Key-Private Proxy Re-encryption under LWE
Proxy re-encryption (PRE) is a highly useful cryptographic primitive whereby Alice and Bob can endow a proxy with the capacity to change ciphertext recipients from Alice to Bob, without the proxy itself being able to decrypt, thereby providing delegation of decryption authority. Key-private PRE (KP-PRE) specifies an additional level of confidentiality, requiring pseudo-random proxy keys that leak no information on the identity of the delegators and delegatees.
In this paper, we propose a CPA-secure PK-PRE scheme in the standard model (which we then transform into a CCA-secure scheme in the random oracle model). Both schemes enjoy highly desirable properties such as uni-directionality and multi-hop delegation.
Unlike (the few) prior constructions of PRE and KP-PRE that typically rely on bilinear maps under ad hoc assumptions, security of our construction is based on the hardness of the standard Learning-With-Errors (LWE) problem, itself reducible from worst-case lattice hard problems that are conjectured immune to quantum cryptanalysis, or “post-quantum”.
Of independent interest, we further examine the practical hardness of the LWE assumption, using Kannan’s exhaustive search algorithm coupling with pruning techniques. This leads to state-of-the-art parameters not only for our scheme, but also for a number of other primitives based on LWE published the literature.
- Key-Private Proxy Re-encryption under LWE
- Book Title
- Progress in Cryptology – INDOCRYPT 2013
- Book Subtitle
- 14th International Conference on Cryptology in India, Mumbai, India, December 7-10, 2013. Proceedings
- pp 1-18
- Print ISBN
- Online ISBN
- Series Title
- Lecture Notes in Computer Science
- Series Volume
- Series ISSN
- Springer International Publishing
- Copyright Holder
- Springer International Publishing Switzerland
- Additional Links
- proxy re-encryption
- key privacy
- learning with errors
- chosen ciphertext security
- LWE practical hardness
- Industry Sectors
- eBook Packages
- Editor Affiliations
- 16. R.C. Bose Centre for Cryptology and Security, Indian Statistical Institute
- 17. EPFL - I&C - LASEC
- Author Affiliations
- 18. NICT, Japan
- 19. Queensland University of Technology, Australia
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