What is an Encryption Key? Types You Need to Know

By Tibor Moes / Updated: July 2023

What is an Encryption Key? Types You Need to Know

What is an Encryption Key?

Encryption is all around you. It is the scrambling and unscrambling of data. Its purpose is to make sure that unauthorized eyes can’t understand it.

The sender encrypts the data before sending it on its way. And the receiver decrypts the data after it has arrived. And for anyone in the middle, the data is unreadable.

But how can the sender and receiver make sure that they are the only ones able to encrypt and decrypt the data? That is where the encryption key comes in.

So, what is an encryption key?


  • An encryption key is a piece of data utilized in cryptography to transform plaintext into ciphertext (encryption) and vice versa (decryption). Its complexity defines the difficulty of the decryption process for unauthorized parties.

  • There are two types of encryption keys: Symmetric, where the same key is used for encryption and decryption, offering high speed but potential vulnerability if the key is exposed; and Asymmetric, involving a pair of keys – a public key for encryption and a private key for decryption, providing enhanced security at the cost of computational efficiency.

  • The strength of an encryption key is largely determined by its length, measured in bits. Longer keys offer greater security but require more processing power. Key management, involving generation, distribution, storage, and destruction of keys, is a critical aspect of information security.

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How Does an Encryption Key Work?

Before we explain encryption keys, let’s first discuss data encryption.

Data encryption is a process converts or transforms information into scrambled data to hide data from malicious actors. The message is automatically unscrambled for the intended recipient of the message. Various encryption algorithms are mathematically based and generally involve complex calculations.

There are several types of encryption modes, with each serving a particular purpose. The most well-known data encryption example of how your personal information is secured on Facebook or other social media sites. Other processes protect your cell phone password or hide credentials on a computer through PC or Mac keys.

Encryption keys are an integral part of data encryption. They add a unique element to this conversion process.

For instance, suppose you wanted to code the message “I like cats” using the word “hello.” Your encryption code could look something like this: NJHGUOCKIOP.

If you add another key, such as “flower,” to encrypt the same line, your new code may look like this: HGUODFKCLSHFLEL. The key length may also change.

The result of updating your encryption key is highly effective. It makes the string more random to minimize the risk of unauthorized access and optimize your data security.

Now that we’ve covered the basics of encryption keys, here’s an example that explains how they work when you want to access your protected data:

  1. Your request access to your encrypted message.

  2. The storage, file system, application, or database sends a request to retrieve the encryption key.

  3. Key management verifies your certificate. Once you pass this check, your key management sends its certificate for acceptance and authentication.

  4. If the certificates look good, the network establishes a secure connection between key management and you.

  5. Key management decrypts your requested key and sends it to you through an encrypted session.

  6. The API (Application Programming Interface) dispatches your code to your storage, file system, application, or database. It can now be stored in temporary memory.

  7. The storage, file system, application, or database sends you plaintext information, allowing you to access the system freely.

Another interesting feature of encryption keys is that they have a life cycle. It’s comprised of the following stages:

  • Creation
  • Use
  • Revocation
  • Back up
  • Deletion (destruction)
  • There’s also a broader categorization:
  • Pre-operational
  • Operational
  • Post-operational
  • Deletion

Regardless of the phases you use to describe your data encryption, each life cycle has a crypto period. This is the period during which your specific code is authorized for use. It’s determined by combining two periods:  

  • The period when the key will be decrypted (recipient usage period)
  • The estimated period of how long the encryption will apply to your encrypted data (originator usage period)

For example, say your data is encrypted for the next half a year, and you keep adding a session key from time to time. Then, your originator usage period is six months.

Let’s also assume that your database can be accessed by other authorized users for two years. In this case, the recipient usage period and originator usage period would be the same – two years.

Both examples illustrate crypto periods. It’s six months in the first instance, whereas it extends to two years in the other one. Regardless of the timeframe, the encryption key must be active throughout its duration.

