What Is Symmetric Encryption, How Does It Work & Why Use It?

Symmetric encryption (or “private key” encryption) is the process of using a single key to both encrypt and decrypt data. It’s called “private key” because the use of a single encryption key necessitates that the key is always kept private.

Symmetric encryption is a widely-used form of cryptography that provides organizations and users with a faster, more readily deployable form of security for large data sets.

Symmetric encryption is often used for high-volume data processing where speed, efficiency, and complexity are important. However, due to its nature as a single-key solution, it presents several security challenges when it comes to actually sharing encrypted data. For this reason, symmetric encryption is often combined with asymmetric encryption (which uses different keys for encryption and decryption) in many modern secure communication protocols.

How Does Symmetric Encryption Work?

Generally, encryption works by translating plain text into encoded (cipher) text using an algorithm and a secret key that is, theoretically, computationally infeasible to crack.

The general process of encryption works as follows:

  • Key Generation: A secret key is generated using advanced mathematical equations that is used to encode data. This key is shared between sender and receiver to maintain the obfuscation of the data.
  • Encryption: The encoding process uses complex algorithms and random environmental data (called “entropy”) to transform the original data is usually complex and involves multiple rounds of transformation to ensure the ciphertext is not easily decipherable without the key.
  • Decryption: Upon receiving the data, the recipient uses the same key to decode the data–essentially, reversing the process with the key serving as the information needed to “unlock” that data.

Additionally, symmetric encryption algorithms will usually come in one of two forms:

  • Stream Ciphers: Stream ciphers encrypt plaintext messages one bit at a time. They create an arbitrarily long keystream of bits, which is then combined with the plaintext bits one by one to produce the ciphertext.
  • Block Ciphers: Block ciphers take a chunk, or block, of data and transform it. It then works through the data set block by block. Some block ciphers will repeatedly encrypt blocks for added security.

How Does Symmetric Encryption Compare to Asymmetric Encryption?

As the name implies, symmetric encryption works through a sense of symmetry between both ends (encryption and decryption) of the process. Asymmetric encryption is the opposite–it uses a different key for each process..

Accordingly, the biggest challenge in symmetric encryption is the secure distribution of the key. Since the same key is used by all parties involved, it must be shared… which presents its own problems in terms of securing keys.

Conversely, asymmetric encryption doesn’t require this kind of sharing. Only one key (the public key) is shared, and it is only used for encoding data and cannot be used to compromise encrypted data.

What Are the Benefits of Symmetric Key Encryption?

This article has touched on the differences between symmetric and asymmetric encryption methods, differences that provide context for how symmetric methods benefit users and enterprises.

Some of the key bonuses of symmetric encryption include:

  • Speed: Symmetric algorithms are generally less computationally intensive as compared to their asymmetric counterparts. That makes them faster and less computationally intensive than asymmetric ones–perfect for encrypting large amounts of data.
  • Simplicity: Symmetric encryption involves only one key for both encryption and decryption, which can simplify key management, especially for contexts where key sharing isn’t a major concern.
  • Bandwidth: Data encoded with symmetric algorithms are generally smaller in size, which can help with bandwidth concerns if that is an issue.

It isn’t an “all-or-nothing” approach, however. Many systems or algorithms will combine both symmetric and asymmetric methods in a single process to leverage the strengths of both. combining symmetric and asymmetric encryption.

What Are Use Cases for Symmetric Key Encryption?

Generally speaking, there are a few cases where symmetric encryption is suitable. Namely, when a system needs to perform fast encryption, where there are large amounts of data to encrypt, and/or where key sharing isn’t a concern.

Within those criteria are several different use cases where symmetric encryption shines:

  • File and Disk Encryption: For encrypting files, databases, or entire drives, symmetric methods are the gold standard.
  • Bulk Data Encryption: In situations where large amounts of data need to be encrypted, symmetric encryption is typically the most practical method due to its speed and efficiency compared to asymmetric encryption.
  • Hybrid Algorithms: While asymmetric solutions solve some critical security issues, they are grossly inefficient when it comes to encrypting data efficiently. Thus hybrid systems will use asymmetric approaches to secure keys and verify user identities while using symmetric algorithms to actually encrypt data.

