Introduction to Cryptography with Coding Theory, 3rd Edition

C.10 Examples for Chapter 18

Example 39

Here is a game you can play. It is essentially the simplified version of poker over the telephone from Section 18.2. There are five cards: ten, jack, queen, king, ace. We have chosen to abbreviate them by the following: ten, ace, que, jac, kin. They are shuffled and disguised by raising their numbers to a random exponent mod the prime 300649. You are supposed to guess which one is the ace.

First, the cards are entered in and converted to numerical values by the following steps:

>> cards=[’ten’;’ace’;’que’;’jac’;’kin’];

>> cvals=text2int1(cards)

cvals =

   200514
   10305
   172105
   100103
   110914

Next, we pick a random exponent $k$ that will be used in the hiding operation. We use the semicolon after khide ...