From the course: Symmetric Cryptography Essential Training

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Cipher block chaining (CBC)

Cipher block chaining (CBC)

From the course: Symmetric Cryptography Essential Training

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Cipher block chaining (CBC)

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- [Instructor] In cipher block chaining mode, usually called CBC, the ciphertext output from the previous block is XORed with the plaintext. Those of you paying close attention will notice that this is the mode I used when I demonstrated AES and DES from the command line. This mode is defined by the previous ciphertext block being included in the encryption of the current block. This is done simply by XORing the previous ciphertext with the current plaintext block. A few notes on CBC mode. It needs to have complete blocks to work properly, so some sort of padding will be necessary to ensure that this is the case. When you use cipher block chaining, you don't have the ability to encrypt the plaintext in parallel like ECB offered. You can, however, decrypt the ciphertext in parallel and that gives you the ability to have random read access to the ciphertext. You can decrypt different parts of the ciphertext without having to start from the beginning. When an error occurs in the…

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