What Is an Encryption Algorithm? A Practical Guide for Security Teams
Understand what an encryption algorithm is, how it works, and how security teams use cryptographic algorithms to protect sensitive data.
Introduction
“Encryption” shows up everywhere in cybersecurity, but terms like encryption algorithm, crypto algorithm, and cipher algorithm can still feel abstract. In reality, every secure connection, VPN tunnel, and protected database you use is powered by one or more cryptographic algorithms behind the scenes.
At a basic level, encryption is about turning readable data into unreadable data so that only authorized people or systems can get it back. This guide explains what an encryption algorithm is, how encryption works at a high level, the main types of encryption algorithms, and which common encryption methods you will see most often in practice.
What Is an Encryption Algorithm?
An encryption algorithm is a defined set of mathematical steps that converts plaintext (readable data) into ciphertext (unreadable data) using an encryption key. It is the core “recipe” that decides how data is scrambled. When people say cryptographic algorithm, cryptography algorithm, or security algorithm in this context, they usually mean this same idea.
The definition of encryption in computer systems is simple: it protects confidentiality. If an attacker steals encrypted data but does not have the key, the encryption algorithm should make it computationally infeasible to recover the original information. The strength of an encryption method comes from both the design of the algorithm and the size and protection of the keys used with it.
How Does Encryption Work?
Conceptually, most encryption techniques follow the same basic flow:
Plaintext ↓ Encryption algorithm + encryption key ↓ Ciphertext (unreadable) ↓ Decryption algorithm + key ↓ Plaintext (restored)
The encryption key algorithm defines how the key interacts with the data. With the correct key, the decryption process reverses the transformation and returns the original plaintext. Without the key, the ciphertext should look like random data. When people ask “encryption, how does it work?” or “what does encryption mean in cybersecurity?”, this reversible, key-based transformation is the core answer.
Types of Encryption Algorithms
There are several important types of encryption algorithms you will see in common encryption algorithms lists and protocol documentation.
Symmetric vs Asymmetric
- Symmetric encryption algorithms use the same key to encrypt and decrypt data. They are fast and used for bulk encryption (for example, full-disk encryption or database field encryption).
- Asymmetric encryption algorithms use a public/private key pair. They are used for things like key exchange and digital signatures, rather than large data encryption.
Block vs Stream
- Block ciphers encrypt data in fixed-size blocks (for example, 128 bits at a time). AES is the most widely used modern block cipher.
- Stream ciphers encrypt data as a continuous stream of bits or bytes and are often used when data arrives in real time.
In real systems, the encryption algorithm is combined with an encryption protocol (such as TLS) and modes of operation. Together, these define the full encryption methodology used by an application or service.
Common Encryption Algorithms
Most modern systems rely on a relatively small group of well-reviewed, strong encryption algorithms. Examples include:
- AES (Advanced Encryption Standard) – the de facto standard symmetric cipher for data at rest and in transit
- ChaCha20 – a modern stream cipher used in some TLS and VPN configurations
- RSA – an asymmetric algorithm used for key exchange and digital signatures
- Elliptic-curve algorithms – such as ECDH and ECDSA, used for efficient key agreement and signing
Older or proprietary encription algorithms and weak cipher choices (like legacy DES or outdated modes) should be avoided in new designs. For most use cases, following current recommendations from major vendors and standards bodies is the safest way to choose a good encryption algorithm.
FAQs
What is the simple definition of encryption?
Encryption is the process of converting readable data into unreadable data using a cryptographic algorithm and a key, so only authorized parties can turn it back into its original form.
What is the difference between an encryption algorithm and a cryptographic algorithm?
“Cryptographic algorithm” is a broader term that includes encryption, hashing, and signing. An encryption algorithm is a specific cryptographic algorithm focused on confidentiality.
What does encryption mean in cybersecurity?
In cybersecurity, encryption means protecting data in storage or in transit so that even if it is intercepted or stolen, it cannot be read without the correct decryption key.
Are all encryption algorithms equally secure?
No. Some algorithms are considered strong encryption algorithms by today’s standards, while others are outdated or broken. Using modern, widely reviewed algorithms with appropriate key sizes is critical for real security.
