1. 1 91.413 Data Communications I & 91.561 Computer Security I Faculty currently includes: G. Chen, Costello, Elbirt, Liu, D. Martin, Wang

2. 2 91.413: Internet protocol stack  application: supporting network applications FTP, SMTP, STTP  transport: host-host data transfer TCP, UDP  network: routing of datagrams from source to destination IP, routing protocols  link: data transfer between neighboring network elements PPP, Ethernet application transport network link physical

3. 3 91.413: “Nuts and bolts” view  protocols control sending and receiving of msgs e.g., TCP, IP, HTTP, FTP, PPP  Internet: “ network of networks”  loosely hierarchical  public Internet vs. private intranet  Internet standards RFC:  Request for comments IETF:  Internet Engineering Task Force local ISP company network regional ISP router workstation server mobile

4. 4 91.561 Computer Security I  Threats Eavesdropping Impersonation Forgery Intrusion  Countermeasures Encryption Authentication Integrity protection Access control  Success of Internet means huge numbers of computers attached to it Can be attacked from afar Need to resist attackers

5. 5 91.561 Topics  Basic concepts of cryptography and network security  Modern symmetric-key encryption algorithms  Public-key cryptosystems  Key management  Authentication and digital signature  Methodology of writing secure code  Students will implement encryption and authentication algorithms as network applications  Industrial strength socket programming Current Project