What is encryption?

Encryption is a cybersecurity technique that converts readable data, known as plaintext, into an unreadable form called ciphertext. Only authorized users or systems with the correct cryptographic key can decrypt the information and convert it back into its original form.

Encryption helps prevent unauthorized users from reading sensitive information, even if they gain access to the data itself. Organizations use encryption to protect passwords, financial information, customer records, intellectual property, communications, and other sensitive data stored on devices or transmitted across networks.

Encryption is a fundamental part of modern cybersecurity because data rarely stays in one place. It moves between users, applications, endpoints, data centers, and cloud environments. Encrypting that information helps keep it confidential as it travels across increasingly complex IT environments.

Key Takeaways

• Encryption protects sensitive data by converting readable information (plaintext) into unreadable ciphertext using cryptographic algorithms and keys, preventing unauthorized users from accessing the original information.
• The two main types of encryption are symmetric and asymmetric encryption. Both help secure sensitive information, including data at rest in databases and cloud storage and data in transit across networks.
• Encryption is essential for cybersecurity and Zero Trust security. It helps protect confidential information, secure communications, reduce data exposure, and support regulatory compliance requirements.
• Encryption alone cannot prevent cyberattacks or lateral movement. Organizations should combine encryption with visibility, least-privilege access, and segmentation to contain breaches and limit attackers' ability to spread across environments.

How does encryption work?

Encryption uses a mathematical algorithm and a cryptographic key to transform readable data into ciphertext.

The basic encryption process works like this:

1. Plaintext: The original readable data, such as a file, password, or message.
2. Encryption algorithm: A mathematical process transforms the plaintext.
3. Encryption key: A cryptographic key determines how the information is transformed.
4. Ciphertext: The encrypted data becomes unreadable to anyone who does not have the appropriate key.
5. Decryption: An authorized user or system uses the correct key to convert the ciphertext back into readable information.

The strength of encryption depends on factors including the encryption algorithm, key length, implementation, and how securely encryption keys are managed.

Why is encryption important in cybersecurity?

Encryption protects sensitive information when other security controls fail.

Attackers may bypass perimeter defenses, compromise credentials, exploit vulnerabilities, or gain access to devices and cloud resources. Encryption adds another layer of protection by making the underlying information unreadable without the appropriate key.

Encryption can help organizations:

• Protect sensitive and confidential information
• Reduce the risk of data exposure during a breach
• Secure communications between users, applications, and workloads
• Protect information stored in cloud and on-premises environments
• Support privacy and regulatory compliance requirements
• Reduce the impact of lost or stolen devices

Encryption is particularly important as organizations adopt cloud services, hybrid infrastructure, remote work, and distributed applications that constantly exchange information across networks.

What are the main types of encryption?

The two primary types of encryption are symmetric encryption and asymmetric encryption. Both protect information using cryptographic keys, but they handle those keys differently.

Symmetric encryption

Symmetric encryption uses the same secret key to encrypt and decrypt data.

Because only one key is required, symmetric encryption is generally fast and efficient. This makes it well suited for encrypting large amounts of data.

Advanced Encryption Standard (AES) is one of the most widely used symmetric encryption algorithms. AES can be used to protect files, databases, storage devices, applications, and other sensitive information.

The primary challenge with symmetric encryption is key management. Anyone who obtains the secret key may be able to decrypt the protected information, making it critical to securely distribute, store, and manage encryption keys.

Asymmetric encryption

Asymmetric encryption, also known as public-key encryption, uses two related cryptographic keys: a public key and a private key.

The public key can be shared, while the private key must remain protected. Information encrypted with the appropriate public key can only be decrypted with the corresponding private key.

Asymmetric encryption is commonly used to establish secure communications, exchange cryptographic keys, and support technologies such as digital certificates and secure web connections.

What is the difference between encryption at rest and encryption in transit?

Encryption can protect information in different states. Two of the most common are data at rest and data in transit.

Encryption at rest

Encryption at rest protects information while it is stored rather than actively moving between systems.

Examples include data stored in:

• 데이터베이스
• Hard drives
• Cloud storage
• 서버
• Backups
• 모바일 장치
• Removable storage

If an attacker steals a device or gains unauthorized access to a storage system, encryption can prevent them from immediately reading the underlying information.

Encryption in transit

Encryption in transit protects information while it moves between devices, applications, networks, or services.

For example, Transport Layer Security (TLS) is commonly used to encrypt communications between web browsers and websites. Encryption can also protect traffic moving between applications and workloads across cloud and hybrid environments.

Protecting data in transit is especially important because information may cross networks that an organization does not fully control.

What is end-to-end encryption?

End-to-end encryption (E2EE) protects data so that it can only be read by the intended sender and recipient.

With properly implemented end-to-end encryption, data remains encrypted as it travels through intermediate networks, servers, and service providers. Those intermediary systems facilitate the communication but do not have the keys needed to read the underlying content.

End-to-end encryption is commonly associated with secure messaging and communications platforms, but the broader concept illustrates an important cybersecurity principle: sensitive information should remain protected throughout its journey, not only at individual points along the way.

What are encryption keys?

An encryption key is a value used by a cryptographic algorithm to encrypt or decrypt information.

Keys are one of the most important components of an encryption system. Strong encryption can still be undermined if an attacker steals, exposes, or gains unauthorized access to its cryptographic keys.

