Every couple of months, we hear about cloud storage containers being left exposed, leaking millions of records. This shows that even when these systems appear encrypted, sensitive information could still be accessed in many cases. Protecting cloud data requires proper configuration, permissions, and access controls.
A system may be completely encrypted and still have security gaps. As a result, it is essential to understand that cloud storage encryption is more than a checkbox.
In this blog, we will look at how encryption actually works throughout the cloud storage lifecycle, and the questions you should ask before trusting a cloud provider with sensitive information.
How Does Cloud Storage Encryption Protect Your Data?
Cloud storage encryption converts readable data into ciphertext that cannot be understood without the right decryption key. It can protect files, databases, backups, and other information stored in cloud infrastructure.
When you upload a file, it may be encrypted before it reaches the cloud, or the cloud service may encrypt it before storing it. It is decrypted when an authorized user or application needs it.
When data is moving between your device and the cloud, transport layer security (TLS) helps protect it in transit by encrypting it. Encryption helps secure data from unauthorized access, but it does not replace access controls.
If an attacker breaches an account that already has permission to retrieve the data, the service may still provide the decrypted file.
For this reason, effective cloud security should combine encryption, identity management, access controls, and monitoring rather than relying on encryption alone.
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Also Read: What is AES encryption and how does it works to secure your data? |
How Encryption Protects Data in Transit and Data at Rest
Data in transit and data at rest are closely related, but they are designed to handle different security risks.
Encryption in Transit
Encryption in transit helps protect data while it moves across networks. It helps protect against man-in-the-middle attacks (MITM) and packet sniffing on public networks. It makes it difficult for attackers to read intercepted data.
Modern cloud architectures commonly use Transport Layer Security (TLS 1.3) to secure data as it moves between networks. TLS 1.3 uses ephemeral Diffie-Hellman key exchange to establish a secure connection. Ephemeral key exchange allows sessions to use fresh temporary session keys. Compromising a later session key does not allow an attacker to decrypt previously captured sessions.
Encryption at Rest
Encryption at rest protects data stored on disks, SSDs, or storage arrays. Cloud providers generally encrypt data before it is stored, so unauthorized access to the storage does not automatically expose the data in readable form.
But there is one limitation. When an authorized application needs to use the data, it may have to decrypt it in memory. At that point, the data may exist in readable form inside the application, where encryption at rest and encryption in transit do not directly protect it. This is why organizations handling highly sensitive data may use client-side encryption for additional protection.
Client-Side vs Server-Side Encryption: Who Holds the Key?
The main difference between client-side encryption and server-side encryption is where the data gets encrypted and who controls the encryption keys.
With server-side encryption, the cloud provider encrypts data before storing it and decrypts it when an authorized user or application requests it. It is convenient, scalable, and appropriate for many workloads. However, depending on the service and key configuration, the cloud provider may still handle the encryption and decryption process.
Client-side encryption changes how trust works. The data is encrypted before it reaches the cloud, so the provider stores and transmits only ciphertext, not the original plaintext.
The customer is responsible for managing the encryption keys, including key rotation, recovery, and integration with the application.
Cloud Storage Key Management and Envelope Encryption
Protecting the encryption keys is as important as encrypting the data. Cloud storage key management includes creating, storing, controlling access to, rotating, monitoring, and retiring encryption keys.
This is where envelope encryption can add another layer of protection.
Instead of using a key encryption key to encrypt every file directly, the system uses a data encryption key (DEK) to encrypt the data. That DEK is then encrypted using a key encryption key (KEK), which is typically protected through a dedicated key management service.
With this approach, data encryption keys remain protected, and key rotation becomes easier to manage. The systems that support key re-wrapping allow organizations to rotate the key encryption key (KEK) without re-encrypting the underlying data.
The important question businesses need to ask is not just whether their data is encrypted. The actual question is who controls the keys and who has access to them.
Can Your Cloud Storage Provider Access Your Data?
When you store sensitive files in the cloud, one important question is often overlooked: can the provider itself access your data? The answer depends on how the cloud storage service handles encryption and encryption keys.
In server-side encryption, the cloud provider manages the encryption and decryption process. Depending on the service and key configuration, it may be able to access plaintext data when an authorized request is made. On the other hand, zero-knowledge cloud storage offers a different level of control. In this cloud storage encryption model, the provider is designed not to access the customer’s plaintext data because the necessary encryption keys remain with the customer.
The provider can store and deliver your encrypted files, but it does not have the decryption keys needed to read them. This approach gives businesses greater control over data privacy. If your encryption key or recovery credentials are lost, the provider may not be able to help you regain access to your files.
This can be a good trade-off for sensitive data. However, businesses also need to consider how they will manage and recover data if something goes wrong.
How Cloud Storage Encryption Supports Compliance
For businesses in regulated industries, cloud storage encryption can be an important part of protecting sensitive data and cloud security compliance. Encryption can help businesses meet requirements for protecting sensitive data. But simply encrypting your data does not guarantee compliance on its own. Other security controls and processes are also required. These include access controls, logging, identity management, data retention policies, and incident response procedures.
Compliance is only one part of security. Even if a system meets regulatory requirements, it can still be vulnerable if it is not properly configured.
The Bottom Line
Cloud storage encryption consists of several layers of security, including encryption at rest, encryption in transit, key management, access controls, and control over who can access the plaintext data.
Before trusting a cloud provider with sensitive data, four questions can help you understand how a provider protects your data. Where is the data encrypted? Who controls the keys? Can the provider read the plaintext? And what happens if the keys are lost or compromised? These answers tell you more about your data’s security than simply seeing an encryption-enabled checkbox.
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FAQs
1. What is the difference between BYOK and HYOK in cloud key management?
Answer:Â BYOK (Bring Your Own Key):Â You create or control the encryption key and provide it to the cloud provider’s key management system. The provider can use the key to perform encryption and decryption operations according to your permissions and configuration.
HYOK (Hold Your Own Key):Â You keep the encryption key outside the cloud provider’s environment. The provider does not have direct access to the key, giving you greater control over who can decrypt the data.
2. Does using multiple cloud providers make key management harder?
Answer:Â Yes. Using multiple cloud providers can complicate key management because AWS KMS, Google Cloud KMS, and Azure Key Vault each have their own APIs, permission models, policies, and key-rotation processes.
3. Does deleting an encrypted file from cloud storage delete it permanently?
Answer:Â Deleting an encrypted file does not necessarily mean it is permanently removed. Cloud storage encryption protects stored data, while deletion depends on the provider’s backup, versioning, and retention policies.
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