@inproceedings {43112,
	title = {Multi-Instance Secure Public-Key Encryption},
	journal = {PKC 2023, Part II},
	year = {2023},
	month = {05/2023},
	pages = {336-367},
	publisher = {Springer Nature Switzerland},
	address = {Cham},
	abstract = {Mass surveillance targets many users at the same time with the goal of learning as much as possible. Intuitively, breaking many users{\textquoteright} cryptography simultaneously should be at least as hard as that of only breaking a single one, but ideally security degradation is gradual: an adversary ought to work harder to break more. Bellare, Ristenpart and Tessaro (Crypto{\textquoteright}12) introduced the notion of multi-instance security to capture the related concept for password hashing with salts. Auerbach, Giacon and Kiltz (Eurocrypt{\textquoteright}20) motivated the study of public key encryption (PKE) in the multi-instance setting, yet their technical results are exclusively stated in terms of key encapsulation mechanisms (KEMs), leaving a considerable gap. We investigate the multi-instance security of public key encryption. Our contributions are twofold. Firstly, we define and compare possible security notions for multi-instance PKE, where we include PKE schemes whose correctness is not perfect. Secondly, we observe that, in general, a hybrid encryption scheme of a multi-instance secure KEM and an arbitrary data encapsulation mechanism (DEM) is unlikely to inherit the KEM{\textquoteright}s multi-instance security. Yet, we show how with a suitable information-theoretic DEM, and a computationally secure key derivation function if need be, inheritance is possible. As far as we are aware, ours is the first inheritance result in the challenging multi-bit scenario.},
	keywords = {Hybrid Encryption, Mass Surveillance, Multi-Instance Security, Property Inheritance},
	isbn = {978-3-031-31370-7},
	doi = {10.1007/978-3-031-31371-4_12},
	url = {https://doi.org/10.1007/978-3-031-31371-4_12},
	author = {Brunetta, Carlo and Heum, Hans and Stam, Martijn},
	editor = {Boldyreva, Alexandra and Kolesnikov, Vladimir}
}
@inproceedings {28253,
	title = {FASTA {\textendash} a stream cipher for fast FHE evaluation},
	journal = {Topics in Cryptology - CT-RSA 2022 - Cryptographers{\textquoteright} Track at the RSA Conference 2022},
	volume = {13161},
	year = {2022},
	pages = {451-483},
	publisher = { Springer},
	address = {Lecture Notes in Computer Science},
	abstract = {In this paper we propose Fasta, a stream cipher design optimised for implementation over popular fully homomorphic encryption schemes. A number of symmetric encryption ciphers have been recently proposed for FHE applications, e.g. the block cipher LowMC, and the stream ciphers Rasta (and variants), FLIP and Kreyvium. The main design criterion employed in these ciphers has typically been to minimise the multiplicative complexity of the algorithm. However, other aspects affecting their efficient evaluation over common FHE libraries are often overlooked, compromising their real-world performance. Whilst Fasta may also be considered as a variant of Rasta, it has its parameters and linear layer especially chosen to allow efficient implementation over the BGV scheme, particularly as implemented in the HElib library. This results in a speedup by a factor of 25 compared to the most efficient publicly available implementation of Rasta.\&nbsp; Fasta{\textquoteright}s target is BGV, as implemented in HElib. However the design ideas introduced in the cipher could also be potentially employed to achieve improvements in the homomorphic evaluation in other popular FHE schemes/libraries. We do consider such alternatives in this paper (e.g. BFV and BGVrns, as implemented in SEAL and PALISADE), but argue that, unlike BGVin HElib, it is more challenging to make use of their parallelism in a Rasta-like stream cipher design.},
	keywords = {Homomorphic Encryption, Hybrid Encryption, secret-key cryptography, Stream Ciphers},
	doi = {10.1007/978-3-030-95312-6_19},
	url = {https://link.springer.com/chapter/10.1007/978-3-030-95312-6_19},
	author = {Cid, Carlos and John Petter {Indr{\o}y} and Raddum, H{\r a}vard},
	editor = {Galbraith, Steven}
}
