Paper 2024/1535
Relaxed Lattice-Based Programmable Hash Functions: New Efficient Adaptively Secure IBEs
Abstract
In this paper, we introduce the notion of relaxed lattice-based programmable hash function (RPHF), which is a novel variant of lattice-based programmable hash functions (PHFs). Lattice-based PHFs, together with preimage trapdoor functions (TDFs), have been widely utilized (implicitly or explicitly) in the construction of adaptively secure identity-based encryption (IBE) schemes. The preimage length and the output length of the underlying PHF and TDF together determine the user secret key and ciphertext lengths of the IBE schemes.
However, the current lattice-based PHF definition imposes the restriction that the preimage length of TDF in the IBE schemes cannot be too short, hindering the utilization of size-efficient NTRU TDF. To overcome this hurdle, RPHF relaxes the hash key distribution requirement in the definition of PHF from statistical indistinguishability to computational indistinguishability. This relaxation eliminates limitations on the preimage length of underlying TDFs in IBE, enabling the construction of IBEs from NTRU TDFs.
We introduce two instantiations of RPHF: the first produces a hash output length of
Metadata
- Available format(s)
-
PDF
- Category
- Public-key cryptography
- Publication info
- Preprint.
- Keywords
- Identity-Based EncryptionLattice-Based CryptographyNTRU lattice
- Contact author(s)
-
xing-ye lu @ polyu edu hk
jjfan @ cs hku hk
mhhau @ polyu edu hk - History
- 2024-10-04: approved
- 2024-10-01: received
- See all versions
- Short URL
- https://ia.cr/2024/1535
- License
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CC BY-NC
BibTeX
@misc{cryptoeprint:2024/1535, author = {Xingye Lu and Jingjing Fan and Man Ho AU}, title = {Relaxed Lattice-Based Programmable Hash Functions: New Efficient Adaptively Secure {IBEs}}, howpublished = {Cryptology {ePrint} Archive, Paper 2024/1535}, year = {2024}, url = {https://eprint.iacr.org/2024/1535} }