Problems for week 5-6, Cryptography
1. Verify that the method described in lecture 11 for verifying RSA-PSS signatures is
correct.
2. Peggy and Victor use the Schnorr identification protocol. Peggy happens to use the
same r in two different executions of

Solutions to problems for week 5-6, Cryptography
1. We recall the signing and verification procedures for user Alice with public key (N, e) and
private key d.
To sign message m, Alice proceeds as follows:
Choose random r and compute w = H(m|r).
Compute

Selected Topics in Cryptography
Solved Exam Problems
Enes Pasalic
University of Primorska
Koper, 2013
Contents
1 Preface
3
2 Exam Problems
4
2
1
Preface
The following pages contain solutions to core problems from exams in Cryptography given at
the Faculty

Problems for week 6-7, Cryptography
1. Consider the LFSR of length 3 with tap sequence 011 and initial state 101. Construct
the output sequence.
2. The output sequence of an LFSR of size three starts with 001110. Determine the
complete output sequence. Al

Problems for week 4-5, Cryptography
1. In an adaptive chosen ciphertext attack the Adversary wants to decrypt a message c
and is allowed to ask for, and get, decryption of any message except c. In lecture 6, we
showed that RSA is not secure against such a

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B.Tech.
(sEM. VIrI) EVEN THEORY EXAMINATION 2012_13
CRYPTOGRAPITY AND NETWORK SECURITY
: 3 Hours
Time
Note :-
.
(i)
(ii)
(iir)
Tbtal Marks
Attemp

CSE543/Fall 2007 - Cryptography Mini-Exam
Tuesday, September 25, 2007 Professor Trent Jaeger
Please read the instructions and questions carefully. You will be graded for clarity and correctness. You
have 45 minutes to complete this exam, so focus on those

EXAM questions for the course TTM4135 - Information Security
June 2008
Part 1
This part consists of 8 questions all from one common topic. The number of maximal points
for every correctly answered question is given next to the question. Maximal number of

Solutions to problems for week 4-5, Cryptography
1. We consider ElGamal in a group with generator g. Alice has private key x and public key
X = gx.
Let c = (c1 , c2 ) be the given ciphertext that the Adversary wants to decrypt. We know that
the correspond

Solutions to problems for week 6-7, Cryptography
1. We recall the generic LFSR
cL
s0 , s1 , , sjL1
sjL
cL1
sjL+1
c2
c1
sj2
sj1
c0 := 1
We assume that the problem text gives the tap sequence in the order c1 c2 c3 , i.e. from right
to left in the figure.
Th