Symmetric Encryption

1.1 Overview

In today’s digital era, there is always a threat of unauthorized access to sensitive data. Though privacy and security are must for all organizations, the most targeted industries are financial corporations and payment systems. A single data breach, on average, costs an organization around $3.7 million and the Cybersecurity Ventures estimates that 2021 is going to witness cybercrimes worth $6 trillion!

For safeguarding sensitive information, encryption holds great significance as it considerably mitigates the associated risks. For this reason, now symmetric encryption is present everywhere in the digital ecosystem.

This article delineates the details of symmetric encryption and throws light on the advantages and challenges.

1. About Symmetric Encryption
   • 1.1 Overview
   • 1.2 What is Symmetric Encryption?
   • 1.3 How Symmetric Encryption Works?
2. Symmetric Encryption Algorithms
   • 2.1 Data Encryption Standard
   • 2.2 Triple Data Encryption Standard
   • 2.3 Advanced Encryption Standard
3. Advantages of Symmetric Encryption
4. Disadvantages of Symmetric Encryption
5. Security of Symmetric Keys
6. Use Cases
   • 6.1 Banking and Payment Facilities
   • 6.2 Data at Rest
   • 6.3 HTTPS and Websites

1.2 What is Symmetric Encryption?

Simply stated, Symmetric Encryption is the technique in which the same key encrypts and decrypts the data sets or the messages transacted within various systems.

Such cryptographic techniques were initially used by governmental authorities to make contact with military heads. Now, to improve data security within computer systems, algorithm-based symmetric encryption is being used everywhere.

In symmetric encryption, both the sending and receiving units have a similar key, which is kept a secret.

1.3 How Symmetric Encryption Works?

In encryption, the algorithm transforms the data in a format which cannot be understood by anyone. A special & confidential key is required to decipher that data set into a readable format. As the intended recipient receives the ciphered data, the confidential key transforms it back to the readable format.

Three main steps involved in symmetric encryption are:

1. The sender uses an alpha-numeric string, termed as the encryption key, to cipher confidential data.
2. The ciphered message, termed as ‘ciphertext’ looks like random numbers whose real meaning can’t be understood.
3. The intended recipient has the same deciphering key that transforms the ciphertext into the previous format.

The secret keys used by the senders and the recipients might be a specially developed passcode or a special sequence developed by the random number generator which also decrypts them back.

There are two main types of symmetric encryption:

A. Block Encryption: In this, the set numbers of bits are ciphered in electronic data blocks with the help of a secret key. As the information is ciphered, the system stores data in the internal memory.

B. Stream Encryption: In this tactic, the data encryption directly streams in place of being stored in the system’s internal memory.

2. Symmetric Encryption Algorithms

The most well-known and the most commonly used algorithms for symmetric encryption are:

2.1 Data Encryption Standard

It is a block-type encryption tactic that ciphers data in 64-bit blocks and uses a single key available in any of the three sizes: 64, 128, 192-bit. DES is one of the earliest symmetric encryption algorithms but now it is considered to be insecure and obsolete.

2.2 Triple Data Encryption Standard

Unlike the DES, this tactic deploys two to three keys, enabling the algorithm to have multiple rounds of encryption and decryption processes. Triple Data Encryption Standard algorithm is much more secure than its predecessor- DES.

2.3 Advanced Encryption Standard

Now, one will find the advanced encryption standard algorithm being used at all places of the cyber world. With the key options of 128, 192, 256 bits this algorithm is much more efficient & secure than the previous ‘predecessors’. Though it is a block-type cipher tactic, it operates in the substitution-permutation network. Therefore it is much different than other algorithms which work on Feistel Ciphering.

Apart from these three most commonly used algorithms, other ones are:

IDEA (International Data Encryption Algorithm), Blowfish, RC4, RC5, RC6.

Out of them, RC4 is a stream cipher tactic.

3. Advantages of Symmetric Encryption

The main advantage of symmetric encryption over other ciphering techniques is its agility and efficiency for safeguarding a vast amount of sensitive data. The symmetric algorithms provide a greater degree of safety and the sheer simplicity is also a logical advantage since there is a lesser need for processing powers.

Furthermore, the protection level can be easily enhanced by increasing the length of the key. With every bit added to the key, the requirement of the forces to breach the security increases exponentially.

4. Disadvantages of Symmetric Encryption

The biggest and the most important challenge in symmetric encryption is the inherent problem in the transmission of the keys. As the same key is used for ciphering and deciphering the data sets, if the key is passed over to unauthorized malicious users, then the third parties can easily intercept the data sets. With a malicious user getting access to the key, the whole system data security comes into question.

So, for symmetric encryption to work, the sender and the intended user must know and have the keys secure with them. If anyone else has got the key then they can easily decrypt data and access them for any type of use. So there would be no point in such an encryption process where the keys are not safe.

5. Security of the Symmetric Keys

There are few considerations that specify the strength of encrypting keys. Major ones include:

1. Length of the key
2. Randomness of Generation
3. Time taken to decrypt back

6. Use Cases

Symmetric Encryptions have various use cases across varied industrial verticals. But major ones needing better security in terms of their data safety are:

6.1 Banking and Payment Card Facilities

These industries have a specific standard of security requirements- PCI DSS. This Payment Card Industry Data Security Standard is a set of 12 basic requirements that businesses and organizations in the domain must adhere to. In the PCI compliances, symmetric encryption is a vital component and directly correlates the protection of the data of at-rest cardholders.

6.2 Data at Rest

Data at rest is nothing but the state of all your data that is sitting idle on a server or any device. Being idle means it isn’t being transacted across a network over the internet.

Following are some common products/services that incorporate symmetric encryption to secure the backups:

Microsoft Azure: The leading cloud computing service platform Microsoft Azure uses symmetric encryption to cipher and decipher a lot of data sets very quickly.

Salesforce: Cloud-based customer relationship management service provider Salesforce uses Advanced Encryption System algorithm 256 bits to secure the data at rest.

G-Suite: Many of Google’s G-Suite services use in-transit encryption via HTTPS to secure your data.

CodeGuard: It is a website data backup tool that greatly helps in getting back the data in case of a failure or complete collapse. It also uses AES-256 encryption to secure all those backups.

6.3 HTTPS and Websites

Encryption for any active session is done via symmetric encryption and is an integral part of website security.