Is there more to encryption key management than just storing my encryption keys?
There is far more to encryption key management than just storing the encryption key somewhere… as it turns out, there is a whole encryption key lifecycle that is (or should be) handled by a certified encryption key management solution. Generally, a key storage device only provides storage of the encryption key, and you need to create the key elsewhere. Also, just storing your encryption keys “somewhere” doesn’t work very well for compliance regulations. With an encryption key manager, there is a whole set of management capabilities and a suite of functions that provide dual control, create separation of duties, implement two factor authentication, generate system logs, and perform audit activities, along with managing the key life cycle (including storage). There is a very real need, and very specific guidelines that require you to store and manage your encryption keys away from the data that they protect.
The Encryption Key Life Cycle
Beyond storing the encryption key, a cryptographic key manager manages the entire key life cycle. Some of the most important functions the key management administrator performs are the actual creation and management of the encryption keys. The keys are generated and stored securely and then go through the full cycle to become active, go into use, expire, retire (post-activation), and then be backed up in escrow, and then deleted (the “destruction” phase). Let’s take a closer look at the phases of a key life cycle and what a key management solution should do during these phases:
Key Generation & Pre-Activation:
First, the encryption key is created and stored on the key management server (which can be a hardware security module (HSM), virtual environment (VMware) or a true cloud instance). The key can be created by a sole administrator or through dual control by two administrators. The key manager produces the AES key through the use of a cryptographically secure random bit generator and stores the key, along with all it’s attributes, into the key storage database (which is also encrypted). The attributes stored with the key include its name, activation date, size, instance, the ability for the key to be deleted, as well as its rollover, mirroring, and key access attributes. The key can be activated upon its creation or set to be activated automatically or manually at a later time. The key manager should also be able to create keys of three different sizes: 128, 192, or 256-bit. The encryption key manager should also track current and past instances, or versions, of the encryption key. You can also choose whether or not the key can be deleted, mirrored to a failover unit, and by which users or groups it can be accessed. Your key manager should allow the administrator to change many of the key’s attributes at any time.
Key Activation through Post-Activation:
The key manager should allow an activated key to be retrieved by authorized systems and users for encryption or decryption processes. It should also seamlessly manage current and past instances of the encryption key. For example, if a key is rolled every year and the version is updated, then the key manager should retain previous versions of the key but dispense only the current instance for encryption processes. Previous versions can still be retrieved in order to decrypt data encrypted with such versions of the key. The key manager should use transport layer security (TLS) connections to securely deliver the encryption key to the system and user requesting it, which prevents the key from being compromised. The encryption key manager will also expire the key either through a previously established schedule or manually by an administrator.
Key Expiration & Revocation (Escrow):
An administrator should be able to use the key manager to revoke or deactivate a key so that it is no longer used for encryption requests. In certain cases the key can continue to be used to decrypt data previously encrypted with it, like old backups, but even that can be restricted. A revoked key can, if needed, be reactivated by an administrator, although this would be more an exception to the rule than common practice.
If a key is no longer in use or if it has somehow been compromised, an administrator can choose to delete the key entirely from the key storage database of the encryption key manager. The key manager will remove it and all its instances, or just certain instances, completely and make the recovery of that key impossible (other than through a restore from a backup image). This should be available as an option if sensitive data is compromised in its encrypted state. If the key is deleted, the compromised data will be completely secure since it would be impossible to recreate the encryption key for that data.
This encryption key life cycle, which is defined by the National Institute of Standards and Technology (NIST), also requires that a crypto period be defined for each key. A crypto period is the length of time that a key should be used and is determined by a number of factors based on how much data is being protected and how sensitive that data is. While NIST has defined and provided some parameters on how to establish crypto periods (see special publications 800-57 - there are 3 parts) and provided guidance on best practices. Each key management administrator needs to determine how long a particular encryption key should be actively used before it is rotated or retired.
These are a few of the factors that go into establishing the crypto period for a key (which maybe a few days or weeks or longer up to one or two years it really depends on the data that you're trying to protect):
- How is the data being used
- How much data is there
- How sensitive is the data
- How much damage will be done when the data is exposed or the keys are lost
You can see that there is a significant difference between a key storage device and an encryption key management solution. Remember to always look for NIST validated and FIPS 140-2 compliant solutions to meet compliance requirements and follow security best practices!
To learn more about encryption key management download our ebook on Encryption Key Management Simplified.