Encryption in the Cloud: Securing Data and Keys

As a security professional with over years of experience, I have seen the landscape of data protection evolve dramatically. In the early days of cloud computing, there were many concerns about storing sensitive data with third-party providers. Could it really be kept secure?

What we’ve learned is that while the cloud introduces new attack surfaces, it also allows improved security controls when applied correctly — especially powerful encryption. In this article, I aim to demystify encryption in the cloud and share best practices I’ve learned for securing critical data and keys.

The Role of Encryption

At its core, encryption is about scrambling data so that only authorized parties can access it. Modern algorithms use complex mathematical transformations to convert plaintext data into ciphertext that looks meaningless. The main purpose is to prevent unauthorized access in the event your infrastructure and defenses are compromised.

When data is properly encrypted, attackers should not be able to extract any usable information from it. They might delete it or hold it for ransom, but the encrypted contents remain theoretically secure.

For cloud environments especially, encryption serves to protect your data while it’s stored on someone else’s hardware. Infrastructure admins at your cloud provider should never be able to access the decrypted content — only you can unlock it with the encryption keys.

Choosing Encryption Strategies

There are many encryption standards, protocols, APIs, libraries, and tools available today, so navigating the options can seem overwhelming. Fundamentally, you need to encrypt your data in transit and at rest:

• Data in transit: This refers to any data flowing over a network, whether between cloud services or from users to cloud applications. The TLS encryption protocol secures data in transit and should be used for all connections.
• Data at rest: For data persisted to cloud storage, disk and file encryption protect against unauthorized access. Cloud services make it easy to enable encryption at rest for databases, object storage, bulk storage volumes, and more.

Within these categories, you can opt for application-level encryption where apps and services handle scrambling sensitive data fields or more broad encryption at the disk and file system level. Both application encryption and disk/file encryption have benefits depending on your needs and architecture.

Additionally, some key considerations when selecting cloud encryption strategies include:

• Encryption key management: You can manage keys yourself or use the cloud provider’s key management system. Both have pros and cons related to control vs convenience.
• Tokenization: This substitutes sensitive data with randomized tokens that have no extrinsic value. Used properly, it can enhance security further by removing the need to handle real data or encryption keys.
• HashiCorp Vault: For advanced encryption key lifecycle management, Vault is an industry-leading open source tool.

By approaching encryption methodically across data lifecycles and narrowing options, you can choose the right standards and tools for your risk profile.

Encrypting Data in the Cloud

Once you have a strategy, putting encryption into practice takes planning and precision. Luckily, reputable cloud providers make it straightforward to implement encryption in ways that meet common compliance requirements.

Here are some best practices to secure data through encryption in the cloud:

1. Classify your data Not all data requires the same levels of protection. Assess the sensitivity, business impact, and regulations around each data source. Then tailor your encryption models appropriately.
2. Encrypt data in transit Implement TLS for all connections and data transfers. TLS uses ephemeral keys to provide session encryption between two endpoints. With services like Elastic Load Balancing, Amazon VPC, and Azure Application Gateway, enabling TLS is a checkbox in a configuration menu.
3. Evaluate application-level encryption options For data that will undergo significant processing, encrypting specific data fields at the application layer makes sense. This allows apps to operate on the decrypted data temporarily while it’s in context, while shielding sensitive attributes.
4. Enable disk and file encryption For data that will simply be stored or archived, disk-level and file system-level encryption provide robust protection without application complexity. Options like Amazon’s EBS encryption or Azure Disk Encryption make full disk encryption easy to apply.
5. Store encryption keys securely Private keys used for decryption must be protected carefully from compromise! For the highest security, keep keys in secure hardware like AWS CloudHSM or Azure Key Vault. Multi-tenant SaaS products also handle key management securely.
6. Rotate keys periodically To reduce the risks from a compromised key, generate new keys and retire old ones on a 90-day basis or less for extremely sensitive data.
7. Enforce access control diligently Even encrypted data should follow least privilege access policies so that decrypted content stays protected. Remember access requirements during key provisioning as well.
8. Validate compliance needs Stay current on standards like PCI DSS, HIPAA, GDPR, and similar frameworks. Build auditable evidence of strong data encryption and key management tailored to your compliance obligations.

By systematically encrypting data in the cloud, you can retain control and security even when relying on third-party infrastructure.

