# Cryptography and Network Security

By: Kartik Agrawal

July 7, 2020

Cryptography is vital when we communicate with people remotely sitting in different places. Online communication should be done securely because communication channels are often unsecured. Examples of unsecured channels are public channels like telephone, internet, and email. The guarantee of secure communication is the fundamental objective of cryptography. To achieve this objective, we encrypt our messages to prevent someone other than the actual Receiver from getting the news; interception could modify or destroy the message. The Receiver, on the other hand, will decrypt the message using the key decided between the Sender and Receiver.

### SYMMETRIC VS ASYMMETRIC

The original message is plaintext, and after encryption, the output is ciphertext. The next challenge is how two parties would agree to the secret key. If we use public communication to decide the secret key, the third party can easily intercept it and decrypt it back to get the message (plain text). There are many encryption algorithms used by cryptographers. Decryption is the reverse of encryption, and the one who decrypts the cipher is known as a cryptanalyst. It is clear that cryptographers design the code, and cryptanalysts break the system. There are two types of encryption techniques, i.e., symmetric and asymmetric. Symmetric encryption is more suitable for a large amount of data is to be encrypted. One would make use of asymmetric encryption in case of Wireless security, processor security and file encryption, SSL/TLS protocol (website security), wi-fi security, mobile app encryption, VPN (a virtual private network), etc. Hybrid encryption is a combination of symmetric and asymmetric encryption. It is generally used in website security where one has to encrypt the data at high speed and maintain the authenticity of the user whose information is being encrypted.

### ENCRYPTION ALGORITHMS

While there are several cryptographic algorithms, each one starts with elementary mathematics like addition, subtraction, etc., followed by an XOR function and many other sophisticated methods, with symmetric and asymmetric keys changing every day. Some of the most popular encryption techniques are SHA (Secure Hash Algorithm), AES, 3DES (Triple Data Encryption Standard), DES, RSA Public Key Cryptosystem, and ECDSA (Elliptic Curve Digital Signature Algorithm). These algorithms are unique, having their particular advantages and drawbacks. It is highly beneficial to study all these algorithms, including their weaknesses and how to decrypt them. Over time, most of these algorithms can be decrypted, and decrypting these sophisticated algorithms is now a matter of seconds or sometimes much less.

### IMPLEMENTATION

We can implement cryptographic techniques using hardware or software. We can apply them to dedicated hardware or software installed on any general-purpose device. In software cryptographic techniques, security levels, characteristics of the operating system, and any other supported software are responsible for encryption and decryption. The dedicated resource will not have any dedicated memory location, so stealing and manipulation of data would be easy. Reverse engineering is possible in software implementation. On the other hand, using hardware is much faster, and we can securely store vital information. Reverse engineering is not possible, and it is difficult to access the public key. Firmware and firewalls are used to protect the information in hardware and software, respectively.

### FUTURE SCOPE

In the future, everything will be connected to a network. There will not be any gap between anything. Yes, this refers to the IoT infrastructure, and so will its diverse effect on the darknet. At that time, everything would be vulnerable. Cryptography and network security counter those vulnerabilities. Imagine a self-driving car without an encrypted key: it will become someone's car in minutes. Bitcoin is another emerging technology, and it, too, requires protection by cryptographic techniques, specifically AI-based encrypted blockchain. Encryption algorithms made by artificial intelligence is remarkable - the hash function is highly complex, and we do not know which hash function is used. Knowing what we know about AI, it will increase the complexity as the system become more exploitable.

Neural cryptography is the branch of cryptography in which cryptographers deal with the dynamic environment. Its output changes with the change in the background, even the inputs are the same. ANN (Artificial Neural Network) is a branch that deals with intelligent systems. ANN has a lot to explore in the field of cryptanalysis and offers a new approach for cryptanalysts to break the cryptographic algorithms used by neural networks. It has proven to be a more powerful technique to compute the plaintext out of the ciphertext generated. ANN works on the principle of mutual learning and stochastic behavior. It is advantageous in different aspects of cryptography. ANN uses mutual synchronization to find the inverse function of any encryption algorithm or public key for any cryptographic communication channel. Public key encryption has the advantage of short time and memory complexities. But by using ANN, it becomes a disadvantage for the same. At first, this approach was examined on a DES and gives out extraordinary results. In traditional cryptography, we use the Diffie- Hellman key exchange protocol. In contrast, in this neural cryptographic scheme, the neural key exchange protocol performs better and has the edge over traditional methods. Tree parity machine is the technique by which, if by chance, the cryptanalyst gets the public key, we are assured that he/she could not modify it.

### CONCLUSION

Information is the primary factor in determining whether a battle is won or lost. Everyone will fight for that data. Encryption is the only way to protect the data from rivals. Soon, everything will be vulnerable; everything will be accessible. The more complex our encryption algorithm is, the safer we are. In cybersecurity, cryptography plays a vital role. Almost every analyst knows cybersecurity and how to implement controls. The greatest impact will be cryptography and its application. The approach of cryptography and network security is going far beyond the human mind's computation limit, and it is what brings the thrill and curiosity to this topic.