1. COMP101 – Exploring Multimedia and Internet Computing LA2 (Thu 14:00 – 16:50) TA: Jackie Lo

2. Lecture Review  Email Header (e.g. sender information, Date, etc.) are supplied by the system (but could be faked). Privacy on e-mails  “ hops ” (servers and routers) between mail sender and recipient can read and store the IP packet send through them  there is no trace for tampering

3. Lecture Review  Email Privacy ObjectivesWho ’ s Action? Whose Key? Key Type Encrypt dataSenderReceiverPublic key Sign dataSender Private key Verify signatureReceiverSenderPublic key Decrypt dataReceiver Private key

4. Lecture Review  Using PKI at HKUST E-cert, we got last lab  Exchange the public keys  Safeguard your private key  Email abuse Questions? My FYP is about tailor-made spam email filter. If you are interested, you can come and find the details in my office.

5. Lecture Review  World Wide Web (WWW) Browser  Tool for browsing the web, e.g. IE, Netscape Uniform Resource Locator (URL)  Address of webpage Hyper Text Markup Language (HTML)  Common Language (Code) presenting webpage Hyper Text Transfer Protocol (HTTP)  Protocol for transfer webpage

6. Lecture Review  Cookies small files placed by Web server in a directory of the user ’ s computer to track users ’ browsing habits.  Security using the web Use secure connection (https) before entering personal data. (A golden lock at the bottom of the browser)secure connection

7. Reminders  Test 1 will be on 28 Feb. (Wed) In class:  10 – 11 am  LTA In the evening:  7 – 8 pm  Room 2306 (via Lift 17-18)  Please revise ALL the course materials. Lecture Slides Lab Notes and Assignment Lecture Notes (Please at least read once!)

8. Lab 3  Follow the steps in lab 3 Notes for using excel function  =VLOOKUP(Lookup_value, Table_array, Col_index_num)  =IF(condition, return_if_true, return_if_false)  =COUNT(range)  =COUNTIF(range,criteria)