The most well-known application of a hybrid approach is Secure Socket Layers (SSL), currently renamed and refined as Transport Layer Security (TLS). These technologies are used as a “tunneling” method to create secure and persistent connection between machines. To accomplish this, SSL and TLS protocols actually use combinations of symmetric and asymmetric algorithms to strengthen security.

What Are Different Types of Symmetric Encryption?

There isn’t a limit on how many encryption algorithms exist. Some of the more popular, or at least well-known, symmetric algorithms around include:

  • Advanced Encryption Standard (AES): This is currently one of the most widely used symmetric encryption algorithms, supported for national security (by NIST) and industrial applications. There are several different complexities of AES (with 128-bit and 256-bit being the most common) that represent increasing levels of security.
  • Data Encryption Standard (DES): Primarily used decades ago, this symmetric algorithm has effectively been cracked and is no longer considered secure. It has been deprecated in favor of Triple DES or, in cases of federal or industrial encryption standards, AES.
  • Triple DES (3DES): This is an extension of the now-defunct DES algorithm that processes plaintext blocks three times for additional security, with a significant tradeoff with performance.
  • Blowfish and Twofish: These are block ciphers designed as alternatives to DES. Blowfish has a block size of 64 bits, while Twofish has a block size of 128 bits. Twofish was one of the finalists in the competition that selected AES.

Remember, no matter which algorithm or cipher type you use, the security of symmetric encryption relies heavily on keeping the encryption key secret and using a secure method to distribute the key when necessary.

1Kosmos BlockID and Encrypted Identity Management

Encryption is a critical part of identity management and authentication. With our private and permissioned blockchain, we leverage symmetric and asymmetric encryption methods to ensure that identity and authentication credentials (including biometrics) remain secure, that users are properly verified, and that decentralized devices can safely access the system.

With 1Kosmos, you get the following features:

  • Identity-Based Authentication: We push biometrics and authentication into a new “who you are” paradigm. BlockID uses biometrics to identify individuals, not devices, through credential triangulation and identity verification.
  • Cloud-Native Architecture: Flexible and scalable cloud architecture makes it simple to build applications using our standard API and SDK.
  • Identity Proofing: BlockID verifies identity anywhere, anytime and on any device with over 99% accuracy.
  • Privacy by Design: Embedding privacy into the design of our ecosystem is a core principle of 1Kosmos. We protect personally identifiable information in a distributed identity architecture and the encrypted data is only accessible by the user.
  • Private and Permissioned Blockchain: 1Kosmos protects personally identifiable information in a private and permissioned blockchain and encrypts digital identities and is only accessible by the user. The distributed properties ensure that there are no databases to breach or honeypots for hackers to target.
  • Interoperability: BlockID can readily integrate with existing infrastructure through its 50+ out of the box integrations or via API/SDK.
  • SIM Binding: The BlockID application uses SMS verification, identity proofing, and SIM card authentication to create solid, robust, and secure device authentication from any employee’s phone.

Make sure to sign up for the 1Kosmos newsletter. Also, read our whitepaper on Identity-Based Authentication.

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Meet the Author

Robert MacDonald

Vice President of Product Marketing

Robert is the Vice President of Product Marketing at 1Kosmos. He is a highly influential senior global marketer with more than 15 years of marketing experience in B2B and B2C software in the biometric authentication space. Prior to 1Kosmos, Rob managed product strategy and vision for the Identity and Access Management portfolio at Micro Focus, leading a team of product marketers to drive sales and support the channel. Earlier in his career he set the foundation for content planning, sales enablement and GTM activities for ForgeRock. He has also held senior marketing positions at Entrust, Dell, Quest and Corel Corporation.