Problem 6
To encrypt data of variable length, use padding with CBC mode. To avoid any ambiguity,
make it standard practice always to add padding.
If your plaintext data is always a fixed length equal to a multiple of the block size (8 or
16), you can avoi
Classical
Encryption
Techniques
Raj Jain
Washington University in Saint Louis
Saint Louis, MO 63130
Jain@cse.wustl.edu
Audio/Video recordings of this lecture are available at:
http:/www.cse.wustl.edu/~jain/cse571-11/
Washington University in St. Louis
CSE
Course: Security and Privacy on the Internet
Fall 2007
ASSIGNMENT # 3
Submitted by:
Rachita Singh
Finding the question:
Character
R
a
c
h
i
t
a
S
i
n
g
h
SUM
(1205 mod 23)+1
ASCII Code
82
97
99
104
105
116
97
83
105
110
103
104
1205
10
Question 10.
Assume
M 3
5 2
1 4
3 1
1 4
3 2
2 5
5
2
3
4 3
2 5
4 1 4
5 3 1
b. Assume a plaintext message p is to be encrypted by Alice and sent
to Bob. Bob makes use of M1 and M3, and Alice makes use of M2.
Bob chooses a random number, k, as his private key, and maps k by
M
Secret Key
Cryptography
Raj Jain
Washington University in Saint Louis
Saint Louis, MO 63130
Jain@cse.wustl.edu
Audio/Video recordings of this lecture are available at:
http:/www.cse.wustl.edu/~jain/cse571-09/
Washington University in St. Louis
CSE571S
5-1