At its simplest, data encryption is the process of converting readable information into a form that cannot be understood without special permission.
In this way, when we encrypt data, we ensure that even if the data is stolen, intercepted, or accessed outside authorized systems, the attacker still cannot read or use the data.
In today’s landscape, where billions of records are compromised annually due to malware attacks, hacking, or human error, encryption is a fundamental pillar of data security.
For now, let’s make sure the foundational concepts are absolutely clear.
What Is Data Encryption: Key Concepts
When data is created (whether it is a document, a database record, a system log, or any other file), it exists in a readable form called plaintext.
Encryption transforms that plaintext into an unreadable form called ciphertext using a mathematical algorithm and a secret value called a key.
The encryption key is a sequence of bits (generated mathematically) that controls how data is encrypted and decrypted. Without the correct key, the ciphertext cannot be converted back into readable data, even if the encryption algorithm itself is public and well-known.
Security does not come from hiding the algorithm—it comes from protecting the key.
This is a fundamental principle of modern cryptography. Hence, key length becomes an important concept in encryption. It is measured in bits, such as 128 bit, 192 bit, 256 bit, and so on.
Here’s why its length matters.
A 128 bit key has 2¹²⁸ possible combinations—a number with 39 digits.
A 256 bit key has 2²⁵⁶ possible combinations—a number with 78 digits.
To put that into perspective, even with the massive distributed computing power of the most powerful supercomputers today, brute forcing a properly implemented 256 bit key would take billions of years!
This is why modern data encryption standards such as AES 256 are widely trusted and mandated in regulated environments.
How Data Encryption Works at a Technical Level
Encryption is often misunderstood because people mix how it works in theory with how it is applied in real systems.
When we talk about encryption at a theoretical level, what we’re really describing is a system built to address three fundamental security challenges that arise whenever you store, transmit, or process digital data.
1. Confidentiality
The primary goal of encryption is confidentiality, which means ensuring that only authorized parties can read your data. There are two approaches to achieve this—symmetric and asymmetric encryption.
- Symmetric Encryption: The core work of protecting data is almost always done using symmetric encryption. This is where a single secret key encrypts and decrypts data. Symmetric encryption is fast and efficient, which is why it is used to protect large volumes of data—files on disks, database records, backups, and network traffic. Modern data encryption standards such as AES operate in this space.
- Asymmetric Encryption: Symmetric encryption alone has a weakness: the key must somehow be shared securely. This is where asymmetric encryption enters—not to encrypt all data, but to solve the problem of trust. Asymmetric encryption uses a public key and a private key to securely exchange symmetric keys and to prove identity. In practice, asymmetric encryption protects the keys, not the data itself.
2. Integrity
The data must not be changed, corrupted, or tampered with in transit or at rest, whether by accident or by an attacker. You need to know the data you’re seeing is exactly what was originally sent or stored.
To achieve integrity, the techniques used are hashing and message authentication codes (MACs).
- Hashing and Message Authentication Codes (MACs): Once data is encrypted and exchanged, systems must also ensure that it has not been altered. This is the role of hashing and message authentication codes (MACs). Hashes create a fixed fingerprint of data, while MACs combine hashing with a secret key to verify both integrity and authenticity.
3. Trust (Authentication and Non-Repudiation)
You must be able to prove the identity of the party you’re communicating with and in some cases, prove who sent or approved the data (and prevent them from later denying it). This is essential for accountability.
To establish trust (authentication, non-repudiation), there is the concept of digital signatures.
Digital Signatures
Digital signatures extend this trust model further by proving who created or approved the data, and key exchange mechanisms ensure that encryption keys can be established securely over untrusted networks.
Together, these three mechanisms form a single logical flow: keys are exchanged securely, data is encrypted efficiently, integrity is verified continuously, and trust is maintained end to end.
How Data Encryption Works at an Operational Level
When we talk of the different levels of encryption, we mean levels at which encryption applies in real data systems.
1. Data-At-Rest Encryption
Techniques of data encryption at rest are meant to protect data stored on physical media such as hard drives, SSDs, tapes, cloud buckets, or database files. There are two main approaches.
- Full-Disk or Device Encryption: This is “all-or-nothing.” The operating system (e.g., BitLocker on Windows, FileVault on Macs, LUKS on Linux) encrypts the entire drive with a strong key, typically 128 or 256 bits. The user unlocks the device on boot or login.
- Database or Application-Level Encryption: Here, sensitive fields or entire tables are encrypted (this is sometimes also called transparent data encryption (TDE)). This method is widely used in SQL Server, Oracle, and other enterprise databases. With TDE, the application can read/write as usual, but the database files themselves are encrypted “on the fly.” Even if someone copies the files, without the keys, they remain gibberish.
