Refine
Year of publication
- 2000 (3) (remove)
Document Type
- Preprint (3) (remove)
Language
- English (3)
Has Fulltext
- yes (3)
Is part of the Bibliography
- no (3) (remove)
Keywords
- Chinese Remainder Theorem (1)
- Closest Vector Problem (1)
- Commitment Scheme (1)
- Discrete Logarithm (1)
- Kongress (1)
- Kryptologie (1)
- Lattice Reduction (1)
- McEliece (1)
- Noticeable Probability (1)
- Online-Publikation (1)
Institute
- Informatik (3) (remove)
We present efficient non-malleable commitment schemes based on standard assumptions such as RSA and Discrete-Log, and under the condition that the network provides publicly available RSA or Discrete-Log parameters generated by a trusted party. Our protocols require only three rounds and a few modular exponentiations. We also discuss the difference between the notion of non-malleable commitment schemes used by Dolev, Dwork and Naor [DDN00] and the one given by Di Crescenzo, Ishai and Ostrovsky [DIO98].
Assuming a cryptographically strong cyclic group G of prime order q and a random hash function H, we show that ElGamal encryption with an added Schnorr signature is secure against the adaptive chosen ciphertext attack, in which an attacker can freely use a decryption oracle except for the target ciphertext. We also prove security against the novel one-more-decyption attack. Our security proofs are in a new model, corresponding to a combination of two previously introduced models, the Random Oracle model and the Generic model. The security extends to the distributed threshold version of the scheme. Moreover, we propose a very practical scheme for private information retrieval that is based on blind decryption of ElGamal ciphertexts.