Paper 2024/798
Incompressible Functional Encryption
Abstract
Incompressible encryption (Dziembowski, Crypto'06; Guan, Wichs, Zhandry, Eurocrypt'22) protects from attackers that learn the entire decryption key, but cannot store the full ciphertext. In incompressible encryption, the attacker must try to compress a ciphertext within prespecified memory bound $S$ before receiving the secret key. In this work, we generalize the notion of incompressibility to functional encryption. In incompressible functional encryption, the adversary can corrupt nondistinguishing keys at any point, but receives the distinguishing keys only after compressing the ciphertext to within $S$ bits. An important efficiency measure for incompressible encryption is the ciphertextrate ( i.e., $\mathsf{rate} = \frac{m}{\mathsf{ct}}$). We give many new results for incompressible functional encryption for circuits, from minimal assumption of (nonincompressible) functional encryption, with 1. $\mathsf{ct}$rate$\frac{1}{2}$ and short secret keys, 2. $\mathsf{ct}$rate$1$ and large secret keys. Along the way, we also give a new incompressible attributebased encryption for circuits from standard assumptions, with $\mathsf{ct}$rate$\frac{1}{2}$ and short secret keys. Our results achieve optimal efficiency, as incompressible attributebased/functional encryption with $\mathsf{ct}$rate$1$ as well as short secret keys has strong barriers for provable security from standard assumptions. Moreover, our assumptions are minimal as incompressible attributebased/functional encryption are strictly stronger than their nonincompressible counterparts.
Metadata
 Available format(s)
 Category
 Publickey cryptography
 Publication info
 Preprint.
 Keywords
 incompressiblefunctionalencryptionattributebasedencryption
 Contact author(s)

rishab @ cs wisc edu
kvenkata @ iitd ac in
srmahesh1994 @ gmail com
amanverma1729 @ gmail com  History
 20241009: revised
 20240523: received
 See all versions
 Short URL
 https://ia.cr/2024/798
 License

CC BY
BibTeX
@misc{cryptoeprint:2024/798, author = {Rishab Goyal and Venkata Koppula and Mahesh Sreekumar Rajasree and Aman Verma}, title = {Incompressible Functional Encryption}, howpublished = {Cryptology {ePrint} Archive, Paper 2024/798}, year = {2024}, url = {https://eprint.iacr.org/2024/798} }