Note: Product information is correct as of October 25, 2024, and subject to change

Since ancient times, civilizations have sought ways to protect their messages and sensitive information. Early methods, such as the Caesar cipher used by Julius Caesar, involved shifting letters to create secret codes, laying the foundation for basic encryption. As communication methods evolved, so did encryption techniques. The rise of digital platforms brought new complexities as governments and organizations faced the need to protect vast amounts of data transmitted over electronic networks. Encryption with on-premise systems involved end-to-end and network-level encryption techniques, managed internally using hardware security modules (HSMs) for secure key storage and management. Businesses had full physical control over encryption processes, ensuring that sensitive data was protected within a highly controlled environment.

However, as data moved to the cloud with cloud computing, data encryption adapted to meet the unique challenges of securely storing and transferring information in remote data centers. Instead of managing everything within their own walls, businesses now had to protect data that lived in remote data centers, traveled across public networks, and was processed on shared infrastructure. Encrypting data at rest, in transit, and during processing became essential for maintaining confidentiality and integrity across digital boundaries. This blog post will give you a great understanding of cloud encryption, its challenges, and the best practices you can incorporate into your business to help secure your cloud data.

What is cloud encryption?

Cloud encryption is a security method that converts data (text/file/code/image) into unreadable ciphertext using cryptographic algorithms. This helps ensure that even if the data is intercepted or breached, it remains secure and confidential. Cloud encryption protects data against unauthorized access in three states:

• Data at rest: Data stored in the cloud and not moving between devices or networks.

• Data in use: Data being processed, accessed, or used by applications.

• Data in transit: Data moving across networks, between devices, or between servers.

Types of cloud encryption

Understanding the two primary types of cloud encryption—symmetric and asymmetric (also known as public key encryption)—allows you to make informed choices in securing data and improves your business’s cloud security posture management (CSPM).

Symmetric encryption uses a single key to encrypt and decrypt data, requiring both parties to access this shared key, which is exchanged securely beforehand. Asymmetric encryption involves a pair of keys: a public key, which anyone can use to encrypt data, and a private key held by the recipient to decrypt it, helping to ensure that only the intended receiver can access the original data.

How does cloud encryption work?

This image provides a simplified representation of symmetric encryption for general understanding. The configurations may vary depending on the cloud service provider and the particular use case. Real-world implementations often combine multiple encryption methods and additional security measures.

Data encryption

Plaintext data is transformed into ciphertext as a block of binary or hexadecimal values using encryption algorithms like AES or RSA. This helps ensure that the data remains unreadable without the corresponding encryption key. The encryption process occurs on a local device before the data is transmitted to the cloud, adding an extra layer of security. The encryption parameters can be configured based on data sensitivity and regulatory requirements.

Key generation

Encryption relies on keys, which can be generated by the cloud service provider’s key management service (KMS) or self-managed encryption, where users handle their encryption keys. Symmetric keys are used for simpler encryption, like encrypting data at rest (e.g., securing files on a disk or database). Meanwhile, asymmetric keys are preferred for more complex scenarios where data needs to be securely transmitted over an untrusted network (e.g., SSL/TLS encryption for secure communications).

Data transmission

Once encrypted, the data is transmitted to the cloud using secure communication protocols such as transport layer security (TLS). These protocols help protect data in transit from interception and other network threats such as man-in-the-middle (MITM) attacks, packet sniffing, or replay attacks. Only ciphertext is exposed during transmission, reducing the risk of compromised sensitive data.

Data storage

After encrypted data is transmitted, the cloud provider stores it in distributed file systems, object storage (e.g., DigitalOcean Spaces or Amazon S3), or block storage (e.g., DigitalOcean Volumes) in its ciphertext form. The encrypted data, once received, is stored in allocated storage blocks or objects. Each segment is identified for easy retrieval, and the encryption metadata is preserved.

At no point is the plaintext data written to disk. The data remains encrypted until an authorized user or service requests it, helping to ensure confidentiality. Even if unauthorized access to the storage occurs, the data remains unreadable without the corresponding decryption key. During failures, the encrypted data is replicated across data centers for redundancy and durability.

Data decryption

The data is decrypted using the corresponding key through an algorithm (like AES or RSA), reversing the encryption process to restore the original plaintext. Only authorized users or applications with the correct key can decrypt the data. This process is automated by integrating the cloud provider’s services or API calls into workflows.

Benefits of cloud encryption

Cloud encryption gives you the flexibility and control you need to help manage your data securely, making it easy to collaborate and access information remotely without sacrificing security and privacy.

Access control

By managing encryption keys, you can tightly control who accesses your data. Only authorized individuals or systems with the right key can decrypt and access the data, helping to ensure confidentiality. For instance, employee records could be encrypted with keys that only HR directors and payroll systems can access.

Regulatory compliance

Encrypting data can support regulatory requirements by securing sensitive information against unauthorized access, a core expectation in standards like GDPR and HIPAA. Customers are generally more likely to trust companies that demonstrate a commitment to safeguarding their personal information, leading to increased customer loyalty.

Risk mitigation

Encryption reduces the impact of data breaches by helping to ensure that even if data is compromised, it remains unusable to attackers. By safeguarding sensitive information, businesses can uphold their reputation, maintain customer trust, and reduce financial and legal risks.

Challenges of cloud encryption

Implementing cloud encryption requires careful planning and management. From securely handling encryption keys in multi-cloud setups to navigating performance trade-offs and provider limitations, the following factors might complicate data protection in cloud environments.

