Cryptography, winter 2015/16
M ICHAEL N SKEN , S IMON S CHNEIDER
b
it
4. Exercise sheet
Hand in solutions until Saturday, 28 November 2015, 12:00
(10 points)
ur
ity
Exercise 4.1 (OW-KOA).
One-wayness game GOW .
C
C
e
mp
C os e
ut e
r
1. Prepare a key k Ke

Cryptography, winter 2015/16
M ICHAEL N SKEN , S IMON S CHNEIDER
b
it
7. Exercise sheet
Hand in solutions until Saturday, 19 December 2015, 12:00
Exercise 7.1 (PRF PRG).
(4+4 points)
Exercise 7.2 (IND-CPA?).
C
e
ut e
r
Prove that G is a pseudorandom gener

Cryptography, winter 2015/16
M ICHAEL N SKEN , S IMON S CHNEIDER
b
it
7. Exercise sheet
Hand in solutions until Saturday, 19 December 2015, 12:00
Exercise 7.1 (PRF PRG).
(4+4 points)
Exercise 7.2 (IND-CPA?).
C
e
ut e
r
Prove that G is a pseudorandom gener

Cryptography, winter 2015/16
M ICHAEL N SKEN , S IMON S CHNEIDER
b
it
6. Exercise sheet
Hand in solutions until Saturday, 12 December 2015, 12:00
Exercise 6.1 (AES amputated).
(9 points)
ur
ity
As we have already seen during the lectures, AES is an extrem

Cryptography Assignment 1
Exercise 2: Mono Alphabetic Cipher
(i)
Find the frequency of alphabets in the ciphered text.
a. Count the number of alphabets in the ciphered text
b. Find the number of respective occurrences.
c. Find the frequency using above da

Cryptography Assignment 1
Exercise 2: Mono Alphabetic Cipher
(i)
Lette
r
T
X
D
F
N
Y
K
H
G
E
J
M
U
W
C
Q
R
A
I
P
V
O
B
S
Z
L
Find the frequency of alphabets in the ciphered text.
a. Count the number of alphabets in the ciphered text
b. Find the number of

Cryptography Assignment 2
1.Decrypt Vigneres cipher
2. Comment on one-time pad cipher
Pradeep Kumar Gangatharan
Mat. No: 362105
1. Decrypt the cipher text using Vigneres cipher :
i)
Consider only the alphabets in the cipher texts. Ignoring the numbers and

Cryptography Assignment 4
Pradeep Kumar Gangatharan
4.1) OW-KOA
The definition of the Oracle test encryption is as follows:
= (KGen, Enc, Dec)
KGen is executed on the security parameter 1k to create key K
A uniformly random m is taken from Message space

Cryptography Assignment 3
3.1 Visual Cryptography
i) Represent VC.
ii) Prove that it is perfectly secret.
3.2 To prove no encryption scheme satisfies the given definition
prob (M = m M = m |C = c C = c ) = prob (M = m M = m ).
Name : Pradeep Kumar Gangath

Cryptography Assignment 3
3.1 Visual Cryptography
i) Represent VC.
ii) Prove that it is perfectly secret.
3.2 To prove no encryption scheme satisfies the given definition
prob (M = m M = m |C = c C = c ) = prob (M = m M = m ).
Name : Pradeep Kumar Gangath

Cryptography Assignment 2
1.Decrypt Vigneres cipher
2. Comment on one-time pad cipher
Pradeep Kumar Gangatharan
Mat. No: 362105
1. Decrypt the cipher text using Vigneres cipher :
i)
Consider only the alphabets in the cipher texts. Ignoring the numbers and

Cryptography Assignment 4
Pradeep Kumar Gangatharan
4.1) OW-KOA
The definition of the Oracle test encryption is as follows:
= (KGen, Enc, Dec)
KGen is executed on the security parameter 1k to create key K
A uniformly random m is taken from Message space