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Other register renaming techniques

ACA Advanced Computer Architectures

Tomasulo implements an implicit register renaming: the code is not changed and there is dynamic loop unrolling. But there are other possible techniques for register renaming Compiler transformation: loop unrolling The compiler unrolls a loop n number of times,...

Speculation and reorder buffer

ACA Advanced Computer Architectures

Hardware-based Speculation Extends the ideas of dynamic scheduling beyond branches combining 3 concepts: Dynamic branch prediction Speculation to enable the execution of instructions before the control dependences are solved by undoing the effects of an incor...

Caches

ACA Advanced Computer Architectures

The main goal of caches is to increase the performance of a computer through the memory system in order to: Provide the user the illusion to use a memory that is simultaneously large and fast Provide the data to the processor at high frequency For this reaso...

Improving cache performance

ACA Advanced Computer Architectures

$$\text{AMAT} = \text{Hit Time} + \text{Miss Rate} \times \text{Miss Penalty}$$ In order to improve the AMAT we need to: Reduce the miss rate Reduce the miss penalty Reduce the hit time The overall goal is to balance fast hits and few misses. 1) Reducting th...

Course information

CS Computer Security

Complete course name: 055633 - COMPUTER SECURITY - UIC 587 (ZANERO STEFANO) Profesor: Stefano Zanero Tutor: Armando Bellante Accademic year: 2021-2022 Recordings: link to webeep Webeep: link to recman Topics Introduction to computer security Cryptog...

Introduction to computer security

CS Computer Security Introduction, authentication and access...

CIA Paradigm The CIA paradigm for information security states three desiderata: Confidentiality: information should be accessed only by authorized entities. Integrity: information should be modifies only by authorized entities, and only in the way such enti...

Authentication

CS Computer Security Introduction, authentication and access...

Identification is when an entity declares its identity ("I am Stefano", "I am Michele", ...) while authentication is whene the entity provides proof that verifies its identity. The threee factors of authentication To know: something that the entity knows. Ex...

Access control

CS Computer Security Introduction, authentication and access...

Reference monitor The reference motior enforces access control policies ("who does what on which resource"). All modern kernels have a reference monitor implementation. The requirements of the reference monitor are: Tamper proof Connot be bypaased Small enout...

Exercises on authentication and access control

CS Computer Security Introduction, authentication and access...

2021-2022 Demo exam exercise 1 (4 points) In a company, each employee works in an open space. We need to design proper policies to minimize the risk that passwords get compromised. Such policies will be enforced whenever a user chooses a new password. Also, as...

Malwares introduction

CS Computer Security Malwares

"Malware" is a portmanteau of "malicious software": code that is intentionally written to violate a security policy. Several categories can be defined: Viruses: code that self-propagate by infecting other files, usually executables. Therefore, viruses are no...

Defending againts malware and stealth techniques

CS Computer Security Malwares

Patches: most worms exploit known vulnerabilities Signatures: must be developed automatically to keep up Intrusion and anomaly detection: notice suspicious activity Antivirus and antimalware The basic strategy is a signature-based detection: database of b...

Exercises on malwares

CS Computer Security Malwares

2021-2022 Demo exam exercise 6 Our systems have been compromised by very powerful malware. Luckily, we managed to collect a sample of the malware. Its code is reported below. .text 0x08048046<do_stuff>: 0x08048046: push ebp 0x08048047: mov esp, ebp 0x080480...

Exercises on introduction

CS Computer Security Introduction, authentication and access...

Question 0 Consider the phenomenon of identity stealing in social networks (e.g., Facebook, Twitter), which happens when a cyber criminal steals the username and password of a user and uses them to impersonate that user (e.g., post content, send messages to fr...