TY - GEN

T1 - Shannon impossibility, revisited

AU - Dodis, Yevgeniy

N1 - Copyright:
Copyright 2012 Elsevier B.V., All rights reserved.

PY - 2012

Y1 - 2012

N2 - In this note we revisit the famous result of Shannon [Sha49] stating that any encryption scheme with perfect security against computationally unbounded attackers must have a secret key as long as the message. This result motivated the introduction of modern encryption schemes, which are secure only against a computationally bounded attacker, and allow some small (negligible) advantage to such an attacker. It is a well known folklore that both such relaxations - limiting the power of the attacker and allowing for some small advantage - are necessary to overcome Shannon's result. To our surprise, we could not find a clean and well documented proof of this folklore belief. (In fact, two proofs are required, each showing that only one of the two relaxations above is not sufficient.) Most proofs we saw either made some limiting assumptions (e.g., encryption is deterministic), or proved a much more complicated statement (e.g., beating Shannon's bound implies the existence of one-way functions [IL89].)

AB - In this note we revisit the famous result of Shannon [Sha49] stating that any encryption scheme with perfect security against computationally unbounded attackers must have a secret key as long as the message. This result motivated the introduction of modern encryption schemes, which are secure only against a computationally bounded attacker, and allow some small (negligible) advantage to such an attacker. It is a well known folklore that both such relaxations - limiting the power of the attacker and allowing for some small advantage - are necessary to overcome Shannon's result. To our surprise, we could not find a clean and well documented proof of this folklore belief. (In fact, two proofs are required, each showing that only one of the two relaxations above is not sufficient.) Most proofs we saw either made some limiting assumptions (e.g., encryption is deterministic), or proved a much more complicated statement (e.g., beating Shannon's bound implies the existence of one-way functions [IL89].)

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U2 - 10.1007/978-3-642-32284-6_6

DO - 10.1007/978-3-642-32284-6_6

M3 - Conference contribution

AN - SCOPUS:84865034944

SN - 9783642322839

T3 - Lecture Notes in Computer Science (including subseries Lecture Notes in Artificial Intelligence and Lecture Notes in Bioinformatics)

SP - 100

EP - 110

BT - Information Theoretic Security - 6th International Conference, ICITS 2012, Proceedings

T2 - 6th International Conference on Information Theoretic Security, ICITS 2012

Y2 - 15 August 2012 through 17 August 2012

ER -