Confidential Signatures and Deterministic Signcryption

Dent A, Fischlin M, Manulis M, Stam M, Schröder D (2009)

Publication Language: English

Publication Type: Conference contribution

Publication year: 2009

Book Volume: 2009

Pages Range: 588



Encrypt-and-sign, where one encrypts and signs a message in parallel, is usually not recommended for confidential message transmission. The reason is that the signature typically leaks information about the message. This motivates our investigation of confiden- tial signature schemes, which hide all information about (high-entropy) input messages. In this work we provide a formal treatment of confidentiality for such schemes and a comprehensive discussion of the relationship of different notions we propose. We give constructions meeting our notions, both in the random oracle model and the standard model. As part of this we show that full domain hash signatures achieve a weaker level of confidentiality than Fiat-Shamir signatures. We then revisit the connection of confidential signatures to sign- cryption schemes. We give formal security models for deterministic signcryption schemes for high-entropy and low-entropy messages, and prove encrypt-and-sign to be secure for confidential signature schemes and high-entropy messages. Finally, we show that one can derandomize any signcryption scheme in our model and obtain a secure deterministic scheme. 

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How to cite


Dent, A., Fischlin, M., Manulis, M., Stam, M., & Schröder, D. (2009). Confidential Signatures and Deterministic Signcryption. In Proceedings of the PKC Public-Key Cryptography (pp. 588).


Dent, Alexander, et al. "Confidential Signatures and Deterministic Signcryption." Proceedings of the PKC Public-Key Cryptography 2009. 588.

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