Encryption at rest: The encryption of data while it is stored, for example in databases, file storage or backups, so that the stored copy is unreadable without the corresponding decryption keys.
Also known as: Data-at-rest encryption, Storage encryption
Key takeaways
- Encryption at rest protects stored data; encryption in transit protects data while it moves.
- It defends against stolen disks, leaked backups and unauthorized access to raw storage.
- It does not stop someone with legitimate application access from reading data through the app.
- Its real strength depends on key management: where keys live and who can use them.
- C Chat encrypts stored messages with AES-256 using a per-organization key.
Data spends most of its life sitting still. A message is in transit for a fraction of a second and then stored for months or years. That is why encryption at rest matters as much as protecting the connection, and why “is it encrypted?” always needs the follow-up “where, and with whose keys?”
Encryption at rest: a plain definition
“At rest” refers to data in storage, as opposed to data moving across a network (“in transit”) or data being processed in memory (“in use”). Encryption at rest scrambles stored data so the bytes on the disk are meaningless without the key.
Where it is applied varies:
| Layer | What is encrypted | Typical protection |
|---|---|---|
| Disk or volume | The whole drive | Stolen or discarded hardware |
| Database or storage service | Tables, files, objects | Copied databases, leaked backups |
| Application level | Specific records or fields, often per customer | Separation between customers, finer control |
Many services combine layers. The application level is where per-customer separation usually happens, a topic covered in per-organization encryption keys.
How it works
The service generates encryption keys and uses a symmetric cipher, most often AES-256, to encrypt data before writing it to storage. When an authorized part of the system needs the data, it uses the key to decrypt it.
The keys themselves are the critical asset. If they sit next to the encrypted data in plain form, encryption adds little. Good practice keeps keys separate, restricts which systems can use them, and records their use. That discipline is called key management.
Encryption at rest is distinct from public-key cryptography, which is mainly used to exchange secrets and verify identities rather than to encrypt large stored datasets.
Why it matters for business messaging
Chat history is a dense archive: names, addresses, photos of sites, client complaints, incident details. Plausible threats against stored data include a misconfigured storage bucket, a backup copied to the wrong place, or a disk that leaves a data center. Encryption at rest turns those events from “data exposed” into “encrypted data exposed”, which is a very different outcome.
It is also one of the first things buyers ask about. The vendor security questionnaire includes it, alongside questions about who can decrypt.
How it relates to C Chat
C Chat encrypts stored messages with AES-256 using a key that belongs to each organization, and protects every connection with TLS. You can read the specifics in AES-256 encryption at rest, per organization and how C Chat encrypts your messages.
What encryption at rest does not decide is who may read content through the product. In C Chat that is defined by the auditable encryption model:
- Team owners and admins can audit and export the team’s group conversations.
- Direct messages between people are private.
- The platform accesses content only for moderation of reported messages or legal requirements, and that access is logged.
This is different from end-to-end encryption, where only devices hold keys. The trade-offs are in auditable encryption vs end-to-end encryption, and the connection side is described in TLS in C Chat.
Related terms and common misconceptions
- “Encrypted at rest means nobody can read it.” Authorized systems decrypt data to serve it. The question is who is authorized.
- “Disk encryption is enough.” It protects hardware, but a running server reads its disk transparently, so it does little against application-level breaches.
- “Encryption at rest and E2EE are interchangeable.” They solve different problems. See per-organization keys explained for how C Chat separates organizations.
Getting started
Moving your team’s chat out of personal apps and into a service with encryption at rest is a quick win. Create a team in the web app at getcchat.com/c; it is free for now with up to 50 members per team.
Frequently asked questions
What is the difference between encryption at rest and in transit?
Encryption in transit protects data while it travels across a network, for example with TLS. Encryption at rest protects it while it sits in storage. A complete approach covers both, because data spends time in each state.
Does encryption at rest protect against hackers?
It protects against attackers who obtain raw storage, such as a copied database file or a backup, without the keys. It does not protect against someone who logs in with valid credentials and reads data through the application.
Is full-disk encryption the same as encryption at rest?
Full-disk encryption is one form of encryption at rest, protecting an entire drive. Services often add encryption at the database or application level as well, which can separate data by customer.
How does C Chat encrypt data at rest?
C Chat stores messages encrypted with AES-256 using a key specific to each organization. Messages also travel over TLS. Team owners and admins can audit group conversations, while direct messages between people remain private.