Encryption in the Cloud: An Overview

In this post we will look at how to secure your AWS solution data using encryption (if you need a primer on encryption here is a good one). We will also look at some of various services from AWS and other third party vendors that will help you not only encrypt your data, but take care of more problematic issues such as managing keys.

Why Encryption

Whether it’s Intellectual Property (IP) or simply just user names and passwords, your data is important to you and your organization. So, keeping it safe is important. Although hardening your network, operating systems, access management and other steps can greatly reduce the chance of being compromised, the cold hard reality is that, at some point, in your companies’ existence that data will be compromised. So, assuming that you will be compromised is one major reason we need to encrypt data. Another major reason is the likelihood of accidental or purposeful inappropriate data access and leakage by employees which, depending on what studies you look at, is perhaps the largest reason for data exposure. Regardless of the reason or vector, you never want to expose important data unintentionally, and for this reason encrypting your sensitive information is fundamental to basic security.

Three states of data

Generally we classify data as having three distinct states:

• Data at rest, such as when your data is in files on a drive or data in a database
• Data in motion, such as web requests going over the Internet via port 80
• Data in use, which is generally data in RAM or data being used by the CPU

In general, the most at risk data is data at rest and data in motion, both of which are reasonably straight forward to secure in the cloud, although their implementation needs to be carefully managed to maintain strong security.

What to encrypt and what not to

Most security people would love to encrypt anything and everything all the time, but encryption creates numerous real or potential problems. The first of these is that encryption is often computationally expensive and can consume CPU resources, especially when you’re constantly encrypting and decrypting data. Indeed, this has been one of the main reasons why vendors like Google did not encrypt all search traffic until recently. Another reason people often do not widely apply encryption is that it creates potential system administration and support issues since, depending on the encryption approach you take, you can create complex issues for managing your keys. Indeed, even the most simple encryption systems, such as encrypting a whole drive with a single key, requires strong key management in order to be effective. This can create added expense and resource costs since organizations have to implement human and automated systems to manage and control keys. While there are many more reasons people do not widely implement encryption, the reality is that you usually have to make determinations on what to encrypt. Most organizations follow a process for deciding on what to encrypt in the following manner:

1- What data must be private? This might be Personal Identifying Information, credit card numbers, or the like that is required to be private for compliances reasons such as PCI or FISMA.

2- What level of sensitivity is this data? Some data such as PII often has federal data security requirements that are dictated by what industry you are in. For example, in health care HIPPA requirements dictate the minimum level of encryption you must use (see here for an example). Other data might require further encryption levels and controls.

3-What is the data’s value to my business? This is a tricky one. Many companies decide they need little to no encryption for data assuming it is not important, such as their user’s email addresses. Then they get compromised and their users spammed and have their identities stolen potentially causing real legal damages to the company or destroying their reputation. Depending on your business and your business model, even if you are not required to encrypt your data, you may want to in order to protect your company, its reputation or the brand.

4-What is the performance cost of using a specific encryption approach to data and how will it affect my business?

These high level steps will give you a sense of what you should encrypt or need to encrypt and how to encrypt it. Item 4 is specifically important, in that while it might be nice to encrypt all your data with 4096 Elliptic Curve encryption keys, this will most likely create too high of a computational load and bottle neck on any high transactional application, such as an e-commerce store, to be practical to implement. This takes us to our next topic, which is choosing encryption approaches.

Encryption choices in the cloud for Data at Rest

Generally there are two major choices to make when encrypting data, especially data at rest. These are:

1 – Encrypt only key sensitive data such as logins, passwords, social security and similar data.

2 – Encrypt everything.

As we have pointed out, while encrypting everything would be nice, there are a lot of potential issues with this. In some cases, however, such as backing up data to S3 or Glacier for long term storage, it might be a total no brainer. More typically, thought, numerous factors weigh in.

