Authenticated Encryption with Associated Data (AEAD) Questions

Comprehensive understanding of AEAD modes (AES-GCM, ChaCha20-Poly1305, AES-SIV) and why authenticated encryption is essential rather than separate encryption and MAC. Common implementation pitfalls and how they compromise security. When different AEAD schemes are appropriate.

MediumTechnical

32 practiced

Compare AES-GCM and ChaCha20-Poly1305 for use in TLS on servers, mobile devices, and IoT. Discuss performance (with and without AES/ARM acceleration), battery/power impact, side-channel resistance, implementation complexity, and when one should be preferred over the other.

EasyTechnical

31 practiced

Summarize AES-SIV (Synthetic IV) mode and its misuse-resistant properties. Explain the S2V construction at a high level, why AES-SIV is deterministic and provides nonce-misuse resistance, and describe scenarios where deterministic encryption is acceptable or desirable (and where it's not).

HardTechnical

36 practiced

Analyze the security implications of truncating AEAD tags to 64 bits for a high-volume REST API that authenticates 10^7 requests per day. Calculate the expected false-acceptance rate over one year and discuss whether truncation is acceptable. Propose mitigations if truncation is necessary (such as rate limiting, additional MAC layers, or monitoring).

HardTechnical

30 practiced

Provide a detailed outline of an attack that recovers AES-GCM parameters or enables message forgery when IV reuse occurs. Include algebraic equations relating ciphertexts and GHASH outputs, indicate what unknowns must be solved (e.g., H), and quantify how many reused-IV samples and known plaintexts would make the attack practical.

EasyTechnical

37 practiced

Provide scenarios where AES-SIV is preferable to AES-GCM or ChaCha20-Poly1305. Include considerations such as storage/deduplication, deterministic encryption requirements, environments with poor randomness, long-term data-at-rest protection, and whether streaming or low-latency requirements influence your choice.

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