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CEH - Cryptography - Cryptanalysis
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You are a security consultant investigating a breach at a cryptocurrency exchange. The attackers successfully accessed encrypted wallet keys stored in a database. Forensic analysis reveals that the encryption algorithm used was AES-256 in CBC mode, but the same initialization vector (IV) was reused for encrypting all wallet keys. Additionally, you discover that parts of the plaintext structure of the wallet keys follow a consistent format. What cryptanalytic attack would be most effective in this scenario?
a.
Chosen-ciphertext attack exploiting padding oracle vulnerabilities in the CBC implementation
b.
Known-plaintext attack combined with IV reuse exploitation
c.
Side-channel timing attack measuring the execution time of encryption operations
d.
Differential fault analysis targeting the key schedule of AES-256
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