig. 14 –Level of trust not specified.