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communicate securely. It is widely used in today's society. (The question is more long than hard.)

Every character of the alphabet is turned into a number: We assign the letters of the alphabet

A,B,C,...,Y,Z with the numbers 0, 1, 2,..., 24, 25, respectively.

In this small version of RSA, we'll deal with 2 letters at a time: every pair of letters can be uniquely

represented by a number less than 676 in base 26. Every pair of letters corresponds to some number

between 0 and 675 inclusive, and any such number corresponds to a pair of letters.

For example, to convert DISCRETE into numbers we would do the following: DI SC RE-TE

becomes

D is 3, I is 8: so DI is 3 x 26+8 = 86.

S is 18, C is 2: so SC is 18 x 26+2 = 470.

R is 17, E is 4: so RE is 17 × 26 +4= 446.

T is 19, E is 4: so TE is 19 × 26 + 4 = 498.

Thus, DISCRETE would be written 86 470 446 498.

Fig: 1