SCSC 455 Quiz 3 – Take Home (50 pts, 30 minutes) Name _______________________
Due: Apr 20 for MW section / Apr21 for TTh section
1 Fill in blanks (10 pts)
1) It is computationally infeasible to find x such that H(x) = h. A hash function with this property is
referred to as _________________________________.
2) It is computationally infeasible to find any pair (x, y), such that H(x) = H(y). A hash function with
this property is referred to as _____________________________________.
3) Based on birthday paradox, an attacker needs approximately _________________computation
to find a collision on a hash function generates 100-bit hash value.
4) NIST has published FIPS PUB 186, known as the _______________________________. It makes
use of the SHA-1 and presents a new digital signature technique, the Digital Signature Algorithm.
5) Three new versions of SHA with hash value lengths of 256, 384, and 512 bits. Collectively, these
hash algorithms are known as ____________________.
2. 1) What is the procedure of D-H key exchange algorithm?
1
(10 pts)
2) Could we say D-H key exchange algorithm is flawed, since it is susceptible to man-in-themiddle attack? Why or why not?
3. What are the pros and cons of asymmetric cryptosystem? (10 pts)
4 1) Write the formula of hybrid cryptosystem. (10 pts)
2
2) What are the advantages of hybrid cryptosystem?
5. What are the reasons for the interest in developing a technique that avoids encryption
altogether in message authentication? (10 pts)
3