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COUNTERPANE SYSTEMS
WHY CRYPTOGRAPHY IS

HW2 ISA 562
John Tigmo
Due Wed 09/28
Chapter 3 Questions 3,5,8
Q3) How many DES keys, on the average, encrypt a particular plaintext block to a
particular ciphertext block?
ANSWER:
For each plaintext block there are 256 possible keys and 264 ciphertext bl

ISA 562
Homework 3
John Tigmo
Chapter 6: 1, 3, 8, 9
1. In mod n arithmetic why does x have a multiplicative inverse if and only if x is
relatively prime to n?
ANSWER:
If a and b are relatively p

ISA 562 Spring 2016: Homework 3
Brashier.
Chapter 2:
3: This would be more secure than having them all use the same secret key K.
When using the same key any of the other 2 could respond correctly to the
challenge. However, if they each had their own uniq

ISA 666
ISA 562: Public Key
algorithms
Chapter 6 from Kaufmann et. al.
1
ISA 562
2
Outline
Concepts of Public Key Cryptosystems
Applications of Public Key Cryptosystems
Number theory underlies most of public key algorithms.
Well-known Public Key Crypt

ISA 562
Homework 3
John Tigmo
Chapter 6: 1, 3, 8, 9
1. In mod n arithmetic why does x have a multiplicative inverse if and only if x is
relatively prime to n?
ANSWER:
If a and b are relatively prime numbers then we can say u*a + v*b = 1. Then, we
can calc

John Tigmo
ISA 562
Homework 1
Due 9/14/2016
Chapter 2 problems 1, 3,5,6
Problem 1.
What is the dedication to this book?
Si spy net work, big fedjaw iog link kyxogy
The first word has to be To since its a dedication
If it is a substitution method the next

ISA 562, Fall 2016
Information Security
Theory and Practice
Duminda Wijesekera
[email protected]
(703) 993-5030
Yours truly,
Name = Duminda Wijesekera
Web = http:/www.gmu.edu/~duminda
Email = [email protected]
Phone = (703) 993-5030
Office = Room 436,

ISA 562, Spring 2016: Homework Set 2
Michael Brashier
Problems from Textbook, Chapter 7: 2, 3, 4, 9
Problems from Chapter 8: 8.1, 8.4, 8.5, 8.18, 8.24, 8.26
7.2
a) An attacker could potentially access or modify O by finding the reference name of O

HW2 ISA 562
John Tigmo
Due Wed 09/28
Chapter 3 Questions 3,5,8
Q3) How many DES keys, on the average, encrypt a particular plaintext block to a
particular ciphertext block?
ANSWER:
For each plaintext bl

Michael Brashier
ISA 562, Spring 2016: Homework Set 4
Out: March 29, 2016. In: April 11, 2016 All questions carry equal
weight.
The Chapter References are for the course textbook, Network Security
by Kaufmann et al.
Chapter 3
3.page 92
How many DES keys,

1
ISA 562: AUTHENTICATING
SYSTEMS + PEOPLE
Chapter 9-10 of Kaufmann et al.
2
Identification
Identification is a process through which one
ascertains the identity of another person or entity.
Identification requires establishing the uniqueness
of an enti

Review for Exam 2
Subject matter:
Chapters from Bishops book:
Covers topics not included in Exam 1
RBAC and Chinese Wall Policies
Cryptography
Network Security and Authentication
7, 9, 10, 11, 12
The nature of the exam:
4-5 questions
Similar to the homewo

ISA 562: Hashes and Message Digests
Chapter 5 from Kaufmann et al
1
Requirements for a Hash Function
Consider a hash function H
Flexibility: Can be applied to a block of data of any size
Convenience (for check): produce a fixed-length short
output.
Pe

John Tigmo
ISA 562
Homework 1
Due 9/14/2016
Chapter 2 problems 1, 3,5,6
Problem 1.
What is the dedication to this book?
Si spy net work, big fedjaw iog link kyxogy
The first word has to be To since its a dedication
If it is a substitution method the next

ISA 562, Spring 2016: Homework Set 2
Michael Brashier
Problems from, Chapter 8:
8.1
a) I would define a relation of L(Li ) L(U) for the label L where L(U), the
clearance level of the User, is greater than or equal to either Si , Ci. In this way it

ISA 562, Spring 2016: Homework Set 1
Out: January 20, 2016. In: February 04, 2016 All questions carry equal weight.
Michael Brashier
Introductory Chapter: 1.2, 1.3, 1.8
Chapter 7
7.7, 7.10, 7.12
1.2
Classify each of the following as a violation of

ISA 562: Introducing
Cryptography
Chapter 2 from Kauffman, Pearlman & Speciner
2
Cryptography
Cryptography
Comes from Greek word
Original meaning: The art of secret writing
Becoming a science that relies on mathematics (number theory,
algebra)
Proces

RYAN JOHN
G00850394
ASSIGNMENT 1
Exercise 1.8
1) Classify each of the following as a violation of confidentiality, of integrity, of
availability, or of some combination thereof.
a. John copies Mary's homework.
The case mentioned is a violation of Confide

1
ISA 562: BLOCK
CYPHERS
MODES
OF OPERATION
Chapters 3 and 4 from
Kaufman, Pearlman and Speciner
ISA 562-Addiional Material
2
Topics
Generic Block Cipher
DES
Modes of Block Ciphers
Multiple Encryptions
Message Authentication through Secret Key
Crypto

1
ISA 562: Number theory
Chapter 7 from Kaufmann et al
2
Recommended Reference text on Number theory for
Cryptography
Number Theory for Computing
Second edition
Song Y. Yan
Springer-Verlag,
ISBN = 3-540-43072-5
Not necessary to read!
3
Basic Number