# Symmetric and Asymmetric Encryption

Subject: Tech & Engineering 5 1392 6 min Master

## Introduction

Data encryption on the Internet is a common practice that allows users to transmit and store data securely. Encryption is required by many different functions and applications, from paying for purchases on the Internet to using gadgets such equipment as smart electrical appliances or smart homes. For this reason, the challenge for developers is to create encryption algorithms and methods that are easy to apply for users but difficult to break.

The most common of these methods are symmetric and asymmetric encryption, based on the use of complex keys and mathematical calculations to convert plain text into a cipher and back. However, both of these methods have their advantages and disadvantages that affect their application. Therefore, this article will study the main characteristics and differences between symmetric and asymmetric encryption to determine their benefits and security of use.

## Characteristics of Symmetric and Asymmetric Encryption

Data cryptography is a necessary and integral part of modern Internet technologies. Encryption ensures the privacy and security of information even when using unsecured networks and channels and makes it more difficult to steal data. This approach is essential for personal correspondence, online shopping, and the Internet of Things. Two cryptography methods used today to encrypt Internet data and conduct transactions are symmetric and asymmetric encryption.

Symmetric encryption is a technique that was first applied for Internet transactions and data transmission. This method has become the basis for the commercial application of cryptography in the world. The principle of symmetric encryption is based on the fact that the recipient and the sender share the same private key, which is used to encrypt and decrypt the message (Santoso et al., 2018). In other words, the sender enters the data and sends them to the recipient and by using the private secret key, and the recipient sees the plain text by applying the same key. At the same time, in the process of sending the message in the channel, the data remains safe. Nevertheless, the sender and receiver must have a secure network to exchange the private key.

Symmetric cryptography uses two types of encryption such as block cipher and stream cipher. Block cipher means that the data is formed into blocks of a certain length and size, and the stream cipher breaks the data into bits to encrypt and decrypt the information (Santoso et al., 2018). Data Encryption Standard (DES) was one of the earliest symmetric encryption systems; however, more sophisticated methods such as BlowFish, Triple Data Encryption Standard (3DES), and Advanced Encryption Standard (AES) were also developed after it was broken. Consequently, the history of symmetric encryption breaking demonstrates that although it is generally secure and complex, it has vulnerabilities that allow data to be stolen.

Asymmetric encoding was developed as a more reliable analog of the symmetric model. This encryption is based on two types of keys, public and private, which are used to encrypt or decrypt data (Santoso et al., 2018; Sujatha et al., 2016). The sender must enter the public key to encrypt and send the message, and the recipient must enter the private key to receive the decrypted text. At the same time, the recipient does not share the private key and keeps it secret, which makes it impossible for other people to decrypt the data. Hence, this process has the steps of key generation, distribution, encoding, and decryption.

Moreover, although the public key is not secret, it gives only a negligible chance of breaking the private key. The most famous systems are Rivest Shamir Adleman (RSA), Digital Signature Algorithm (DSA), Elliptic Curve Cryptography (ECC), Diffie Hellman, and Elgamal algorithms (Sujatha et al., 2016). Thus, this approach is the most secure and is often used on the Internet for information exchange and transactions.

## Differences Between Symmetric and Asymmetric Encryption

It is generally accepted that the main difference between the two encryption methods is that asymmetric algorithms are more complex and confidential. Therefore, the advantage asymmetric system is that it is more secure because it is more difficult to break due to the private key’s confidentiality. However, at the same time, these algorithms take more time to encrypt and decrypt (Santoso et al., 2018).

Simultaneously, the main disadvantage of symmetric models, in this case, is that they require a secure channel to transmit the secret code. Nevertheless, evaluation of such parameters as the entropy level and the Avalanche effect shows that the symmetric Blowfish and AES algorithms are more secure than RSA (Patil et al., 2016). However, while the asymmetric RSA takes more encryption and decryption time and memory, AES needs more bits and the highest bandwidth for transmission (Patil et al., 2016). In addition, symmetric keys are required per user pair, so multi-user sharing requires multiple keys (Sujatha et al., 2016). Consequently, each method has its advantages and disadvantages for convenience of use and safety, making them the most appropriate for different devices and areas of application.

