Which mode of AES allows parallel encryption of independent blocks but exposes patterns when identical plaintext blocks repeat?
A CISSP practice question covering Domain 3: Security Architecture and Engineering. Try answering before reading the explanation below.
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Why "ECB" is the right answer
ECB (Electronic Codebook) encrypts each block independently — repeated plaintext produces repeated ciphertext, leaking structure (the 'ECB penguin' image). CBC/GCM/CTR use IVs/nonces to break this. ECB should not be used for general data.
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