“…Various classical ciphers such as Railfence cipher [13], [14], Polybius square cipher [15]- [19], Playfair cipher [20]- [22], Permutation cipher [23], Homophonic substitution cipher [24], [25], Hill cipher [26], Grille cipher [27], Four-square cipher [23], Enigma machine cipher [23], Caesar cipher [28]- [30], Base64 cipher [31]- [33], Affine cipher [23], [34]- [36], and ADFGVX cipher [23], [37]- [39] to name some, are being incorporated with block ciphers, among others, to solve the constraints in IoT. Among the classical ciphers, the Polybius Cipher, known as the Polybius square, is identified as one of the commonly used methods for such purpose [40]- [42].…”