



@article {2620,
	title = {Quantum Non-malleability and Authentication},
	journal = {In: Katz J., Shacham H. (eds) Advances in Cryptology {\textendash} CRYPTO 2017. Lecture Notes in Computer Science. Springer, Cham},
	volume = {10402},
	year = {2017},
	abstract = {<p>In encryption, non-malleability is a highly desirable property: it ensures that adversaries cannot manipulate the plaintext by acting on the ciphertext. In [6], Ambainis et al. gave a definition of non-malleability for the encryption of quantum data. In this work, we show that this definition is too weak, as it allows adversaries to \&ldquo;inject\&rdquo; plaintexts of their choice into the ciphertext. We give a new definition of quantum non-malleability which resolves this problem. Our definition is expressed in terms of entropic quantities, considers stronger adversaries, and does not assume secrecy. Rather, we prove that quantum non-malleability implies secrecy; this is in stark contrast to the classical setting, where the two properties are completely independent. For unitary schemes, our notion of non-malleability is equivalent to encryption with a two-design (and hence also to the definition of [6]).</p><p>Our techniques also yield new results regarding the closely-related task of quantum authentication. We show that \&ldquo;total authentication\&rdquo; (a notion recently proposed by Garg et al. [18]) can be satisfied with two-designs, a significant improvement over the eight-design construction of [18]. We also show that, under a mild adaptation of the rejection procedure, both total authentication and our notion of non-malleability yield quantum authentication as defined by Dupuis et al. [16].</p>},
	doi = {https://doi.org/10.1007/978-3-319-63715-0_11},
	author = {Gorjan Alagic and Christian Majenz}
}
