Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Attacks on practical quantum key distribution systems (and how to
  prevent them)   With the emergence of an information society, the idea of protecting
sensitive data is steadily gaining importance. Conventional encryption methods
may not be sufficient to guarantee data protection in the future. Quantum key
distribution (QKD) is an emerging technology that exploits fundamental physical
properties to guarantee perfect security in theory. However, it is not easy to
ensure in practice that the implementations of QKD systems are exactly in line
with the theoretical specifications. Such theory-practice deviations can open
loopholes and compromise the security. Several of such loopholes have been
discovered and investigated in the last decade. These activities have motivated
the proposal and implementation of appropriate countermeasures, thereby
preventing future attacks and enhancing the practical security of QKD. This
article introduces the so-called field of quantum hacking by summarizing a
variety of attacks and their prevention mechanisms.

23
The categories of this paper are: solv-int
4
The categories of this paper are: cond-mat
26
The categories of this paper are: bayes-an
28
The categories of this paper are: alg-geom
15
The categories of this paper are: nucl-ex
17
The categories of this paper are: q-fin
7
The categories of this paper are: hep-th
25
The categories of this paper are: patt-sol
3
The categories of this paper are: physics
24
The categories of this paper are: dg-ga
30
The categories of this paper are: q-alg
10
The categories of this paper are: q-bio
37
The categories of this paper are: supr-con
6
The categories of this paper are: astro-ph
36
The categories of this paper are: cmp-lg
11
The categories of this paper are: hep-lat