Security

Feistel block cipher is a structure used to derive many symmetric block ciphers such as DES which we have discussed in our previous content. Feistel cipher proposed a structure which implements substitution and permutation alternately to obtain cipher text from the pain text and vice-versa. In the Feistel block cipher, each block has to undergo many rounds where each round … [Read more...] about Feistel Block Cipher

Block cipher is an encryption and decryption method which operates on the blocks of plain text, instead of operating on each bit of plain text separately. Each block is of equal size and has fixed no of bits. The generated ciphertext has blocks equal to the number of blocks in plaintext and also has the same number of bits in each block as of plain text. Block cipher uses the … [Read more...] about Block Cipher

Data Encryption Standard (DES) is the symmetric block cipher which encrypts a 64-bit plain text in a 64-bit ciphertext. The DES was introduced by the National Institute of Standard and Technology (NIST) in the 1970s. Initially, DES was only used in financial applications but later it was accepted as the cryptographic algorithm by other organizations too. Being a symmetric … [Read more...] about Data Encryption Standard (DES)

Transposition technique is an encryption method which is achieved by performing permutation over the plain text. Mapping plain text into cipher text using transposition technique is called transposition cipher. In this section, we will discuss variations of transposition technique, and we will also observe how the transposition technique is different from the substitution … [Read more...] about Transposition Technique in Cryptography

Substitution technique is a classical encryption technique where the characters present in the original message are replaced by the other characters or numbers or by symbols. If the plain text (original message) is considered as the string of bits, then the substitution technique would replace bit pattern of plain text with the bit pattern of cipher text. We will discuss … [Read more...] about Substitution Technique in Cryptography