Ciphertext-auditable public key encryption

Satoshi Hada, Kouichi Sakurai

Research output: Chapter in Book/Report/Conference proceedingConference contribution

2 Citations (Scopus)


Loss of backup tapes containing personal information (PI) is a potential breach of privacy and encryption is the typical way to prevent the breach. This paper considers an attack scenario where an adversary who encrypts the PI for backup purpose tries to hide the plain PI in a valid-looking ciphertext without being detected. We show that the standard security notion IND-CCA2 does not capture such a scenario. For example, the Cramer-Shoup scheme is vulnerable to such an attack. To capture such a scenario, we define a new notion of "ciphertext-auditability" as a new property of public key encryption schemes (PKESs). It requires that, given a public key and a ciphertext, anyone should be able to verify whether the ciphertext was actually generated using the public key. Also, it requires that, given a public key and a plaintext, no adversary should be able to generate a valid-looking ciphertext so that the verification passes, but nevertheless the plaintext can be recovered from the ciphertext without the corresponding secret key. We propose a general construction of such PKESs based on standard cryptographic primitives in the random oracle model.

Original languageEnglish
Title of host publicationAdvances in Information and Computer Security - First International Workshop on Security, IWSEC 2006, Proceedings
PublisherSpringer Verlag
Number of pages14
ISBN (Print)3540476997, 9783540476993
Publication statusPublished - 2006
Event1st International Workshop on Security, IWSEC 2006 - Kyoto, Japan
Duration: Oct 23 2006Oct 24 2006

Publication series

NameLecture Notes in Computer Science (including subseries Lecture Notes in Artificial Intelligence and Lecture Notes in Bioinformatics)
Volume4266 LNCS
ISSN (Print)0302-9743
ISSN (Electronic)1611-3349


Other1st International Workshop on Security, IWSEC 2006

All Science Journal Classification (ASJC) codes

  • Theoretical Computer Science
  • General Computer Science


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