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
PKI Certificate:
Create a certificate
request (as described in OpenSSL PKI lecture) and submit it to cs772
for signature.
Secure
Mail:
Use OpenSSL SMIME to mail your solution for Q1,Q2 and Q3 to cs772 as signed and encrypted message as follows:
Let <login>A3.xxx (xxx may be txt, pdf,
doc, etc) is a file that
contains your answers.
% zip <login>A3 <login>A3.xxx
%
zipsendsign_encmail-sh cs772
<login>A3 <login>
This script mail to
cs772 the file <login>A3.enc
To make sure your steps are correct,
mail the file to your <login> and then save the received
file into a file F.
Use the command:
%
zipreadsign_encmail-sh <login>
F
In addition, since the email can be lost use:
% submit cs772
to submit the file <login>A3.enc under Assignment#3.