However, your organization might want to tweak the public key infrastructure, so you’ll need to take other factors into account. You may also wish to use encryption and decryption for decades. Either way, you might want to limit certain aspects, such as:

  • Amount of data protected by a single key
  • Degree of exposure in the event your secret key gets compromised
  • Time intruders need to penetrate your logical, procedural, and physical barriers
  • Period when data can be jeopardized by inadvertent access
  • Period available for intense cryptanalytic attacks
  • This can be boiled down in simpler terms:
  • How long will the system use your encryption keys?
  • How will the data encrypted be used?
  • How much information is encrypted?
  • How sensitive or important is your information?
  • What would be the damage if the encryption key is lost, or your information is exposed?

The sensitivity aspect might be the most significant part of your encryption process. Here’s a general rule of thumb: the more sensitive your data encrypted is, the shorter its lifetime should be.

This means you should change your code periodically rather than use the same key year in and year out. Attackers will be less likely to break the encryption and figure out how your key is used.

Accordingly, authorized access to the protected data may extend beyond the lifespan of your encrypted key. If so, you’ll need to archive your deactivated codes and only use them for decryption.

This brings us to the essence of a proper key management system. Once your old key decrypts the data, a new code can be used to protect the information. Over time, your original string is no longer necessary, allowing you to delete it.

Encryption Key Types

Encryption keys fall into two categories:

Symmetric Keys

Symmetric encryption is based on symmetric keys. In this arrangement, just one secret key is used to decrypt and encrypt electronic information. The entities communicating this way must perform a key exchange to initiate the process.

By using a symmetric key algorithm, you can scramble information to make it understandable only to individuals with access to the shared secret key. Once the recipient receives the message, symmetric algorithms reverse the action and return the data in a readable form.

The single key used by the recipient and sender can be a specific code or password. It can also consist of random numbers or letters randomly generated by secure technology. For banking symmetric encryption, the keys are created with a certified generator that adheres to certain industry standards.

There are two groups of symmetric encryption keys:

  • Stream keys – These encryption algorithms protect data in streams rather than hold it in your system’s memory.
  • Block keys – A set length of data is encrypted in electronic data blocks that can be accessed with one key. As the manager encrypts data, the network retains information in the memory and waits for blocks to assemble.
  • Here are the most common instances of symmetric encryption:
  • Advanced Encryption Standard (AES)
  • Data Encryption Standard (DES keys)
  • International Data Encryption Algorithms (IDEAs)
  • Blowfish
  • Rivest Cipher 4, 5, or 6

Asymmetric Keys

Unlike symmetric encryption, asymmetric encryption features two related keys: public and private keys. The former is required for encryption, whereas the other key is needed for decryption. This way, only authenticated recipients can decrypt your message.

Let’s break down asymmetric encryption with a straightforward example. Suppose you’re a business owner and need a mechanism for employees to enter your system securely. They don’t need a two-way communication channel because they already have orders. All they need is to send regular reports.

That’s where asymmetric keys come into play. Team members can use the public key infrastructure to encrypt information. In turn, you can decrypt the data with your corresponding private key. The result is virtually impenetrable one-way communication.

Asymmetric algorithms are essential for asymmetric encryption. They create the key pairs through a secure generation protocol that connects the codes. The relationship between the private and public keys can differ depending on the structure of the algorithms.

What’s the Difference Between an Asymmetric and Symmetric Key?

The biggest difference between asymmetric and symmetric keys is the number of codes. On the one hand, symmetric models have just one code for both encryption and decryption, while asymmetric systems have a key pair.

Resource consumption is another difference between the two systems. Symmetric models generally require low resources. Meanwhile, asymmetric encryption is resource-intensive.

Furthermore, symmetric algorithms have smaller cipher text than the original file, while asymmetric systems feature larger cipher text.

The arrangements have their benefits and drawbacks. For example, symmetric algorithms are faster than their asymmetric counterparts. They can also process a vast number of keys with minimal costs. The downside is that you need to keep it secret while transmitting it to your recipient. Fail to do so, and the message can be intercepted and decrypted by eavesdroppers.

Asymmetric algorithms are slower than symmetric systems and can’t handle large amounts of data. However, they’re more secure because they require two keys for encryption and decryption. Therefore, an intruder can’t infiltrate the system if they have just one code.

Lifespan of a Private Key

We’ve already mentioned the phases of the encryption key life cycle. The next section is an in-depth explanation of each stage.


