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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
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
A cryptographic hash function is a numerical function used in cryptography. A cryptographic hash function integrate the message-passing capabilities of hash functions with security features.The term hash function has been used in computer science from quite frequently and it define as a function that compresses a string of arbitrary input to a string of settled length. However if it satisfies some more requirements, thus it can be used for cryptographic applications and then it is called a Cryptographic Hash functions.Cryptographic Hash functions are the most essential tool in the field of cryptography and are used to manage a number of ... Read More
DES is a block cipher. The encryption procedure is create of two permutations (Pboxes) that can be defined initial and final permutations, and 16 Feistel rounds. Each round need a different 48-bit round key produced from the cipher key in accordance with a predefined algorithm.DES is based on the two essential attributes of cryptography including substitution (also known as confusion) and transposition (also known as diffusion). DES includes 16 steps, each of which is known as round.Each round implements the steps of substitution and transposition. DES is a symmetric cryptosystem. A block is be enciphered is inflicted to an initial ... Read More
Data Encryption Standard (DES) is a block cipher algorithm that creates plain text in blocks of 64 bits and transform them to ciphertext using keys of 48 bits. It is a symmetric key algorithm, which defines that the similar key is used for encrypting and decrypting information.DES takes a 64-bit plaintext and produce a 64-bit ciphertext; at the decryption site, DES takes a 64-bit ciphertext and produce a 64-bit block of plaintext. The same 56-bit cipher key can be used for both encryption and decryption.The key nature of DES is that the algorithms is fixed and is public data. However, ... Read More
There are several applications of cryptographic hash function are as follows −Digital Signature − Hand-written signature is a method to prove that a paper file is signed by us and not by someone else. It can prove this and the current hand-written signature is compared with one or more of the earlier handwritten signatures.If there is a match then the recipient of the files can securely accept that the files could not have been endorsed by someone else. In case it is the first time, it can have to prove the identity by means of some recognition card, and necessarily ... Read More
The Secure Hash Algorithm (SHA) was invented by the National Security Agency (NSA) and published in 1993 through the National Institute of Standard and Technology (NIST) as a U.S. Federal Information Processing Standard (FIPS PUB 180).SHA depends on and shares the similar building blocks as the MD4 algorithm. The design of SHA introduced a new process which develop the 16-word message block input to the compression function to an 80-word block between other things.The processing of SHA works as follows −Step 1 − Append padding bits − The original message is padded and its duration is congruent to 448 modulo ... Read More
There are various attacks on DES which are as follows −Differential Cryptanalysis − The main objective of differential cryptanalysis is to view for statistical distributions and patterns in ciphertext to provide deduce element about the key used in the cipher.Differential cryptanalysis is a section of study in cryptography that compares the method differences in input associated to the differences in encrypted output. It can be used basically in the study of block ciphers to decide if changes in plaintext result in any non-random outcomes in the encrypted ciphertext.Related-Key Cryptanalysis − Related-key cryptanalysis consider that the attacker understand the encryption of ... Read More
DES is a strong encryption standard that works on a 64-bits plaintext block and restore a 64-bits ciphertext. Therefore, DES results in a permutation between the 264 possible arrangements of 64 bits, each of which can be either 0 or 1.DES has 16 rounds and it can use the same set of techniques on the plaintext block 16 times. Any round less can create DES vulnerable to differential cryptanalysis.In Data Encryption Standard, the 64 bit plaintext block is subjected to an initial permutation which does not based on the key, whereas the inverse of this permutation completed off the algorithm and ... Read More
SHA stands for secure hashing algorithm. SHA is a modified version of MD5 and used for hashing information and certificates. A hashing algorithm shortens the input information into a smaller form that cannot be learned by utilizing bitwise operations, modular additions, and compression functions.SHAs also help in revealing if an original message was transformed in any way. By imputing the original hash digest, a user can tell if even an individual letter has been shifted, as the hash digests will be effectively different.The important element of SHAs are that they are deterministic. This define that consider the hash function used ... Read More