Q1:
Assume a cipher
message C= 2360514 is the result of encrypting a message
M with
K=5, assuming each digit were
encrypted individually. What is the value of the message M if the message was encrypted using:
A. Mod 7 addition
B. Mod 7
multiplication
C. Mod 7 exponentiation
Q2:
Assume a cipher message C
= 59 is
the result of encrypting a message M using the public key e=<13, 77>.
A.
Verify that d=<37, 77> is the corresponding private key of
e.
B.
Use the efficient exponentiation scheme
described in
RSA to compute M.
NOTE:
To make sure that your answers are
correct, encrypt
the message M and make sure that you get back C.
Q3:
Assume that A and
B, and C are using Diffie-Hellman with p=23
and g = 7.
Let SA = 3
and SB = 5, and SC = 6.
In order to avoid the man-in-the-middle
attach, they deposit their public values PA , PB and
PC
with a trusted authority (TA).
1.
Compute
the public values PA
, PB and PC
2.
Compute
the shared secret between based on the values deposited with the TA
Ø
A and B
Ø
B and C
Ø
C
and A