Which of the following modes does not implement chaining?
9. Which of the following modes does not implement chaining or “dependency on previous stage computations”? Explanation: Only CTR and ECB do not implement chaining.
What are four different block cipher modes?
The block cipher modes ECB, CBC, OFB, CFB, CTR, and XTS provide confidentiality, but they do not protect against accidental modification or malicious tampering. Modification or tampering can be detected with a separate message authentication code such as CBC-MAC, or a digital signature.
Is it possible to do plaintext block chaining?
Plaintext block chaining is also possible. Using our fast 32-bit AES as a model, we can implement CBC mode as follows. This code performs the CBC updates on a byte basis. In practice, it’s faster and mostly portable to perform the XORs as whole words at once.
How does the propagating block chaining mode work?
The propagating cipher block chaining or plaintext cipher-block chaining mode was designed to cause small changes in the ciphertext to propagate indefinitely when decrypting, as well as when encrypting. In PCBC mode, each block of plaintext is XORed with both the previous plaintext block and the previous ciphertext block before being encrypted.
Are there any concerns with cipher block chaining?
One concern in feedback modes is synchronization after transmission errors. Cipher block chaining is self-synchronizing: a transmission error in one block will result in an error in that block and the following block, but will not affect subsequent blocks. Plaintext block chaining is also possible.
What is the mode of operation of a block cipher?
Block cipher modes operate on whole blocks and require that the last part of the data be padded to a full block if it is smaller than the current block size. There are, however, modes that do not require padding because they effectively use a block cipher as a stream cipher .