Another choice you have to make with cloud solutions is where you will do your encryption. This needs to be influenced by your specific application requirements, business requirements, and the like. When deploying cloud solutions you also need think about how you interact with your cloud system. While you might be using a secure VPN from your office or home, you need to think about encrypting your data on your client systems that interact with your AWS-based system. For example, if you upload data to your system, don’t just trust in SSL. You should make sure you use the same level of encryption you use on AWS on your home or office systems. AWS allows you to support server side encryption, client side encryption, or server side encryption with the ability to use your own keys that you manage on the client. This is an important and recent feature - the ability to use your own - since various federal and business security standards require you to maintain possession of your own cryptographic keys. That being said, managing your own keys can be difficult to do well. AWS offers some help with Hardware Security Modules with their CloudHSM. Another route is the multiple vendors that offer services to help you manager enterprise key management such as CloudCipher.

Data in Motion

Depending on your application users, you may need to send sensitive data to your AWS instances without being able to encrypt the data on their side first. An example is when creating a membership to your site where you want to protect their password or during an e-commerce transition were you want to protect credit card and other information. In these cases, instead of using regular HTTP, you want to use HTTP Secure protocol or HTTPS. HTTPS makes use of SSL/TLS, an encryption protocol for data in motion, to encrypt data as it travels over the network. While HTTPS can affect performance of web servers or network applications, its benefits often far outweigh the negligible overheard it creates. Indeed, AWS makes extensive use of SSL/TLS to protect network traffic between you and AWS and between various AWS services. As such, you should make sure to protect any data, in motion, with a reputable SSL certificate. Also, if you are new to using SSL for your application, you should strongly consider reviewing OWASP’s excellent cheat sheet on SSL. Finally, as stated earlier, don’t just trust in SSL when sharing sensitive data. The best practice is to hash or encrypt any and all sensitive data when possible, since attackers can sometimes, and have, compromised SSL security.

Data in Use

Data in use encryption, the encryption of data when it’s being used in RAM or by the CPU, is generally a special case in encryption that is mostly ignored in modern hosted applications. This is because it is very difficult and often not considered worth the effort for systems hosted on the premise. Cloud vendors though, like AWS, create special considerations for customers, since the cloud vendor controls have physical access to your computer. This can potentially allow a malicious actor with access to that hardware to circumvent data encryption by accessing a system’s physical memory to steal encryption keys or steal data that is in plain text in memory. As of 2012, the Cloud Security Alliance has started to recommend the use of encryption for data in use as a best practice; see here. For this reason, a number of vendors have started offering data in use encryption specifically for cloud systems like AWS. This should be considered only for systems or applications that have the most extreme security requirements such as national security. Companies like Privatecore and Vaultive currently offer services that allow you to encrypt your data even from your service provider.

Summary

Encryption and its proper use is a huge subject and we have only been able to lightly touch on the topic. Implementing encryption is rarely easy, yet AWS takes much of the difficult out of encryption by providing a number of services for you. That being said, being aware of what your risks are, how encryption can help mitigate those risks, what specific types of encryption to use, and how it will affect your solution requires continued study. To help you with this, some useful reference material has been provided.

Encryption References

OWASP: Guide to Cryptography

OWASP: Password Storage Cheat Sheet

OWASP: Cryptographic Storage Cheat Sheet

Best Practices: Encryption Technology

Cloud Security Alliance: Implementation Guidance, Category 8: Encryption

AWS Security Best Practices

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About the author

Robi Sen, CSO at Department 13, is an experienced inventor, serial entrepreneur, and futurist whose dynamic twenty-plus year career in technology, engineering, and research has led him to work on cutting edge projects for DARPA, TSWG, SOCOM, RRTO, NASA, DOE, and the DOD. Robi also has extensive experience in the commercial space, including the co-creation of several successful start-up companies. He has worked with companies such as UnderArmour, Sony, CISCO, IBM, and many others to help build out new products and services. Robi specializes in bringing his unique vision and thought process to difficult and complex problems allowing companies and organizations to find innovative solutions that they can rapidly operationalize or go to market with.