These digraphs follow a simple pattern for transforming into a matrix. They are represented in the vector or key matrix form as below. Here, the input message is SHORTER EXAMPLE with key as HILL and from the table, we can take: And for longer than 4 words, the first four letters are used in the matrix.įollowing the above, in the letter and number table, each of the letters is then converted into a specific number in parallel with its position. Depending on the length of the keyword, if it is shorter than three words, then fill it up in alphabetical order. In this process of Hill Cipher, 2×2 matrix, the primary step starts with a keyword that we must convert into a matrix.

Subsequently, for decryption, each block needs to be multiplied by the inverse matrix. Letterįor encrypting a message, one starts with each block having n letters and then multiplied with an n x n matrix, in parallel with modulus 26. Generally, the below-mentioned structure of numbers and letters are used in the Hill Cipher Encryption, but this can be modified as per requirement. Here, we have used simple examples that provide in-depth knowledge on this topic. Although it can be used for higher matrices (4×4, 5×5, or 6×6) as well, it requires a higher and advanced level of mathematics, adding more complexity. We will study both procedures for Hill Cipher encryption and decryption in solving 2×2 and 3×3 matrices. Thus, most of the problems and solutions for Hill Ciphers are of mathematical nature, which also makes it easy to withhold or hide letters precisely. As a prerequisite, it would be better for learners and professionals to have a sound understanding of both linear Algebra and Matrices. Hill Cipher is based on a particular mathematical topic of linear Algebra and the sophisticated use of matrices in general, as well as rules for modulo arithmetic. Here, polygraphic substitution cipher defines that Hill Cipher can work seamlessly with digraphs (two-letter blocks), trigraphs (three-letter blocks), or any multiple-sized blocks for building a uniform cipher. In the pretext of classical cryptography, Hill Cipher represents a polygraphic substitution cipher that follows a uniform substitution across multiple levels of blocks. Hill Cipher is Digraphic in nature but can expand to multiply any size of letters, adding more complexity and reliability for better use. Hill Cipher in cryptography was invented and developed in 1929 by Lester S. Despite modern advancements, Hill Cipher provides a simple and unique way for hiding messages in plain sight.

Hill Cipher has figured out several primary methods in classical cryptography, using multiple methods of mathematics. Several methods have emerged in the history of cryptography that built the fundamentals of modern algorithms. Cyphers were a common concept to deliver secret messages in the early days. Various aspects, such as authentication, data integrity, confidentiality, etc., play a crucial role in modern cryptography concepts. Cryptography is the science of studying and practising communication securely by using unique methods, thus preventing any third person or organisation from accessing any kind of sensitive information.

Hill cipher decryption tool