This is where encryption keys are generated and transferred to your key management server. The creator makes the code using a secure generator and stores it in a bulletproof database alongside its attributes:

  • Name
  • Size
  • Activation date
  • Version
  • Deletion capacity
  • Rollover
  • Access
  • Mirroring

You can activate your encryption key upon creation. Alternatively, you can opt for annual or automatic activation at some other time.

The manager plays a pivotal role in key security. They need to track past and current versions of your code and implement the necessary changes. Additionally, they should let you choose whether you can delete your string, mirror it to another unit, or limit access. Plus, they need to grant you unrestricted access to the attributes, so you can adjust them.


At this stage of the encryption process, your manager typically allows authorized users and systems to retrieve the code for encryption and decryption. It also involves organizing past and current versions of the key.

The bulk of the work comes down to deactivating and activating keys. For instance, assume your new encryption key is created, and the original one is deactivated every year. Then, previous versions should be retained, but they should only be used for decryption. Only the current instance should be distributed for encryption.

Afterward, the manager rolls your encryption key through an established schedule. They can also allow you to manually distribute your code.


If you’re the administrator, you should have access to all functions of your key manager. One of the most important features is revocation. In other words, you should be able to revoke any encryption key that’s no longer necessary for decryption and encryption requests.

You can reactivate revoked encryption keys if you need to decrypt information previously secured with it. However, you can restrict this function too.

Back up

You need to keep an archive for your code. More specifically, you need to store your deactivated encryption keys in a safe place. This protects the data from unauthorized modifications, additions, and deletions.

Your encryption key should also be recoverable at the end of the crypto period and allow for reconstruction. This is because you may need to decrypt data with a deactivated code. Archiving the strings rather than deleting them lets you do so.


If your encryption keys are no longer usable or have been compromised, you can delete them from your storage database. The manager can remove the code and all versions or just particular versions.

If you opt for complete deletion, you’ll no longer be able to recover the key unless you’ve created your backup image. Consider this option if your sensitive information has been infiltrated in an encrypted state. Once it’s removed from the system, the data will be unrecoverable and secure. Recreating the necessary encryption key will be impossible.

Keep Cyber Criminals at Bay with Bulletproof Key Encryption

There’s no telling how much damage malicious actors can cause if they breach your defenses. Your reputation is at stake, and you can lose a lot of money if they access your bank account.

To minimize this risk, optimize your security with encryption keys. Whether you opt for symmetric or asymmetric models, you’ll make your system much more robust.

How to stay safe online:

  • Practice Strong Password Hygiene: Use a unique and complex password for each account. A password manager can help generate and store them. In addition, enable two-factor authentication (2FA) whenever available.
  • Invest in Your Safety: Buying the best antivirus for Windows 11 is key for your online security. A high-quality antivirus like Norton, McAfee, or Bitdefender will safeguard your PC from various online threats, including malware, ransomware, and spyware.
  • Be Wary of Phishing Attempts: Be cautious when receiving suspicious communications that ask for personal information. Legitimate businesses will never ask for sensitive details via email or text. Before clicking on any links, ensure the sender's authenticity.
  • Stay Informed. We cover a wide range of cybersecurity topics on our blog. And there are several credible sources offering threat reports and recommendations, such as NIST, CISA, FBI, ENISA, Symantec, Verizon, Cisco, Crowdstrike, and many more.

Happy surfing!

Frequently Asked Questions

Below are the most frequently asked questions.

What is TLS in encryption?

TLS stands for Transport Layer Security. This cryptographic protocol provides extra security with mutual authentication over a safe computer network. It’s widely used in instant messaging and emails.

What is CA in cryptography?

CA refers to Certificate Authority. These digital certificates cryptographically connect entities with their public keys. Browsers use them to examine server content and ensure credible traffic.

What is a hardware security module?

A hardware security module is a tamper-resistant device that secures encryption processes by generating, managing, and protecting keys. They’re tested to meet strict security standards.
Author: Tibor Moes

Author: Tibor Moes

Founder & Chief Editor at SoftwareLab

Tibor has tested 39 antivirus programs and 30 VPN services, and holds a Cybersecurity Graduate Certificate from Stanford University.

He uses Norton to protect his devices, CyberGhost for his privacy, and Dashlane for his passwords.

You can find him on LinkedIn or contact him here.