# The Dichotomy of Neural Networks and Cryptography: War and Peace
## 1 Introduction  
In recent years, artificial neural networks (ANNs), simply referred to as neural networks (NNs) have been of great interest to the research community. They consist of layered networks of nodes meant to mimic a human brain, where the nodes represent biological neurons and the connections between them represent the synapses. Neural computing, as technology and a field of research has a wide ecosystem. It is in close interaction with many scientific and technological fields. NNs support a range of technological fields including medical technology [1] as well as image processing [2], cloud computing [3], aerospace technology [4], meteorology [5], and especially in security-related technologies [6, 7]. Moreover, several technologies and sciences such as chaos theory [8], frequency-domain transforms [9], genetic algorithms [10] and Digital Signal Processing (DSP) [1] are supporting neural networks as enablers.  
In this paper, we focus on the intersection of neural computing with cryptography. Cryptography is the study of mathematical techniques as a means of securing data communication and storage. Like the case of neural computing, cryptography has a broad ecosystem consisting of different scientific and technological fields. It supports a variety of technologies including Internet of Things (IoT) [11], cloud computing [12], Fog computing [13], etc. [14]. It also serves to security-related scenarios such as information hiding [15], authentication [16, 17], privacy [18], etc. Furthermore, cryptography is supported by a variety of enabling technologies and sciences including radix \(2^{n}\)[19] and modular arithmetics [20], quantum computing [21, 22], coding and information theory [23, 24], Very Large Scale Integration [25], chaos theory [26], and error management techniques [27] are used to support cryptography.  
Neural computing and cryptography frequently appear in the ecosystems of each other. They come together, in war and peace, in many ways; NNs can play adversarial roles against cryptosystems while they can support and be supported by cryptography at the same time. This tight interaction forms a dichotomy. Figure 1 illustrates the two sides of this war-and-peace dichotomy.  
In Figure 1, the two bears facing each other represent the war or the adversarial role of NNs in breaking cryptographic systems. The teddy bear represents the peaceful give and take between the two technologies including the use of cryptography to secure NNs or the use of NNs in order to improve cryptosystems.  
A comprehensive survey on the war-and-peace dichotomy shown in Figure 1 can pave the way for future research. In this paper, we first summarize some existing relevant surveys. We highlight the shortcomings of these surveys to motivate this research. We will then discuss the current state of the war; the ways in which NNs are being used to break cryptogrphic systems. We will then study the state-of-the-art in the peace side; how the two technologies work in concert with each other, cryptography providing confidentiality and privacy guarantees for NNs, and NNs adding to the functionality and the security of cryptographic systems. Lastly, we will discuss how quantum computing might fit into the future of this dichotomy. We briefly discuss what the future may hold for the war-and-peace dichotomy under the impact of quantum computing.