[continued from previous message]

* Title: Reducing the computational complexity of fuzzy identity-based encryption from lattice
* Authors: Sedigheh Khajouei-Nejad, Hamid Haj Seyyed Javadi, Sam Jabbehdari, Seyed Mohammad Hossein Moattar
* [Permalink](https://eprint.iacr.org/2024/016)
* [Download](https://eprint.iacr.org/2024/016.pdf)

### Abstract

In order to provide access control on encrypted data, Attribute-based encryption (ABE) defines each user using a set of attributes. Fuzzy identity-based encryption (FIBE) is a variant of ABE that allows for a threshold access structure for users. To
address the potential threat posed by future quantum computers, this paper presents a post-quantum fuzzy IBE scheme based on lattices. However, current lattice-based ABE schemes face challenges related to computational complexity and the length of
ciphertext and keys. This paper aims to improve the performance of an existing fuzzy IBE scheme by reducing key length and computational complexity during the encryption phase. While negative attributes are not utilized in our scheme, we prove its
security under the learning with error (LWE) hard problem assumption in the selective security model. These improvements have significant implications for the field of ABE.



## 2024/17

* Title: PT-symmetric mapping of three states and its implementation on a cloud quantum processor
* Authors: Yaroslav Balytskyi, Yevgen Kotukh, Gennady Khalimov, Sang-Yoon Chang * [Permalink](https://eprint.iacr.org/2024/017)
* [Download](https://eprint.iacr.org/2024/017.pdf)

### Abstract

We develop a new PT-symmetric approach for mapping three pure qubit states, implement it by the dilation method, and demonstrate it with a superconducting quantum processor provided by the IBM Quantum Experience. We derive exact formulas for the
population of the post-selected PT-symmetric subspace and show consistency with the Hermitian case, conservation of average projections on reference vectors, and Quantum Fisher Information. When used for discrimination of N = 2 pure states, our algorithm
gives an equivalent result to the conventional unambiguous
quantum state discrimination. For N = 3 states, our approach provides novel properties unavailable in the conventional Hermitian case and can transform an arbitrary set of three quantum states into another arbitrary set of three states at the cost of
introducing an inconclusive result. For the QKD three-state protocol, our algorithm has the same error rate as the conventional minimum error, maximum confidence, and maximum mutual information strategies. The proposed method surpasses its Hermitian
counterparts in quantum sensing using non-MSE metrics, providing an advantage for precise estimations within specific data space regions and improved robustness to
outliers. Applied to quantum database search, our approach yields a notable decrease in circuit depth in comparison to traditional Grover’s search algorithm while maintaining the same average number of oracle calls, thereby offering significant
advantages for NISQ computers. Additionally, the versatility of our method can be valuable for the discrimination of highly non-symmetric quantum states, and quantum error correction. Our work unlocks new doors for applying PT -symmetry in quantum
communication, computing, and cryptography.

--- SoupGate-Win32 v1.05
* Origin: fsxNet Usenet Gateway (21:1/5)