Every time you check your bank balance, send a text message, or buy something online, encryption is working quietly in the background to keep your information private. Most people never see it, but without it, passwords, credit card numbers, medical records, and private conversations would travel across the internet in plain sight.
So what is encryption, exactly? This guide explains it in simple terms: how encryption works, the main types, where you use it every day, and why it is one of the most important tools in cybersecurity.
Encryption scrambles readable information into an unreadable format so only authorized people can understand it. The readable version is called plaintext. The scrambled version is called ciphertext.
To turn ciphertext back into plaintext, you need the right key. Without that key, encrypted data looks like random characters and is useless to anyone who intercepts or steals it.
A simple way to think about it: encryption is like putting a letter in a locked box before mailing it. Anyone can see the box, but only the person with the key can open it and read what is inside.
Encryption protects data in three important ways:
These goals sit at the heart of both information security and cybersecurity. If you are curious how the two fields differ, see information security vs. cybersecurity.
Encryption also matters for compliance. Many regulations and frameworks expect organizations to encrypt sensitive data, including health information, financial records, and government data. Learn more in our overview of cybersecurity compliance frameworks.
At its core, encryption uses two ingredients:
Here is a simplified example. An old technique called the Caesar cipher shifts each letter by a set number of places. With a shift of 3, the word “HELLO” becomes “KHOOR.” The algorithm is “shift the letters,” and the key is “3.”
Modern encryption follows the same basic idea but uses complex mathematics and extremely long keys. A modern encryption key can have so many possible combinations that brute-forcing it would take today’s computers an impractically long time.
The security of good encryption depends on keeping the key secret, not the algorithm. Strong algorithms are public and have been heavily tested by experts worldwide.
There are two main types of encryption: symmetric and asymmetric. Most real-world systems use both together.
Symmetric encryption uses a single shared key to encrypt and decrypt data. It is fast and efficient, making it ideal for encrypting large amounts of data, such as files, hard drives, and databases.
The challenge is key sharing. Both parties need the same key, and they must exchange it safely. If an attacker intercepts it, they can read everything.
Common symmetric algorithms:
Asymmetric encryption, also called public key encryption, uses two mathematically linked keys:
Think of the public key as an open mailbox slot. Anyone can drop a letter in, but only the owner with the private key can open the box and read the mail.
Asymmetric encryption solves the key-sharing problem, but it is slower than symmetric encryption. It is commonly used to securely exchange keys and create digital signatures.
Common asymmetric algorithms:
When you visit a secure website, your browser and the server use asymmetric encryption to safely agree on a shared secret key. Then they switch to faster symmetric encryption for the rest of the session. This hybrid approach gives you the security of public key cryptography and the speed of symmetric encryption.
Hashing is often mentioned alongside encryption, but it is different. Encryption is reversible with the right key. Hashing is a one-way process that turns data into a fixed-length string, called a hash, that cannot be reversed to recover the original.
Hashing is used to store passwords securely and verify that files haven’t been altered. If even one character of the original data changes, the hash changes completely. Common hashing algorithms include SHA-256 and SHA-3, while password storage typically uses specialized algorithms like bcrypt or Argon2.
Security professionals often describe encryption based on the data’s state.
This protects stored data, such as files on a laptop, database records, or cloud backups. If a device is lost or a server is breached, encrypted data at rest remains unreadable without the key. Database security is a common focus area; see how teams approach securing open-source databases.
This protects data while it moves between devices, such as when you load a website, send an email, or connect to a company network. Protocols like TLS (Transport Layer Security) encrypt this traffic so attackers cannot read it as it travels. Encryption in transit works alongside other network security controls like firewalls and secure remote access.
End-to-end encryption (E2EE) encrypts data on the sender’s device and decrypts it only on the recipient’s device. Even the service provider in the middle cannot read it. Many messaging apps use E2EE to protect private conversations.
You probably use encryption dozens of times a day without noticing:
Encryption is powerful, but it is not a complete security solution on its own.
Encryption can:
Encryption cannot:
That is why encryption works best as one layer of a broader strategy, including access controls, monitoring, and a zero trust security model.
Even the strongest encryption fails if the keys aren’t protected. Key management covers how keys are created, stored, rotated, shared, and destroyed.
Best practices include storing keys separately from the data they protect, using hardware security modules (HSMs) or cloud key management services, rotating keys regularly, and limiting access. Many data breaches happen not because encryption was broken, but because keys or credentials were exposed.
Today’s public key systems, such as RSA and ECC, rely on math problems that are extremely hard for classical computers to solve. Powerful future quantum computers could solve some of those problems much faster, putting current public-key encryption at risk.
To prepare, NIST published its first post-quantum cryptography standards in August 2024. These new algorithms are designed to resist attacks from both classical and quantum computers. Organizations are beginning to inventory where they use encryption today so they can migrate to quantum-resistant algorithms over time.
Encryption knowledge is valuable across many cybersecurity and IT roles, including:
Explore more roles in our guide to cybersecurity jobs.
Many industry certifications test your understanding of cryptography and data protection:
CIAT’s Unlimited Certification Exam Retake Policy covers all CompTIA certifications, including Security+. The policy excludes CISSP and EC-Council CEH.
Encryption protects nearly everything we do online, from banking and shopping to messaging and cloud storage. Symmetric encryption quickly secures large amounts of data. Asymmetric encryption makes it safe to share keys and verify identities. Together, they keep sensitive information unreadable to anyone who shouldn’t see it. But encryption is only as strong as the people and processes around it, which is why organizations need professionals who can implement it correctly and manage keys securely.
Understanding encryption is one of the first steps toward a career in cybersecurity. CIAT’s cybersecurity programs cover cryptography and secure communication protocols, along with network security, cloud security, and incident response. The 5-day CompTIA Security+ Bootcamp prepares you for the Security+ certification, one of the most requested credentials in entry-level security roles.
Ready to learn how to protect the data the world runs on?
Encryption scrambles information so only someone with the right key can read it. To anyone else, encrypted data looks like random, meaningless characters.
Symmetric encryption uses a single shared key to encrypt and decrypt data, making it fast. Asymmetric encryption uses a public key to encrypt and a separate private key to decrypt, which makes key sharing safer but slower. Most systems use both together.
AES (Advanced Encryption Standard) is the most widely used symmetric encryption algorithm. It protects everything from Wi-Fi traffic and hard drives to government and financial data.
Modern encryption like AES-256 is considered practically unbreakable by brute force. Most successful attacks target weaknesses around encryption instead, such as stolen passwords, exposed keys, outdated algorithms, or misconfigured systems.
End-to-end encryption means data is encrypted on the sender’s device and only decrypted on the recipient’s device. Not even the company running the service can read it in between.
Encryption is reversible with the correct key. Hashing is one-way: it turns data into a fixed-length value that cannot be converted back. Hashing is commonly used to store passwords and verify file integrity.
HTTPS means your connection to the website is encrypted, so data can’t be easily read in transit. It does not guarantee the website itself is trustworthy. Phishing sites can also use HTTPS.
Encryption at rest protects stored data, such as files on a laptop, records in a database, or backups in the cloud, so it stays unreadable if a device or server is compromised.
Future large-scale quantum computers could break some of today’s public key encryption methods, such as RSA and ECC. That is why NIST released post-quantum cryptography standards in 2024 and organizations are starting to plan their migration.
CompTIA Security+ is a strong starting point because it covers cryptography basics, PKI, and secure protocols. CISSP covers cryptography at a more advanced level for experienced professionals.
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