1. Uses that use matrices Second, how significant are they, and third, what cryptographic applications may they have? There ought to be at least five complete sentences in each paragraph.

Symmetric and asymmetric algorithms are distinguished by the types of keys used for encryption and decryption operations. Briefly describe how this works.

Describe the steps involved in mounting a statistical attack on a monoalphabetic substitution cipher. (please do not explain it with pictures) Explain why this approach would fail on a polyalphabetic substitution cipher?

b.What is the maximum amount of time that it would take a computer that can test  keys per second to carry out a brute-force attack on a file encrypted using 256-bit AES? Give your answer in seconds and years, using scientific notation, correct to 2 significant figures. You may assume a year is seconds and you may use a calculator to help work out the answer. Show all your working clearly in a way that will help your tutor understand how you arrived at your answer.

1. Asymmetric Encryption and Message Authentication:      a) The primitive root of a prime number is the basic principle of Diffie-Hellman.         i) Is 3 the primitive root of 11? Show the proof with your calculation.        ii) What are the important criteria for selecting a prime number in cryptography? Is 11 a good choice for such a purpose?    b) Find the parameters stated using the Diffie-Hellman methods, given the user A and B shared a prime number and its primitive root of 23 and 5, respectively.         i) If user A public key value is 8, find the A’s private key.        ii) If user B public key value is 19, what is the common secret key?   c) In the following scenario, we will compare the security services that are given by digital signatures (DS) and message authentication codes (MAC). We assume that James can read all messages send from Chan to Badrul and the other way around, too. James has no knowledge of any keys but the public one in the case of DS. State whether and…

Now assume that the user used only 34 characters from the keyboard. What is the key length in bits in this case? Provide the correct answer for the fourth question. This is not a graded assignment.

10. What would Kasiski's method suggest concerning the length of the key for the ciphertext: "PRUTAECDERUTFGHJKGUILRUTI". EXPLAIN the computation in detail!

1. Uses that use matricesSecond, how significant are they, and third, what cryptographic applications may they have?There ought to be at least five complete sentences in each paragraph.

Calculate the key space for 128-bit keys and compare that to the key space for 10-character passwords (lower case English alphabetic, upper case English alphabetic, 10 digits and 14 special characters are allowed). How many characters does a password following the above rules must have to achieve the same or better security as 128-bit random keys if the passwords would be chosen randomly?

Let k be the encipherment key for a Caesar cipher. The decipherment key is 26 – k.One of the characteristics of a public key cryptosystem is that the encipherment anddecipherment keys are different. Explain why the Caesar cipher is a secret keycryptosystem, not a public key cryptosystem?