International Association for Cryptologic Research

International Association
for Cryptologic Research


Paper: Custodian-Hiding Verifiable Encryption

Joseph K. Liu
Victor K. Wei
Duncan S. Wong
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Abstract: In a verifiable encryption, an asymmetrically encrypted ciphertext can be publicly verified to be decipherable by a designated receiver while maintaining the semantic security of the message \cite{AsokanShWa98,CamenischDa00,CamenischSh03}. In this paper, we introduce {\em Custodian-Hiding Verifiable Encryption}, where it can be publicly verified that there exists at least one custodian (user), out of a designated group of $n$ custodians (users), who can decrypt the message, while the semantic security of the message and the anonymity of the actual decryptor are maintained. Our scheme is proven secure in the random oracle model. We also introduce two extensions to decryption by a subset of more than one user.
  title={Custodian-Hiding Verifiable Encryption},
  booktitle={IACR Eprint archive},
  keywords={Verifiable Encryption, Publicly Verifiable, Anonymity},
  note={WISA 2004 12653 received 2 Feb 2004, last revised 22 Aug 2004},
  author={Joseph K. Liu and Victor K. Wei and Duncan S. Wong},