Brute Force Bayes Algorithm
Here is a basic Bayes rule decision algorithm:
Initialize H a set of hypothesis such that h0hn H
For each hi in H calculate the posterior probability
p(hi|D) = p(D|hi) * p(hi)
p(D)
Output MAX(h0hn)
Nave Bayes Classifier
This cl
Chapter 2
COMPUTER SECURITY
AND INTRUSION DETECTION
The scenario in the previous section described an exemplary threat to computer system security in the form of an intruder attacking a companys web
server. This chapter attempts to give a more systematic
Computer Security
Basic Computer Security Practices
Make backups of important files.
Apply patches to the operating system.
Use anti-virus software, update definitions very frequently, and run a full virus scan at least once a
month.
Use a firewall.
Use a
Introduction
- some basic concepts and terminology
- examples for attacks on protocols
- main network security services
(c) Levente Buttyn ([email protected])
Attack, threat, and vulnerability
security is about how to prevent attacks, or - if prevention i
Lecture 2
Confidential Channels, Encryption
and Ciphers
CNT 5412
Network Security
1
Cryptography
Greek for hidden writing
The art and science of keeping messages
secure
A field of study relating to the above
Note: Cryptology is often defined to includ
Lecture 3
Block Ciphers and Modes of Operation
CNT 5412
Network Security
1
Block Cipher
A block cipher E() is a (parametrized) deterministic
function mapping n-bit plaintext blocks to n-bit ciphertext
blocks. The value n is called the blocklength.
It is
Practical attacks against
WEP and WPA
Martin Beck, TU-Dresden, Germany
<[email protected]>
Erik Tews, TU-Darmstadt, Germany
<e [email protected]>
November 8, 2008
In this paper, we describe two attacks on IEEE 802.11 based wireless
L
CNT 5412
Network Security
(Partial) Midterm 1 Sample Questions
February 2012
NAME_
Instructions:
Put your name on your exam.
Do all problems. Points are indicated next to the problem.
1. 16 pts
2. 16 pts
3. 12 pts
4. 28 pts
1. (16 pts) You know that the f
Lecture 9
Public Key Cryptography
Public Key Algorithms
CNT 5412
Network Security
1
Eulers Totient function (n) - again
(n) is the number of positive integers less than n and
relatively prime to n.
Let p be a prime. Then (p) = p 1
Let n = pq for p and q
Lecture 8
Public Key Cryptography
Introduction to Number Theory
CNT 5412
Network Security
1
Public Key Cryptography
Also called asymmetric key systems
Unlike symmetric key, there is no need for Alice
and Bob to share a common secret
Alice and Bob can c
Lecture 7
Authentication / Authorization Systems
and Kerberos
CNT 5412
Network Security
1
Needham and Schroeder Paper
1978
Seminal paper on Cryptographic Protocols
Identified several "canonical" protocols
including for authentication
Accidentally illust
Lecture 6
Authentication
CNT 5412
Network Security
1
Authentication: who and how
User (human) can be authenticated
logging into a workstation
using resources of a system
issues: humans find it difficult to remember arbitrary strings
Computer can be a
Lecture 5
Applications of Secret Key Cryptography
Message Authentication Codes
and
Cryptographic Hash Functions
CNT 5412
Network Security
1
Cryptographic hash functions
Also called message digests
Map a large space of values to a small space
Cannot be eas
Lecture 3
Block Ciphers and Modes of Operation
CNT 5412
Network Security
1
Block Cipher
A block cipher E() is a (parametrized) deterministic
function mapping n-bit plaintext blocks to n-bit ciphertext
blocks. The value n is called the blocklength.
It is
Lecture 2
Confidential Channels, Encryption
and Ciphers
CNT 5412
Network Security
1
Cryptography
Greek for hidden writing
The art and science of keeping messages
secure
A field of study relating to the above
Note: Cryptology is often defined to includ