2. Data-In-Transit Encryption
Think of encryption in transit as the shield for your data while it’s moving between two points over any network you do not fully control. This includes the public internet, private WANs, and even Wi-Fi.
The backbone of data-in-transit encryption is formed by protocols like TLS (Transport Layer Security) and its predecessor SSL, which power HTTPS (represented by the “tune” icon in your browser or the “padlock” icon prior to 2026).
Data-in-transit encryption is relevant for more than just websites.
- VPNs use strong encryption (AES, ChaCha20) to build secure “tunnels” between endpoints.
- SSH secures admin logins and file transfers.
- Even routine email, chat, and backups use encryption for data in transit.
Note: Encryption in transit protects data only while it’s moving. Once it lands (at rest), its safety depends on local controls. Endpoints (the sender/receiver) see the data in plaintext; if a device itself is compromised, encryption in transit doesn’t help.
3. Data-In-Use Encryption
Data-in-use encryption refers to protecting data while it is being processed (for instance, in RAM, CPU registers, or specialized secure enclaves).
Traditionally, when you open an encrypted file or a database row, it gets decrypted in memory so the system can “use” it. For a brief window, that data is again plaintext, exposed to anyone who can access memory.
This means that attackers can exploit memory dumps, cold boot attacks, or vulnerabilities to extract secrets.
That is why data-in-use encryption is relevant in situations involving high-stakes data (e.g., banking, healthcare, and regulated sectors).
Most ransomware and malware today still target data at rest or in transit, but sophisticated threats increasingly focus on “data-in-use” vulnerabilities.
This is also why ransomware data recovery services play a critical role in incident response, helping organizations evaluate encrypted systems and recover accessible data wherever possible.
Personal Data Encryption (PDE): What’s New and Why It Matters
Sometimes, encrypting the whole device or network isn’t enough. You need protection for specific files, records, or data fields, either because they’re especially sensitive or because they move outside your control.
This is file-level encryption.
This facility is delivered at scale via the OS feature called Personal Data Encryption (PDE), a part of Windows enterprise environments. Unlike traditional device encryption (BitLocker) or the legacy Encrypted File System (EFS), PDE ties file access directly to your user credentials via Windows Hello for Business.
How Does PDE Work?
- Files and folders are encrypted using keys bound to your identity.
- The decryption key is released only if you authenticate with your Windows Hello credentials. If you log in with just a password or try to open PDE-protected content from another user profile, access is denied, even if you have permission to view the folder itself.
- Remote access (e.g., via RDP) does not automatically unlock PDE-protected data. This is by design.
Security Note: PDE is only as strong as your credential policy. Weak PINs or insecure Hello setups can undermine its benefits. Microsoft recommends disabling hibernation and kernel crash dumps to reduce key exposure, and enterprises should manage PDE deployment via Intune or Group Policy.
Encryption and Data Recovery: What Encryption Does and Does Not Do
At Stellar Data Recovery, we routinely help customers who are unsure whether their encrypted data is lost, recoverable, or gone forever. Here’s what you need to know.
Encryption protects data from unauthorized access. It does not erase any data.
If a disk is encrypted (with BitLocker, TDE, PDE, etc.), the data is still present, just unreadable without the right key or credentials.
Even if the file system is damaged or the OS is corrupt, our Encrypted Data Recovery specialists can recover the files, and you can decrypt them with the key.
Without the key, the data is still “there,” but it is mathematically locked. No forensic technique or data recovery lab can break strong encryption. This means that loss of keys or credentials is functionally equivalent to data loss.
Also, if you’re disposing of or reusing encrypted devices, make sure you destroy or wipe the keys. Use certified erasure tools (like BitRaser) to render encrypted data permanently unrecoverable—even from residual device memory.
In Summary
Encryption is a wall. It is impenetrable when keys are protected but worthless when keys are managed poorly. For IT professionals, the art is in deploying, monitoring, and (critically) backing up the keys.
When in doubt, always ask: Do I have the key, or a valid credential, for this encrypted data? That answer decides whether recovery is possible or not.
If you are dealing with encrypted files, ransomware attacks, or locked storage devices, the following articles can help you understand and resolve these issues.
About The Author
Somdatta is a professional content writer and analyst focused on the storage technology sector, with expertise in both magnetic and flash storage, as well as cloud computing and virtualization concepts. Somdatta translates technical concepts into clear, engaging content to sensitize readers toward a multitude of data loss scenarios and help them gain insights into the nuances of data recovery.
