Paper 2024/1416

Circuit ABE with poly(depth, λ)-sized Ciphertexts and Keys from Lattices

Hoeteck Wee, NTT Research
Abstract

We present new lattice-based attribute-based encryption (ABE) and laconic function evaluation (LFE) schemes for circuits with *sublinear* ciphertext overhead. For depth $d$ circuits over $\ell$-bit inputs, we obtain * an ABE with ciphertext and secret key size $O(1)$; * a LFE with ciphertext size $\ell + O(1)$ and digest size $O(1)$; * an ABE with public key and ciphertext size $O(\ell^{2/3})$ and secret key size $O(1)$, where $O(\cdot)$ hides $\mbox{poly}(d,\lambda)$ factors. The first two results achieve almost optimal ciphertext and secret key / digest sizes, up to the $\mbox{poly}(d)$ dependencies. The security of our schemes relies on $\ell$-succinct LWE, a falsifiable assumption which is implied by evasive LWE. At the core of our results is a new technique for compressing LWE samples $\mathbf{s}(\mathbf{A}-\mathbf{x} \otimes \mathbf{G})$ as well as the matrix $\mathbf{A}$.

Metadata
Available format(s)
PDF
Category
Public-key cryptography
Publication info
A minor revision of an IACR publication in CRYPTO 2024
Contact author(s)
wee @ di ens fr
History
2024-09-11: approved
2024-09-10: received
See all versions
Short URL
https://ia.cr/2024/1416
License
Creative Commons Attribution
CC BY

BibTeX

@misc{cryptoeprint:2024/1416,
      author = {Hoeteck Wee},
      title = {Circuit {ABE} with poly(depth, λ)-sized Ciphertexts and Keys from Lattices},
      howpublished = {Cryptology {ePrint} Archive, Paper 2024/1416},
      year = {2024},
      url = {https://eprint.iacr.org/2024/1416}
}
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