Key management

Securely managing encryption keys is a complex process.

• If keys are lost, the encrypted data cannot be accessed. If the keys are lost and there’s no backup mechanism to retrieve the encrypted data, the data will be irretrievable.

• If the keys are compromised, attackers can decrypt and access sensitive data, bypassing the encryption entirely.

Performance impact

Encryption might slow down data processing and transfer speeds for large volumes of data. While cloud providers optimize encryption processes, performance trade-offs might still exist. For example, while developing a live media streaming platform, if you transfer large media files to the cloud, the encryption process may add several seconds to the upload time, impacting overall efficiency.

Limited control

You may rely on the provider’s encryption methods when using cloud services, limiting control over security policies. This dependency might be risky if the provider’s encryption standards don’t meet your specific needs.

For example, if your cloud provider uses outdated encryption algorithms that don’t comply with industry regulations, your sensitive data could be at risk in fields like finance, healthcare, or legal services where stringent security standards are essential.

Cloud encryption best practices

When encrypting cloud data, follow foundational practices like Identity and Access Management (IAM), Role-Based Access Control (RBAC), and stringent access controls. Adopt the following cloud encryption best practices to help protect sensitive data from unauthorized access and breaches.

1. Classify data and encrypt

You can identify which data requires encryption based on sensitivity and business needs. Not all data in the cloud may need the same level of protection. Select a cloud provider that offers the appropriate encryption level for your data.

• Low-sensitivity data (e.g., public content) may only require basic encryption for transmission (HTTPS).

• Moderate sensitivity data (e.g., business documents) requires encryption at rest, transit, and during usage.

• High-sensitivity data (e.g., financial or personal) demands end-to-end encryption to help ensure maximum protection.

2. Use strong encryption standards

Prioritize using industry-recognized algorithms like AES-256 to encrypt data at rest and transport layer security (TLS) to secure data in transit. Start by integrating encryption libraries that support these algorithms into your applications.

For instance, when you store sensitive data in databases, use libraries that facilitate AES-256 encryption and ensure the data is automatically encrypted before being written to storage. For web applications, configure TLS certificates correctly to establish secure connections, encrypting all data exchanged between clients and servers. Regularly monitor and update your encryption practices to comply with current security standards and regulations.

3. Practice effective key management

Implement a strong KMS that securely generates and stores keys. Use HSMs to help protect your keys and comply with industry standards.

Establish key rotation policies to automatically change keys at regular intervals, reducing the risk of compromise. Define a clear retirement process that securely destroys old keys to prevent unauthorized access. Regularly audit key usage and access logs to identify any suspicious activity.

4. Devise a backup strategy

Store decryption keys separately from backup data to avoid a single point of failure. For example, you can store your encryption keys in a secure password manager and your backup files in an encrypted cloud storage solution.

When selecting a backup solution, look for features such as end-to-end encryption, strong access controls, and compliance with industry standards. Consider a multi-location backup strategy, which stores keys in geographically diverse locations to safeguard against localized failures. This approach decreases risks and helps ensure business continuity in case of data loss or breaches.

Build secure applications with DigitalOcean

DigitalOcean offers a range of cloud products in a shared responsibility model framework to help developers and businesses of all sizes operate securely and efficiently. Whether you’re running applications or storing sensitive information, our products help ensure your data is secure at every stage. Explore how our offerings safeguard your cloud environment and elevate your data security:

• Droplets: Droplets are virtual machines designed to deploy applications. Data in transit is encrypted using HTTPS and TLS by default. Virtual disks stored on the hypervisor’s local storage are not encrypted at rest.

• DigitalOcean Kubernetes (DOKS): DOKS provides container orchestration for deploying your applications efficiently. Encryption is achieved by encrypting Kubernetes Secrets maintained in etcd at rest, along with TLS securing all traffic to and from the Kubernetes API.

• App Platform: App Platform is a fully managed platform for building and deploying your applications. Encryption occurs with managed database clusters using LUKS for data at rest, and HTTPS is used to serve web content, helping to ensure secure data in transit.

• Managed Databases: Managed Databases deliver fully managed database solutions with high availability. Encryption at rest is supported through LUKS, while TLS/SSL encrypts connections in transit, helping to secure traffic between your applications and databases. Backups are encrypted with a randomly generated key per file. These keys are further encrypted with an RSA key-encryption key pair and stored in the header section of each backup segment. The file encryption uses AES-256 in CTR mode and HMAC-SHA256 for integrity protection.

• Functions: Functions allow you to run code responding to events without provisioning servers. Encryption is implemented by storing user-sensitive data, such as Functions code, in encrypted volumes at rest and securing data in transit with HTTPS and TLS.

• Spaces: Spaces offer a simple and scalable object storage solution. Encryption is performed at rest, decreasing the risk of data breaches from malicious hardware access. You can improve privacy by using the s3cmd encrypt flag for additional data encryption. For data in transit, Spaces uses HTTPS and TLS by default, supporting secure transmission between Spaces and your application.

• Volumes: Volumes provide scalable storage solutions for your applications. Encryption is performed at rest, and you can create an encrypted file system on your Volume to help protect sensitive data from unauthorized access.

• Networking: Networking features facilitate secure communication within your cloud infrastructure. Encryption in transit is available through SSL passthrough or termination options, supporting secure traffic between the load balancer and backend Droplets.

Ready to protect your applications and data in the cloud? Sign up with DigitalOcean and experience the ease of cloud security.