This makes key management a critical part of an organization's security strategy. Organizations need processes for securely generating, storing, distributing, rotating, revoking, and eventually destroying cryptographic keys.

Keys should also be protected with strong access controls so that users and systems only have access to the keys they actually need.

What is the difference between encryption and hashing?

Encryption and hashing both transform data, but they serve different purposes.

Encryption is designed to be reversible. Authorized users with the correct key can decrypt encrypted information and restore the original data.

Hashing is generally designed to be one-way. A hashing algorithm converts data into a fixed-length value called a hash or digest. The original information is not intended to be recovered from that value.

Encryption is commonly used to protect confidential information, while hashing is frequently used for tasks such as verifying data integrity and securely storing password verifiers.

What is the difference between encryption and tokenization?

Encryption protects sensitive data by mathematically transforming it into ciphertext. With the appropriate key, the ciphertext can be decrypted back into its original form.

Tokenization replaces sensitive information with a non-sensitive substitute known as a token. The original information is typically stored separately in a secure system that maps the token back to the original value.

Both approaches can reduce data exposure, but they work differently and may be used for different security and compliance requirements.

Can encrypted data still be breached?

Yes. Encryption significantly reduces the risk of exposing sensitive information, but encryption alone cannot prevent a cyberattack.

Attackers may steal encryption keys, compromise an authorized account, access information after it has been decrypted, exploit an application vulnerability, or move laterally to other systems within the environment.

For this reason, encryption should be part of a layered cybersecurity strategy that also includes identity and access management, monitoring, endpoint security, segmentation, vulnerability management, and other security controls.

How does encryption support Zero Trust security?

Encryption and Zero Trust address different parts of the security problem.

Encryption protects the confidentiality of data. Zero Trust focuses on continuously verifying access and limiting users, devices, applications, and workloads to the resources they need.

Together, these controls provide stronger protection. Encryption can make intercepted or stolen data unreadable, while Zero Trust controls help restrict who and what can access systems containing that data in the first place.

Microsegmentation adds another layer by restricting communication between workloads and applications. If an attacker compromises one system, segmentation can prevent that system from freely communicating with other resources and help stop lateral movement.

This matters because encryption does not automatically stop an attacker who has already obtained legitimate credentials or access to a system where data is decrypted.

Encryption and breach containment

Encryption is an important data-protection control, but organizations also need to prepare for what happens when an attacker gets inside the environment.

A compromised workload may have legitimate access to encrypted data or possess the credentials needed to communicate with other systems. In those situations, encryption alone may not prevent an attacker from moving deeper into the network.

Breach containment limits how far an attack can spread. By combining encryption with visibility, least-privilege access, and segmentation, organizations can protect sensitive data while restricting the pathways attackers can use to reach additional applications and workloads.

How Illumio complements encryption

Encryption helps protect the confidentiality of data. Illumio helps protect the systems and workloads that store, process, and exchange that data.

Illumio provides visibility into communication and dependencies across hybrid and multi-cloud environments. This allows security teams to understand how workloads communicate and identify unnecessary or risky connections.

Illumio Segmentation can then enforce least-privilege communication between workloads, applications, and environments. If an attacker compromises a system, segmentation helps prevent unauthorized lateral movement and contains the breach before it reaches additional critical resources.

Together, encryption and segmentation provide complementary layers of protection: encryption makes sensitive information difficult to read without authorization, while segmentation limits an attacker's ability to reach the systems containing that information.

See the Risks Encryption Can’t Stop

Encryption protects sensitive data, but it can’t tell you when a compromised workload is communicating with unexpected systems or an attacker is beginning to move laterally.

Illumio Insights gives security teams visibility into how workloads communicate, detect potential threats, and identify lateral movement before an attack spreads.

See the threats hiding in your network and get the intelligence you need to contain them faster.

Illumio Insights 살펴보기 →

자주 묻는 질문

What is encryption in simple terms?

Encryption is the process of turning readable information into an unreadable format so unauthorized people cannot understand it. An authorized user or system can use the correct cryptographic key to decrypt the information and make it readable again.

What is an example of encryption?

A common example is HTTPS. When you visit a website using HTTPS, TLS helps encrypt information exchanged between your browser and the website, protecting the data while it travels across the network.

What are the two main types of encryption?

The two main types are symmetric and asymmetric encryption. Symmetric encryption uses the same secret key for encryption and decryption. Asymmetric encryption uses a pair of related keys, typically a public key and a private key.

What is AES encryption?

Advanced Encryption Standard (AES) is a symmetric encryption algorithm widely used to protect digital information. AES supports different key sizes, including 128, 192, and 256 bits.

What is the difference between encryption and decryption?

Encryption converts readable plaintext into unreadable ciphertext. Decryption reverses that process, converting ciphertext back into readable data using the appropriate cryptographic key.

Does encryption prevent cyberattacks?

No. Encryption protects data from unauthorized disclosure, but it does not stop every type of cyberattack. Attackers may compromise credentials, steal encryption keys, exploit vulnerabilities, or access data after an authorized system decrypts it. Encryption works best as one layer of a broader cybersecurity strategy.

Why is encryption important for Zero Trust?

Encryption protects data as it is stored and transmitted, while Zero Trust controls who and what can access resources. Used together with least-privilege access and segmentation, encryption helps organizations build layered protection around sensitive data and critical systems.

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