CSCI 391 Practical Cryptology Spring 2015
RSA TEST Part 2

Answer all questions. Provide detailed explanation.
Open Material

IMPORTANT: Use base 26 system while converting strings to numbers

For numeric values of letters see HERE
  1. (20 points) Find 23^73 mod 19 using fast modular exponentiation. Write your calculations for all steps.
  2. (20 points) True or False: with m = 24589181 and e= 13 it is possible to encrypt any all 5-letters words. Explain your answer.
  3. (20 points) Alice publishes m = 22771241 and e = 13. And Bob would like to encrypt plaintext GAME. Encrypt the message or explain why it is impossible.
  4. (20 points) Suppose you know m = 22771241 and e = 13. Find p, q and d and decrypt the following message: BNKGLK
  5. (20 points) Suppose you know m = 192469, n = 191296 and e = 11. Find p and q using quadratic equation solutions. Find d and decrypt the message EVEG.