## Security of Symmetric and Asymmetric Encryption

Comparing the two methods of encrypting data demonstrates that each has its security flaws. These disadvantages are associated with both the general principle of creating algorithms and their specific features. The main disadvantage of symmetric encryption is that its algorithms use a single private key that is shared by multiple users.

Therefore, these users need to find a secure channel to obtain their private key. At the same time, although asymmetric keys are often considered more reliable, some algorithms are inferior in their properties to symmetric ones. These properties make these algorithms more vulnerable than symmetric ones to breaking and data theft or corruption. However, since modern technologies make it almost impossible to break an asymmetric or symmetric cipher, asymmetric type of encryption is more secure due to applying of several keys.

Symmetric encryption has a significant disadvantage due to the need to share the private key that each pair of users has. Moreover, the more users, the more keys are needed, which ensures confidentiality but not the data’s authenticity (Sujatha et al., 2016). Consequently, the likelihood of a key leak increases, making encryption less secure. At the same time, asymmetric encryption keeps the private key safe because it does not need to be shared to exchange messages. This feature and the use of complex mathematical algorithms provide higher data security.

However, analysis of specific algorithms demonstrates that breaking asymmetric keys can be simpler than symmetric ciphers. For example, Patil et al. (2016) noted that the symmetric AES algorithm has a higher Avalanche effect than the asymmetric RSA. This indicator shows the degree of information confusion that makes it difficult to break the code. In addition, the symmetric Blowfish algorithm has the highest entropy, or randomness of information in an encrypted message, making it more secure against guessing attacks (Patil et al., 2016).

Nevertheless, since asymmetric encryption uses complex mathematical calculations, the probability of breaking remains low due to the need to change billions of combinations that do not have a basis for guessing. Thus, these findings demonstrate that asymmetric encryption can be less secure in terms of breaking, although symmetric keys are insecure due to the need to share them. Therefore, as long as there is no technology to match millions in combinations per second randomly, asymmetric encryption is more secure because there is no need to share the private key.

## Conclusion

Therefore, the analysis demonstrates that symmetric and asymmetric encryption have similarities and differences that bring advantages and disadvantages to their application. A common feature is the use of a key, which encrypts the message and makes it nearly impossible to break due to the complex mathematical calculations of computer programs. This approach allows users not to worry about the safety of data if they keep the private key secret. However, applying a shared private key by a pair of users and transmitting it in symmetric encryption is a significant disadvantage of this method, since the probability of the key getting to attackers increases.

This disadvantage is absent in asymmetric encryption because the private key is secret and confidential, but more complex algorithms make this method less convenient, capacious, and fast. At the same time, in some cases, breaking the asymmetric encryption can be simpler than symmetric one. However, until modern technologies have reached a new development level, random guessing of a private key is almost impossible, which makes asymmetric encryption the most secure method of protecting data.

## References

Patil, P., Narayankar, P., Narayan D.G., & Meena S.M. (2016). A comprehensive evaluation of cryptographic algorithms: DES, 3DES, AES, RSA and Blowfish. Procedia Computer Science, 78, 617–624. Web.

Santoso, P. P., Rilvani, E., Trisnawan, A. B., Adiyarta, K., Napitupulu, D., Sutabri, T., & Rahim, R. (2018). Systematic literature review: Comparison study of symmetric key and asymmetric key algorithm. IOP Conference Series: Materials Science and Engineering, 420, 1-6. Web.

Sujatha, K., Rao, P. V. N., Rao, A. A., & Rajesh, L. V. (2016). Renowned information security algorithms: A comparative study. International Journal of Engineering Research & Technology (IJERT), 5(2), 216-224. Web.