Universal Proxy Re-Encryption

Nico Döttling; Ryo Nishimaki

Paper 2018/840

Universal Proxy Re-Encryption

Nico Döttling and Ryo Nishimaki

Abstract

We put forward the notion of universal proxy re-encryption (UPRE). A UPRE scheme enables a proxy to convert a ciphertext under a (delegator) public key of any existing public-key encryption (PKE) scheme into another ciphertext under a (delegatee) public key of any existing PKE scheme (possibly different from the delegator one). The proxy has a re-encryption key generated from the delegator's secret key and the delegatee public key. Thus UPRE generalizes proxy re-encryption by supporting arbitrary PKE schemes and allowing to convert ciphertexts into ones of possibly different PKE schemes. In this work, we - provide syntax and definitions for both UPRE and a variant we call relaxed UPRE. The relaxed variant means that decryption algorithms for re-encrypted ciphertexts are slightly modified but still only use the original delegatee secret keys for decryption. - construct a UPRE based on probabilistic indistinguishability obfuscation (PIO). It allows us to re-encrypt ciphertexts polynomially many times. - construct relaxed UPRE from garbled circuits (GCs). We provide two variants of this construction, one which allows us to re-encrypt ciphertexts polynomially many times, and a second one which satisfies a stronger security requirement but only allows us to re-encrypt ciphertexts a constant number of times.

Note: Full version.

Metadata

Available format(s): PDF
Category: Public-key cryptography
Publication info: A major revision of an IACR publication in PKC 2021
Keywords: universal proxy re-encryption proxy re-encryption public-key encryption secret sharing
Contact author(s): ryo nishimaki @ gmail com
nico doettling @ gmail com
History: 2021-03-02: last of 5 revisions; 2018-09-14: received; See all versions
Short URL: https://ia.cr/2018/840
License: CC BY

BibTeX

@misc{cryptoeprint:2018/840,
      author = {Nico Döttling and Ryo Nishimaki},
      title = {Universal Proxy Re-Encryption},
      howpublished = {Cryptology {ePrint} Archive, Paper 2018/840},
      year = {2018},
      url = {https://eprint.iacr.org/2018/840}
}