Information security is now a priority for organisations in every sector. For this reason, data encryption at rest plays a crucial role in protecting sensitive information. The concept refers to the practice of encrypting data stored on hard drives, databases or other media, rather than data in transit across networks. This measure is fundamental to ensure that, even if someone gains unauthorised physical access to storage devices, the data remains unreadable and secure.
For document management platforms, which often handle significant volumes of confidential data, encryption at rest helps to comply with data protection regulations. In addition, it strengthens the trust of customers and partners. This article examines the concept in detail, its advantages, the challenges it poses and good practice for effective implementation.
What is data encryption at rest
Data encryption at rest is the process of using cryptographic algorithms to turn stored data into a format that unauthorised users cannot read. It applies to data that is neither moving nor being actively processed, but is instead kept on some kind of media, such as hard drives, SSDs, servers, databases or even mobile devices.
The difference between data at rest, in transit and in use
- Data at rest: Stored data that is waiting to be used or has been archived.
- Data in transit: Data travelling across networks, such as emails or file transfers.
- Data in use: Data being actively processed, for example when a user opens it in an application or views it.
This type of encryption protects stored information against threats such as stolen hard drives, unauthorised physical access to servers or cyberattacks that aim to extract data from compromised devices.
Types of data encryption at rest
Disk-level encryption: The system encrypts the entire storage drive. Examples include Microsoft BitLocker and Apple FileVault.
File or folder-level encryption: Encrypts only specific files or directories, allowing more granular data management.
Database-level encryption: Implemented directly in the database, ensuring that data stored in specific tables and columns is encrypted.
Advantages of data encryption at rest
Implementing data encryption at rest offers several significant advantages, especially for organisations that manage large volumes of sensitive information.
Protection against unauthorised access
If someone steals or gains unauthorised access to an encrypted hard drive or any other storage device, the stored data remains inaccessible without the decryption key. This provides an extra layer of security, even when devices are lost or stolen.
Regulatory compliance
Many international data protection regulations, such as the General Data Protection Regulation (GDPR) in the European Union, require organisations to protect personal data against unauthorised access. The GDPR does not make encryption mandatory in every case, but Article 32 expressly lists it as an appropriate measure. In addition, encryption helps to reduce the risk of fines and penalties.
Mitigating risk in security incidents
In the event of a security breach, encryption can make the difference between a minor incident and a major disaster. If the data is encrypted, attackers cannot read or use the information, even if they manage to access the systems.
Greater customer trust
Organisations that encrypt stored data show a serious commitment to protecting their customers’ privacy and security. As a result, this can increase customer trust and strengthen business relationships.
Challenges in implementing data encryption at rest
Although this type of encryption offers many advantages, implementing it is not without challenges.
Key management
The security of encryption depends largely on protecting the cryptographic keys. Key management, including creation, secure storage, rotation and deletion, is one of the most complex challenges in implementing encryption. Poor key management can compromise the entire encryption strategy.
Impact on performance
Encrypting and decrypting data can add latency to read and write operations, especially in large-scale storage systems. Although technology has advanced to minimise this impact, it is important to consider performance needs during implementation.
Compatibility with legacy systems
Implementing data encryption at rest can become complicated in environments with legacy systems. These systems may not support modern cryptographic algorithms, or may support them only partly. This may require systems to be upgraded or replaced, increasing the cost and complexity of implementation.
Recovery after failure
If cryptographic keys are lost or compromised, data recovery may become impossible, resulting in the permanent loss of information. Organisations should therefore implement robust backup and recovery strategies to mitigate this risk.
Best practice for implementation
To ensure data encryption at rest is implemented successfully, organisations should follow some good practices.
Risk and requirements assessment
Before implementing encryption, organisations should carry out a detailed assessment of security risks and requirements, identifying which data needs encrypting and the level of protection required.
Choosing encryption algorithms
The choice of encryption algorithm is critical to data security. Experts recommend, for example, widely accepted algorithms such as AES (Advanced Encryption Standard) with 256-bit keys, for their robustness and performance.
Implementing a key management system (KMS)
A key management system (KMS) is essential for managing cryptographic keys securely and effectively. Using a KMS allows keys to be created, rotated and stored securely, minimising the risk of compromise.
Integration with security policies
Organisations should build data encryption at rest into their security policies, alongside other protective measures such as access control, multi-factor authentication and activity monitoring.
Training and awareness
Employee training is fundamental to ensure that everyone follows encryption practices correctly. All users should be aware of their responsibilities for protecting cryptographic keys and complying with security policies.
Regular testing and audits
Regular testing and security audits are essential to ensure that encryption works correctly and that keys are properly protected. These activities make it possible to identify and fix vulnerabilities before anyone exploits them.
What encryption at rest does not protect
Encryption at rest protects against the theft of disks, backups or physical media. However, it does not protect data while the application is using it. If an attacker logs in with a legitimate user’s credentials, the platform decrypts the documents as normal. The organisation should therefore combine it with multi-factor authentication, least-privilege permissions and access monitoring. In addition, with cloud services, it is worth distinguishing between provider-managed encryption and encryption with customer-managed keys, which gives more control but also more responsibility.
Encryption and data breaches
Encryption has an important practical effect under the GDPR. When the data affected by a breach is encrypted with a key that has not been compromised, notifying the data subjects may not be necessary under Article 34. Encryption therefore reduces not only the risk but also the impact of an incident.
Practical example: A lost backup
Suppose a disk containing backups of the document management platform goes missing while being transported to another site. Because the backups were encrypted with AES-256 and the key was kept in a separate KMS, nobody can read the documents. The company then records the incident, assesses the risk and concludes that there is no need to notify the data subjects.
Encryption at rest checklist
- Disks, databases and backups encrypted.
- Current algorithms, such as AES-256.
- Keys stored separately from the data.
- Key rotation defined.
- Recovery tests with the backup keys.
Frequently asked questions
Does encryption at rest make data anonymous?
No. Encrypted data is still personal data, because anyone who holds the key can read it.
Conclusion
Data encryption at rest is an essential security measure for protecting sensitive information stored on document management platforms. With it, data remains unreadable to anyone who does not hold the decryption key. Consequently, organisations can significantly reduce the risks of unauthorised access, security breaches and theft of storage devices. However, effective implementation requires a strategic approach, including careful management of cryptographic keys, the choice of robust algorithms and integration with other security policies. By following best practice and overcoming the related challenges, organisations can better protect their data and ensure compliance with data protection regulations. In addition, they preserve the trust of their customers and partners in an increasingly demanding digital environment.
Read also: Data encryption in document management platforms. For further cybersecurity guidance, see the Portuguese National Cybersecurity Centre (CNCS).