22 block cipher modes of operation part 1 cns

Download 1M+ code from https://codegive.com/ae2ad74 okay, let's dive into the fascinating world of block cipher modes of operation! we'll cover a significant chunk of them (22, as requested) while focusing on the core concepts and practical implementations. due to the length, this is part 1. **important preliminary notes** * **block ciphers:** a block cipher (like aes, des, or blowfish) operates on fixed-size blocks of data (e.g., 128 bits for aes). modes of operation extend the use of a block cipher to encrypt data of arbitrary length. * **key concepts:** * **encryption:** the process of transforming plaintext (readable data) into ciphertext (unreadable data). * **decryption:** the reverse process, transforming ciphertext back into plaintext. * **initialization vector (iv):** a non-secret random value used to ensure that encrypting the same plaintext multiple times produces different ciphertexts. crucial for modes like cbc, cfb, ofb, and ctr. *must be unpredictable (ideally random) for security.* * **padding:** since block ciphers operate on fixed-size blocks, padding schemes are often used to ensure the plaintext length is a multiple of the block size. common padding schemes include pkcs7/pkcs5. * **nonce:** a "number used once." similar to an iv, but often used with authenticated encryption modes. sometimes predictable, but must be unique for each encryption operation using the same key. * **authenticated encryption:** modes that provide both confidentiality (encryption) and integrity (authentication). they ensure the data hasn't been tampered with. * **parallelizability:** the ability to perform encryption or decryption of different blocks concurrently. * **error propagation:** the extent to which an error in one ciphertext block affects the decryption of subsequent blocks. * **library:** we'll use `cryptography` library, which you can install using pip: `pip install cryptography`. **part 1: the fundamental modes** 1. **electronic codebook ( ... #BlockCipher #Cryptography #python block cipher modes of operation encryption decryption cryptography symmetric key CBC mode ECB mode CFB mode OFB mode CTR mode GCM mode authentication security data integrity