Description for: Homework 1

Cryptography basics

Complete the problems below and submit this word document

Name:

Problem 1 [20pts]:

Assuming 1000 4GHz machines can crack 240 keys per second.

a. How many years would it take to try all possibilities of 64 bit encryption?

b. How many years would it take to try all possibilities of 128 bit encryption?

Problem 2 [40pts]:

Encrypt the message we are all together Using a double transposition cipher (of the type described in the course slides) with 4 rows and 4 columns, using the row permutation (1, 2, 3, 4) -> (2, 4, 1, 3) and the column permutation (1, 2, 3, 4) -> (3, 1, 2, 4).

Problem 3 [40pts]:

NOTE: For Problem 3, you need to attach the source code and the demo video alongside of this word document. You need to encrypt the plaintext below using one of the cipher algorithms we have learned so far (simple substitution, one-time pad, double transposition). To do so, you should use a computer program. The program can be a source code you find on the Internet. But you need to provide a demo video (maximum 3 minutes) to show your understanding of the program (how the program works and encrypts the text).

Plaintext: Cryptanalysis is the study of methods for obtaining the meaning of encrypted information without access to the secret information that is normally required to do so. Typically this involves knowing how the system works and finding a secret key. Cryptanalysis is also referred to as codebreaking or Password cracking the code. Ciphertext is generally the easiest part of a cryptosystem to obtain and therefore is an important part of cryptanalysis. Depending on what information is available and what type of cipher is being analyzed cryptanalysts can follow one or more attack models to crack a cipher.