Cryptography Questions Medium
The Electronic Codebook with Cipher Feedback (ECB-CFB) mode is a hybrid encryption mode that combines the Electronic Codebook (ECB) and Cipher Feedback (CFB) modes.
In ECB mode, the plaintext is divided into blocks of fixed size, and each block is encrypted independently using the same key. This mode is simple and efficient but lacks security as identical plaintext blocks result in identical ciphertext blocks.
To address this vulnerability, CFB mode is introduced. In CFB mode, the previous ciphertext block is encrypted and then combined with the plaintext block using XOR operation to produce the ciphertext block. This ensures that even identical plaintext blocks will have different ciphertext blocks.
In ECB-CFB mode, the encryption process starts with an initialization vector (IV) and the previous ciphertext block. The IV is encrypted using the key to produce the first ciphertext block, which is then combined with the first plaintext block using XOR operation to produce the first encrypted block. This process continues for subsequent blocks, where the previous ciphertext block is encrypted and combined with the current plaintext block to generate the encrypted block.
ECB-CFB mode provides confidentiality and ensures that identical plaintext blocks do not result in identical ciphertext blocks. However, it does not provide integrity or authentication, making it vulnerable to certain attacks such as bit-flipping attacks. Therefore, it is often used in combination with other cryptographic techniques to enhance security.