2023年2月11日 · In CBC mode, we need a random Initialization Vector the size of a block, chosen randomly by the encrypting side at start of encryption of each message, and transmitted in clear to the receiving side (usually as the first block of ciphertext). We'll assume the IV is, in hexadecimal:

2017年6月26日 · That's where the mode of operations, such as CBC, come into play. Modes of operations are there to allow you to encrypt more data than the blocksize of your symmetric blockcipher. But since those modes of operation are still using the underlying blockcipher to encrypt data, it means that they can only encrypt a multiple of the blocksize. So, if ...

2021年7月24日 · In CBC mode, you encrypt a block of data by taking the current plaintext block and exclusive-oring that wth the previous ciphertext block (or IV), and then sending the result of that through the block cipher; the output of the block cipher is the ciphertext block. GCM mode provides both privacy (encryption) and integrity.

2016年11月30日 · With CBC, if you are missing a few blocks in the sequence encryption becomes impossible. However, there is one downside to CBC – ECB naturally supports operation in parallel since each block can be encrypted independently of the next. However, with CBC this is harder, since you have to wait on each block.

The same applies to the encrypt-and-authenticate method used in SSH. On the positive side we show that the authenticate-then-encrypt method is secure if the encryption method in use is either CBC mode (with an underlying secure block cipher) or a stream cipher (that xor the data with a random or pseudorandom pad). Thus, while we show the ...

2022年7月28日 · At least in the context of PKCS#5 (which is commonly seen through the encryption of PEM files), DES-EDE3-CBC is Triple DES with three keys, used in CBC mode, with unspecified padding. Yes, “EDE” means encrypt-decrypt-encrypt for encryption (and decrypt-encrypt-decrypt for decryption).

CBC is a block cipher mode of operation, not a cipher. It can work basically with any block cipher - the choice of the block cipher itself is independent (to a large extent) from the choice of the mode of operation. Examples of well known block ciphers include AES, …

$\begingroup$ @Thomas: no, you cannot generate the second picture from the third. If you were thinking about somehow undoing the xor that's in CBC mode, remember that you do the xor and then you encrypt with the block cipher; that means, to undo the xor, you would need to decrypt first, and you can't do that unless you have the key. $\endgroup$

2022年9月10日 · "AES-CBC mode to encrypt `0's to generate blocks of the one-time pad and then use that one-time pad stream to encrypt plain text through XOR" is effectively AES-OFB. It's fine for confidentiality, and fine if we disregard implementation issues and that it provides even less insurance on integrity than AES-CBC.

2016年2月9日 · I know reusing keys is a bad idea, especially for CBC and CBC-MAC, but the example for why on Wikipedia seemed to use encrypt-and-MAC. It seems obvious that the last block of encryption will be equal to the MAC when used in this way.