CSCI920 (Week 13) Revision (II) Guilin Wang SCSSE Nov. 2010

Contact Info Room: Consultation times (updated): - Mon.: 14-16pm - Wed.: 11-13pm URL:

 Revision Strategies  Exam Tips  P vs NP (One Grand Challenge in CS)  Privacy  Cloud Computing  Quantum Computing Outline

 Each lecture does cover a lot of topics  Try to grasp at least the 5 most important topics discussed in each lecture  Those may involve concepts, methods, mechanisms, models, (dis)advantages etc.  The majority exam questions come from those topics, as they are the main points. Revision Strategies

 30 marks for 10 short questions  10 marks for 1 long question  So, the exam accounts for 40% in your final subject mark.  When you answer a question: Understand the question first Focus your answer on the question Write your answer legible Exam Tips

 What is the P vs NP problem? Informally, this problem asks: For any problem, if a given solution can be efficiently verified can it also be efficiently solved by a computer? Quickly verify an answer  Quickly find the answer? P vs NP: One Grand Challenge in CS:

 A more formal definition -P and NP are two complexity classes of problems -P: All problems that can be solved on a deterministic sequential machine in polynomial time, measured by the size of its input. -NP: All problems whose positive solutions can be verified in polynomial time, or equivalently, whose solution can be found in polynomial time on a non- deterministic machine. -So, is P = NP? Source: Wiki P vs NP: One Grand Challenge in CS:

 NP Complete Problems  Examples of P, NP, NP Complete Problems  Why is P vs NP important?  Other challenges we mentioned in lectures are not examinable. P vs NP: One Grand Challenge in CS:

 What is privacy? A working definition give by Ruth Gavison: Privacy can be defined as the limitation of others’ access to an individual. It has three key elements: Secrecy, Anonymity, and Solitude.  Why is privacy important? Intrinsic good – It is desirable for its own sake. That is, it has value and is of benefit in and of itself. Instrumental good – It has value to support other benefits and rights: Privacy

 What are the implications of ICTs for privacy? Many ICTs threaten and erode privacy – particularly information privacy Information gathering – online & mobile Technologies Data matching, data merging, and data mining  How is privacy protected by the law? In Australia, there is no constitutional ‘right’ to privacy But a patchwork of laws exist to protect privacy Information privacy is now largely protected in Australia by federal and state laws. In particular, the Privacy Act 1988 (Cth), the Privacy Amendment (Private Sector) Act 2000 (Cth). Privacy

Cloud Computing  What is cloud computing? A working definition proposed by NIST5 It has 5 essential characteristics, 3 service models, and 4 deployment models  Cloud computing economics Elasticity: Shifting the Risk Comparing Costs: Should I Move to the Cloud?  10 obstacles and opportunities for cloud computing

Cloud Computing

Quantum Computing  Weaknesses in Classical Cryptography - Private key cryptosystems - Public key cryptosystems  Quantum Computing - Parallelism (due to superposition) - Interference (due to entanglement) - Probability (due to measurement) - BQP: Bounded error, Quantum, Polynomial time.  Applications of Quantum Computing - Shor’s algorithm for breaking RSA - BB84 quantum key exchange protocol

Good Luck!