Lecture Notes in Computer Science on Advances in Cryptology-EUROCRYPT'88
Random oracles are practical: a paradigm for designing efficient protocols
CCS '93 Proceedings of the 1st ACM conference on Computer and communications security
The random oracle methodology, revisited (preliminary version)
STOC '98 Proceedings of the thirtieth annual ACM symposium on Theory of computing
The Oracle Diffie-Hellman Assumptions and an Analysis of DHIES
CT-RSA 2001 Proceedings of the 2001 Conference on Topics in Cryptology: The Cryptographer's Track at RSA
On the Exact Security of Full Domain Hash
CRYPTO '00 Proceedings of the 20th Annual International Cryptology Conference on Advances in Cryptology
Separating Random Oracle Proofs from Complexity Theoretic Proofs: The Non-committing Encryption Case
CRYPTO '02 Proceedings of the 22nd Annual International Cryptology Conference on Advances in Cryptology
On the Existence of 3-Round Zero-Knowledge Protocols
CRYPTO '98 Proceedings of the 18th Annual International Cryptology Conference on Advances in Cryptology
On the (In)security of the Fiat-Shamir Paradigm
FOCS '03 Proceedings of the 44th Annual IEEE Symposium on Foundations of Computer Science
Short Signatures from the Weil Pairing
Journal of Cryptology
Leaky Random Oracle (Extended Abstract)
ProvSec '08 Proceedings of the 2nd International Conference on Provable Security
EUROCRYPT '09 Proceedings of the 28th Annual International Conference on Advances in Cryptology: the Theory and Applications of Cryptographic Techniques
The Twin Diffie–Hellman Problem and Applications
Journal of Cryptology
How to Confirm Cryptosystems Security: The Original Merkle-Damgård Is Still Alive!
ASIACRYPT '09 Proceedings of the 15th International Conference on the Theory and Application of Cryptology and Information Security: Advances in Cryptology
The exact security of digital signatures-how to sign with RSA and Rabin
EUROCRYPT'96 Proceedings of the 15th annual international conference on Theory and application of cryptographic techniques
Instantiability of RSA-OAEP under chosen-plaintext attack
CRYPTO'10 Proceedings of the 30th annual conference on Advances in cryptology
ASIACRYPT'06 Proceedings of the 12th international conference on Theory and Application of Cryptology and Information Security
Analysis of random oracle instantiation scenarios for OAEP and other practical schemes
CRYPTO'05 Proceedings of the 25th annual international conference on Advances in Cryptology
On the generic insecurity of the full domain hash
CRYPTO'05 Proceedings of the 25th annual international conference on Advances in Cryptology
| Hi-index | 0.01 |
We discuss a reduction notion relating the random oracles in two cryptographic schemes A and B. Basically, the random oracle of scheme B reduces to the one of scheme A if any hash function instantiation of the random oracle (possibly still oracle based) which makes A secure also makes B secure. In a sense, instantiating the random oracle in scheme B is thus not more demanding than the one for scheme A. If, in addition, the standard cryptographic assumptions for scheme B are implied by the ones for scheme A, we can conclude that scheme B actually relies on weaker assumptions. Technically, such a conclusion cannot be made given only individual proofs in the random oracle model for each scheme. The notion of randomoracle reducibility immediately allows to transfer an uninstantiability result from an uninstantiable scheme B to a scheme A to which the random oracle reduces. We are nonetheless mainly interested in the other direction as a mean to establish hierarchically ordered random-oracle based schemes in terms of security assumptions. As a positive example, we consider the twinDiffie-Hellman (DH) encryption scheme of Cash et al. (Journal of Cryptology, 2009), which has been shown to be secure under the DH assumption in the random oracle scheme. It thus appears to improve over the related hashed ElGamal encryption scheme which relies on the random oracle model and the strong DH assumption where the adversary also gets access to a decisional DH oracle. As explained above, we complement this believe by showing that the random oracle in the twin DH scheme actually reduces to the one of the hashed ElGamal encryption scheme. We finally discuss further random oracle reductions between common signature schemes like GQ, PSS, and FDH.