This dissertation discusses modification of Vigenère cipher which works by adding a key repeatedly into the plaintext using the convention that A = 0, B = 1, . . . , Z = 25; and addition is carried out modulo 26that is, if the result is greater than 25, we subtract as many multiples of 26 as are needed to bring us into the range [0, . . . , 25], that is, [A, . . . , Z]. Mathematicians write this as: C = P + K mod 26 .For modification of Vigenère cipher, numbers, punctuations, mathematical

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... s may be used for key in place of characters. Random generated numbers may be used to spread the encrypted message.