The Double DES uses two example of DES cipher for encryption and two units of reverse DES cipher for decryption. Each unit of DES cipher needs multiple key for encryption which enhance the size of the key (112 bit) creating it more secure. But in the double DES can be destroyed by known plaintext attack known as meet-in-themiddle attack.Given a plaintext P and two encryption keys K1 and K2, ciphertext C is produced as C = Ek2(Ek1, (m)) decryption needed that the keys be used in reverse order −P = Dk1(Dk2, (C))A Meet-in-the-Middle (MitM) Attack is a type of cryptanalytic ... Read More

Data Encryption Standard (DES) is a block cipher algorithm that takes plain text in blocks of 64 bits and transform them to ciphertext utilizing keys of 48 bits. It is a symmetric key algorithm. It can define that the same key can be used for encrypting and decrypting data.The design of DES was invented by IBM in 1994. There are some tests on DES have proved that it satisfies some of the required element as claimed. There are some design issued which are as follows −S-Boxes − S-Boxes is a procedure that accepts the 48-bit input from the XOR operation ... Read More

The Data Encryption Standard (DES) is a symmetric key block cipher which creates 64-bit plaintext and 56-bit key as an input and makes 64-bit cipher text as output. The DES function is create up of P and S-boxes. P-boxes transpose bits and S-boxes substitute bits to make a cipher.DES is a Feistel Block Cipher implementation, called a LUCIFER. It need a Feistel structure with 16 rounds, where a different key can be used for each round. The major reasons to understand DES (Data Encryption Standard) is that it forms the foundation for encryption algorithms. This creates it easy for one ... Read More

DES is a block cipher. The encryption procedure is create of two permutations (Pboxes) that it can be defined initial and final permutations, and 16 Feistel rounds. Each round need a different 48-bit round key created from the cipher key according to a pre-represented algorithm. The DES function uses a 48-bit key to the rightmost 32 bits (RI−1) to create a 32-bit output.There are two properties of DES which are as follows −Avalanche EffectAvalanche effect defines a small change in the plaintext (or key) should make an important change in the ciphertext. It can change in one bit of plaintext ... Read More

There are two main variations of Data Encryption Standard are as follows −Double DES − Double DES is an encryption approach which need two instance of DES on same plain text. In both instances it uses multiple keys to encrypt the plain text. Both keys are needed at the time of decryption.The 64 bit plain text goes into first DES instance which than transformed into a 64 bit middle text utilizing the first key and thus it goes to second DES instance which provides 64 bit cipher text by utilizing second key.Double DES is easy as it does that normal ... Read More

There are various elements of DES which are as follows −Use of S-Boxes − The tables used for substitution i.e., the S-boxes, in DES are kept hidden by IBM. IBM supports that it took them over 17 person years to appear up with the internal design of the S-boxes.Key Length − Cryptographic system has two important elements including the cryptographic algorithm and the key. The inner operating of the DES algorithm are completely popular to the general public. Hence, the strength of the DES lies only in the other element including its key, which should be secret.Differential Cryptanalysis − Differential ... Read More

This operation expands the right half of the information, R from 32 bits to 48 bits and this operation changes the order of the bits as well as repeating specific bits. It is called an expansion permutation.This operation has two objective including it creates the right half the similar size as the key for the XOR operation and it supports a longer result that can be compressed during the substitution operation. It can be enabling one bit influence two substitutions, the dependency of the output bits on the input bits spread quicker. This is known as avalanche effect.DES is designed ... Read More

DES uses 16 rounds. Each of the 16 rounds includes the broad-level steps are as follows −Key Transformation − An initial 64-bit key is changed into a 56-bit key by discarding each 8th bit of the initial key. Therefore for each round, a 56 bit key is available. From this 56-bit key, a different 48-bit subkey is generated during each round using a process is known as key transformation.The 56-bit key is divided into two halves, each of 28 bits. These halves are circularly shifted left by one or two positions, based on the round.For instance, if the round number ... Read More

A cryptographic hash function is a transformation that creates an input (or message) and restore a fixed-size string, which is known as the hash value. A hash value h is produced by a function H of the form −h = H(M)where M is the variable length message and H (M) is the fixed length hash value.Hash functions are generally used mathematical functions in cryptography for executing security. A hash function transform an input value of any arbitrary size to a fixed-size value. Therefore, the input can be of any length but the output produced is always of a fixed length. ... Read More

An initial permutation is required only once at the starting of the encryption process. In DES, after the complete plaintext is divided into blocks of 64 bits each, IP is required on each of them. This initial permutation is a phase in the transposition procedure.The initial permutation appears only once, and it appears before the first round. It recommend how the transposition in IP should proceed, as display in the table.For example, it can said that the IP restore the first bit of the original plain-text block with the 58th bit of the original plaintext block, and the second bit ... Read More