Paper 2015/248

Verifiably Encrypted Signatures with Short Keys based on the Decisional Linear Problem and Obfuscation for Encrypted VES

Ryo Nishimaki and Keita Xagawa

Abstract

Verifiably encrypted signatures (VES) are signatures encrypted by a public key of a trusted third party and we can verify their validity without decryption. This paper proposes a new VES scheme which is secure under the decisional linear (DLIN) assumption in the standard model. We also propose new obfuscators for encrypted signatures (ES) and encrypted VES (EVES) which are secure under the DLIN assumption. All previous efficient VES schemes in the standard model are either secure under standard assumptions (such as the computational Diffie-Hellman assumption) with large verification (or secret) keys or secure under \emph{(non-standard) dynamic $q$-type assumptions} (such as the $q$-strong Diffie-Hellman extraction assumption) with short verification keys. Our construction is the first efficient VES scheme with short verification (and secret) keys secure under \emph{a standard assumption (DLIN)}. As by-products of our VES scheme, we construct new obfuscators for ES/EVES based on our new VES scheme. They are more efficient than previous obfuscators with respect to the public key size. Previous obfuscators for EVES are secure under non-standard assumption and use zero-knowledge (ZK) proof systems and Fiat-Shamir heuristics to obtain non-interactive ZK, i.e., its security is considered in the random oracle model. Thus, our construction also has an advantage with respect to assumptions and security models. Our new obfuscator for ES is obtained from our new obfuscator for EVES.

Note: This is the IACR version.

Metadata
Available format(s)
PDF
Category
Cryptographic protocols
Publication info
Published by the IACR in Pkc 2013
Keywords
verifiably encrypted signatureobfuscationencrypted verifi- ably encrypted signaturedecisional linear assumption
Contact author(s)
nishimaki ryo @ lab ntt co jp
History
2015-03-19: received
Short URL
https://ia.cr/2015/248
License
Creative Commons Attribution
CC BY

BibTeX

@misc{cryptoeprint:2015/248,
      author = {Ryo Nishimaki and Keita Xagawa},
      title = {Verifiably Encrypted Signatures with Short Keys based on the Decisional Linear Problem and Obfuscation for Encrypted VES},
      howpublished = {Cryptology ePrint Archive, Paper 2015/248},
      year = {2015},
      note = {\url{https://eprint.iacr.org/2015/248}},
      url = {https://eprint.iacr.org/2015/248}
}
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