Managing Encryption Keys

Encryption keys represent the “keys to the kingdom” when it comes to access, making their lifecycle management critical. Mistakes here can lead to irrecoverable data or unauthorized access.

All keys should be generated via robust cryptographic processes that leverage hardware technologies like Intel’s Secure Key instructions. Underlying entropy sources must provide sufficient randomness to prevent prediction of new keys.

Here are my top tips for managing encryption keys in the cloud:

● Automate generation and rotation of keys following defined schedules for each data type, allowing sufficient time for encryption progress between rotations.

● To deliver keys to processing engines securely, leverage internal secrets APIs, key hierarchies, and short-lived access tokens.

● Store keys externally in secure hardware modules or managed services like Azure Key Vault and AWS KMS whenever possible. This protects against unauthorized access even when your cloud account is compromised.

● Construct access policies, grants, and permissions purposefully, evaluating infrastructure principals, users, groups, and application needs independently.

● Retire and revoke obsolete keys promptly when they are no longer needed to shrink your blast radius. Destroy deactivated keys from persistent storage.
● Log key usage comprehensively to records decryption events and attempts for auditing. Centralize logs into systems like the ELK stack.

● Develop backups and key recovery procedures so that losing keys does not equate to losing data access entirely when disasters strike.
● Regularly verify that old keys can no longer decrypt to confirm crypto periods and key revocation are working properly.

While encryption secures the contents of data, encryption keys themselves must also stay protected for your defenses to function. By handling keys carefully and reducing their exposure to risk, you safeguard access.

Monitoring & Auditing Encryption

To provide evidence that encryption and key management controls function properly in practice, auditing and monitoring becomes essential.

Ideally, processes should log events like key state changes, cryptographic operations, and access attempts. Central log analysis tools can spot anomalies, collect audit evidence, and alert on issues.

Here are some best practices I recommend for monitoring encryption:

• Send logs to a SIEM tool like Splunk or IBM QRadar to correlate behaviors across systems.
• Ingest logs into analytics platforms like the ELK stack to query events and uncover hidden patterns.
• Configure alerts for security events related to encryption keys and data access — for example, an abnormal number of decryption failures on a database.
• Report metrics on encryption progress across services and track the lifespans/rotation periods for keys over time.
• Randomly sample recovered plaintext data at least annually to check for flaws in encryption processes.
• Frequently check user access logs and group/policy changes to watch for permissions creep.
• Run scheduled reports that validate suspected encryption levels across storage volumes based on a sample of files.
• Monitor for abnormal application errors indicating misconfigured encryption or corrupted ciphertexts.

Proactive monitoring through tooling, analytics, and scheduled audits allows you to get ahead of underlying flaws or misconfigurations. This protects access and integrity over the long term while compiling records for compliance needs.

Adjusting Encryption as Needs Evolve

Even with extensive initial planning, your ideal encryption configurations are likely to diverge from reality over time as an organization’s applications and infrastructure evolve dynamically. Expect to revisit and refine aspects of your encryption strategy frequently.

Some drivers of change include:

• Adding support for new data streams that need confidentiality
• Transitioning applications into new regions or clouds
• Deprecating aging encryption algorithms as computational power advances
• Responding to heightened threats and exploiting vulnerabilities
• Accommodating mergers, acquisitions and divestitures
• Preparing systems for emerging compliance standards

Evolving business priorities will prompt changes as well. Launching new digital products, optimizing costs, or consolidating multiple cloud environments can all necessitate encryption model changes to realign with strategic goals.

By revisiting the balance of encryption burdens across providers, applications, and hardware environments periodically, you can unlock more security value from encryption while retiring unnecessary complexity that slows development velocity.

Closing Thoughts

In closing, encrypting data in the cloud definitively strengthens control and security if implemented diligently across architectures. However, it is certainly not the only control required to secure cloud environments comprehensively.

Well-rounded cloud security also requires:

• Carefully configured identity and access management
• Extensive logging with central analysis
• Web application protections like WAFs
• Endpoint security on client devices
• Ongoing vulnerability management
• And much more!

Like any security tool, encryption plays an important role but does not represent a silver bullet. As part of a defense-in-depth strategy applied consistently across data lifecycles, purposeful encryption unlocks substantial safety and compliance benefits.

I hope these experiences and best practices help demystify encryption specifics for the cloud while providing a blueprint to secure critical data and keys. Reach out anytime if you need assistance tailoring robust encryption models or navigating related compliance obligations for your organization. Here’s to building safer systems!