Failing Gracefully: Decryption Failures and the Fujisaki-Okamoto Transform
نویسندگان
چکیده
In known security reductions for the Fujisaki-Okamoto transformation, decryption failures are handled via a reduction solving rather unnatural task of finding failing plaintexts given private key, resulting in Grover search bound. Moreover, they require an implicit rejection mechanism invalid ciphertexts to achieve reasonable bound QROM. We present that has neither these deficiencies: introduce two games related failures, one capturing computationally hard using public key find failure, and statistically searching random oracle key-independent like, e.g., large randomness. As result, our bounds QROM tighter than previous ones with respect generic attacks: The attacker can only partially compute predicate, namely said failures. addition, entire works explicit-reject variant transformation improves significantly over all its reductions. Besides being more natural explicit reject is also relevant side channel attack resilience implicit-rejection variant. Along way, we prove several technical results characterizing preimage extraction certain tasks might be independent interest.
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ژورنال
عنوان ژورنال: Lecture Notes in Computer Science
سال: 2022
ISSN: ['1611-3349', '0302-9743']
DOI: https://doi.org/10.1007/978-3-031-22972-5_15