block cipher standards des

Download 1M+ code from https://codegive.com/f0ec264 understanding des (data encryption standard) **overview:** data encryption standard (des) is a symmetric-key block cipher that was widely used for data encryption. it encrypts data in fixed-size blocks of 64 bits using a 56-bit key. although des was considered secure in its early years, it is now deemed obsolete due to advancements in computing power that make it vulnerable to brute-force attacks. **key features:** - **block size:** 64 bits - **key size:** 56 bits (often represented as 64 bits, including 8 parity bits) - **structure:** des operates in 16 rounds of processing, involving substitution and permutation steps. - **symmetric key:** the same key is used for both encryption and decryption. des encryption process 1. **initial permutation (ip):** the 64-bit block is rearranged. 2. **key generation:** the 56-bit key is used to produce 16 subkeys, one for each round. 3. **rounds:** each round consists of: - expansion: the right half (32 bits) is expanded to 48 bits. - substitution: the expanded block is divided into 8 segments, each substituted using an s-box. - permutation: the substituted output is permuted. - mixing: the left and right halves are mixed and processed for the next round. 4. **final permutation (fp):** another permutation is applied to the output of the last round to produce the ciphertext. example code we can use the `pycryptodome` library in python to implement des. first, ensure you have it installed: here’s a simple example demonstrating how to encrypt and decrypt data using des. explanation of the code 1. **key and initialization:** - we define an 8-byte key (`key`), which is required for des encryption. - we create a des cipher object using the `des.new()` method with cbc (cipher block chaining) mode. 2. **padding:** - since des operates on blocks of 8 bytes, we pad the plaintext to ensure it meets this requirement using the `pad()` function. 3. **encryption:** - the padded plaintext is encrypted ... #BlockCipher #DES #axios Block cipher DES data encryption symmetric key cryptography encryption standard block size key length security algorithms cryptographic standards Feistel network plaintext ciphertext key schedule cryptanalysis