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Global Accelerated Learning • Est. 1999
Glossary Term Cipher Block Chaining (CBC)

Training Camp • Cybersecurity Glossary

What is Cipher Block Chaining (CBC)?

Cipher Block Chaining CBC is a block cipher mode chaining each block with the prior ciphertext and an IV; it lacks integrity and is prone to padding-oracle attacks.

Glossary > Cryptography & PKI > Cipher Block Chaining (CBC)

Understanding Cipher Block Chaining (CBC)

Cipher Block Chaining (CBC) is a block cipher mode of operation in which each plaintext block is XORed with the previous ciphertext block before encryption, so identical plaintext blocks produce different ciphertext and a random initialization vector is required for the first block. CBC provides confidentiality but not integrity or authentication on its own, and naive implementations are vulnerable to padding-oracle attacks such as those behind POODLE. Modern practice favors authenticated encryption modes like GCM, and CBC must be paired with a separate MAC when used.

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