ECE 543 Project 1: Academic Paper Reading
Objective: The objective of this project is to help you learn the skills for conducting academic research
by applying the security techniques in network protocol design.
Description: In this project, you need to s
2.2 Random J. Protocol-Designer has been told to design a scheme to prevent messages From
being modied by an intruder. Random J. decides to append to each message a hash of that
message. Why doesnt this solve the problem? (We know of a protocol that uses
Chapter 2
2.
Random J. Protocol-Designer has been told to design a scheme to prevent
messages from being modified by an intruder. Random J. decides to append to
each message a hash of that message. Why doesn't this solve the problem? (We
know of a protoco
Chapter 3
2. Token cards display a number that changes periodically, perhaps every minute. Each
such device has a unique secret key. A human can prove possession of a particular such
device by entering the displayed number into a computer system. The comp
5.2 Message digests are reasonably fast, but heres a much faster function to compute. Take your
message, divide it into 128-bit chunks. and 6) all the chunks together to get a 128-bit result.
Do the standard message digest on the result. Is this a good me
Key Distribution - Public Keys
Certification Authority (CA) signs
Certificates
Certificate = a signed message saying I,
the CA, vouch that 489024729 is Radias
public key
If everyone has a certificate, a private key,
and the CAs public key, they can
aut
ECE 543 Project 2a: Implement the Message Digest Algorithm MD5
Implement the message digest algorithm MD5 and test how random the output appears.
For example, test the percentage of 1 bits in the output, or test how many bits of output
change with minor c
Copyright:
Most of the slides are prepared by Radia
Perlman (one of the authors of the textbook)
and provided by Prentice Hall
1
Outline
Introduction
Cryptography
Authentication
Standards and Deployed Systems
PKI, Secure Email, Kerberos, SSL, IPsec, Web
Review of last classes
1
Cipher Block Chaining (CBC)
IV
M2
M3
M4
E
IV
M1
E
E
E
C1
C2
C3
C4
2
CBC
What happens if ci gets lost? Garbled? How much
data gets lost?
Threat 1: How can attacker that sees and can
modify the ciphertext, and knows the plaintext,
Review of last class
1
Public Key Cryptography
Two keys per user: a private key and a public
key. The keys reverse each others effects.
Confidentiality
Encrypt a message for Alice using her public key
Decryption requires her private key
Digital signa
Midterm Exam Arrangement
Time:
6:25pm-8:25pm, March 8, 2016
Location:
Regular Classroom (SB 201)
Details:
1. Contents to be covered: Chapters 1, 2, 3, 4, 5, 6 (sections 6.1, 6.2, 6.3 only), 9, 10
2. It is an Open-Note exam. You can take the lecture slide
Review of last class
1
Cipher Block Chaining (CBC)
IV
M2
M3
M4
E
IV
M1
E
E
E
C1
C2
C3
C4
2
CBC
What happens if ci gets lost? Garbled? How much
data gets lost?
Threat 1: How can attacker that sees and can
modify the ciphertext, and knows the plaintext,
m
Review of last class
1
Types of attacks
Ciphertext only: can brute-force attack if
recognizable plaintext.
Known plaintext
Chosen plaintext
2
Generic Block Encryption
Block cipher
Fixed-length input, fixed-length key
Fixed-length output (the same le
ECE 543 Project 1: Academic Paper Reading
Objective: The objective of this project is to help you learn the skills for conducting academic research
by applying the security techniques in network protocol design.
Description: In this project, you need to s
Chapter 5
2. Message digests are reasonably fast, but here's a much faster function to compute.
Take your message, divide it into 128-bit chunks, and all the chunks together to get a
128-bit result. Do the standard message digest on the result. Is this a
Review of Last Class
1
Chain Building
Obvious how X.509 envisioned it
Call building from target forward, and
from trust anchor reverse
Where should cert be stored:
Building in the forward: with subject,
Building in the reverse: with issuer
Advantage
Class Today
1
Secure In-band Key establishment
Selfish Misbehavior Detection over 802.11
Based Wireless Networks
2
Secure In-band Key establishment
3
Diffie-Hellman Key Exchange
Establish a shared secret
With no prior shared knowledge
Over public chann
Review of Last Class
1
4-msg credentials download
share weak secret W=h(pwd)
Alice
choose A
Alice, cfw_gA mod pW
cfw_gB mod pW, C1
Bob
Store W,
Y=cfw_privpwd
choose B,
challenge C1
K=gAB mod p
h(K, C1)
cfw_YK
2
2-msg credentials download
Alice
agree on g,
Public Key Cryptography
Two keys per user: a private key and a public
key. The keys reverse each others effects.
Encrypt a message for Alice using her public
key
Decryption requires her private key
Generating Digital Signatures requires the
private ke
Review of last class
1
KDC vs CA Tradeoffs
Stealing the KDC database allows
impersonation of all users and decryption of
all previously recorded conversations
Stealing the CA Private keys allows forging
of certificates and hence impersonation of
all use
Review of last class
27
A Summary of RSA
Named after its inventors: Rivest, Shamir, and
Adelman
Uses modular exponentiation
Choose a modulus n and a public exponent e
Public key encryption is:
ciphertext = plaintext e mod n
Public key decryption is:
09/27/2010
2010 Illinois Institute of Technology
Public Key Cryptography
and Zero Knowledge Proof
Lecture 5
Outline
RSA
Encryption/Signature
Parameter discussion
Diffie-Hellman key exchange
Applications of PKC
Encryption for confidentiality
Anyone can en
10/04/2010
2010 Illinois Institute of Technology
Overview of Authentication
Systems and Security
Protocol Design
Lecture 6
RSA Encryption/Decryption
public key <e, n> (n = p*q) :
c = m e mod n, where m in [0, n-1]
private key <d, n> :
m = c d mod n
c d m
Review of last class
1
Intruders: What Can They Do?
Eavesdrop
Impersonate an address and lie in wait
Send Messages
Modify messages in transit
Replay recorded messages
Write malicious code and trick people into
running it (Digital pests)
2
Section: Cryptog
Sample Questions
1. Alice sends an encrypted message to Bob, using columnar transposition
cipher with a key of computer. Bob received the following ciphertext,
CCPEVMMNOOARPSBRESTLEUOL
Assuming Bob share the key of computer with Alice. Please show how
Bob
ECE543
Computer Network Security
Yu Cheng
Illinois Institute of Technology
Spring 2015
1
Course Framework
Instructor
Prof. Yu Cheng, Dept of ECE
[email protected]; (312) 567-7996; Siegel Hall 320
Office Hours: Tuesday/Thursday 3:30pm-4:30pm; and by appointmen
Review of last class
1
Public Key Cryptography
Two keys per user: a private key and a public
key. The keys reverse each others effects.
Confidentiality
Encrypt a message for Alice using her public key
Decryption requires her private key
Digital signa
Review of last class
1
KDC vs CA Tradeoffs
Stealing the KDC database allows
impersonation of all users and decryption of
all previously recorded conversations
Stealing the CA Private keys allows forging
of certificates and hence impersonation of
all use