Vigenere Cipher: Trends, Review and Possible Modifications

Abstract

Vigenere cipher is one of the earliest known polyalphabetic cipher which was considered secure for a very long time until 1917 when friedman and kasiski were able to break it by determining repeating segments of the ciphertext and using it to determine the length of the key. Once the length of the key is known, the ciphertext could be grouped in columns and treated as a separate caesar cipher which can be solved. Over the years, a lot of modification has been done to inprove the security of the vigenere cipher. This paper presents a review of the vigenere cipher and also discusses various existing modifications. General TermsCryptography is the art and science of protecting information from unauthorized individuals.Encryption is a way of converting information (plaintext) into a form that is unreadable to unauthorized individuals (ciphertext).

Modified Vigenère cipher algorithm based on new key generation method

“…However, if the length of the key is equal to the length of the plaintext, then the following formula can be used (4). It is worth mentioning that for decryption process, when the length of key equals the length of ciphertext then the following formula can be used (5).…”

“…As a result, a powerful mathematical encrypting function that an opponent cannot decrypt in real polynomial time is required for secure encryption. Blaise de Vigenère, a French mathematician, came up with an innovative polyalphabetic cipher called the Vigenère cipher, which relates to symmetric encryption [5]. To look at it another way, it was a cipher that could readily be broken using a frequency analysis of letters, like the Caesar cipher.…”

Kriptografi ve Görüntü Steganografi Tabanlı Bir Veri Gizleme Uygulaması: Sten 0.1

“…• Vigenère şifreleme; çoklu alfabe kullanan bir yerine koyma şifreleme türüdür. Alfabedeki harfler satır ve sütun isimlerini ifade etmek üzere bir tablo oluşturulur (Aliyu ve Olaniyan, 2016). Tablonun ilk satırına orijinal alfabe yazılır, daha sonra satırdaki harfler birer kaydırılarak bir sonraki satıra yazılacak alfabe elde edilir ve bu işlem tablonun bütün satırları için tekrarlanır.…”

Encoding syriac letters in partition theory using extended Vigenere cipher

“…The first column from the left also consists of alphabetical letters arranged in the column; the letters represent an encryption key, each containing the row specified by the letter, and are the repetition of the alphabet that appeared from that letter. You can learn more about the history of the cipher and how to use it by [7][8][9][10]. Table 2 Vigenere Table A It can also be represented mathematically by using the following two equations:…”