Modern cryptographic algorithms play an important role in our daily lives by providing secure communication online. Before modern algorithms, there were classical ciphers, such as the Vigen`ere and Caesar cipher. In modern time, these ciphers are considered vulnerable to a number of cryptanalytic techniques and attacks, such as pattern analysis and brute-force attacks. In this thesis, we propose a modification to the Vigen`ere cipher, in which we enhance its durability to pattern analysis. The modification applied confusion to the cipher by adding additional letters, in English, which we refer to as padding in this thesis, to the encrypted message with the goal of concealing the letter frequency distribution of the cipher text. The performance of the method is evaluated on the accuracy with which the encrypted message is decrypted, the entropy score, and its durability against cryptanalysis. The finding includes a 100% decryption accuracy rate and an entropy of ≈ 4.7004 bits. A drawback of the algorithm is that the encrypted message may be longer than the message due to the added padding.