DR Series Software 4.0 - Administrator Guide

Understanding Encryption at Rest

Data that resides in the DR Series system can be encrypted. When encryption is enabled, the DR Series system uses the Industry standard FIPS 140-2 compliant 256-bit Advanced Encryption Standard (AES) encryption algorithm for encrypting and decrypting user data. The content encryption key is managed by the key manager, which operates in either a Static mode or an Internal mode. In Static mode, a global, fixed key is used to encrypt all data. In internal mode, key lifecycle management is performed in which the keys are periodically rotated. The minimum key rotation period before the content encryption key can be rotated and a new key is generated is 7 days. This rotation period is user-configurable and can be specified in days. A user-defined passphrase is used to generate a pass phrase key, which is used to encrypt the content encryption keys. It is mandatory to define a passphrase to enable encryption. The system supports up to a limit of 1023 different content encryption keys. All streams of a data-store are encrypted or re-encrypted with the same content encryption key. DR Series system statistics report the amount of data encrypted and decrypted bytes consistently.

Encryption at Rest Terminology

This topic introduces and briefly defines some basic encryption at rest terminology used in the DR Series system documentation.

Term	Description
Passphrase	A passphrase is a sequence of words or other text used to control access to data, similar to a password in usage, but is generally longer for added security. In the DR Series system, the passphrase is user-defined and is used to generate a passphrase key that encrypts the file in which the content encryption keys are kept. The passphrase is a human readable key, which can be up to 255 bytes in length. It is mandatory to define a passphrase to enable encryption.
Content encryption key	The key used to encrypt the data. The content encryption key is managed by the key manager, which operates in either a static mode or an internal mode. The system supports up to a limit of 1023 different content encryption keys.
Key management mode	The mode of key lifecycle management as either static or internal.
Static mode	A global mode of key management in which a fixed key is used to encrypt all data.
Internal mode	A mode of key lifecycle management in which the keys are periodically generated and rotated. The minimum key rotation period before the content encryption key can be rotated and a new key is generated is 7 days. This rotation period is user-configurable and can be specified in days.

Encryption at Rest and DR Series Considerations

This topic describes key features and considerations of using Encryption at Rest in the DR Series system.

Key Management — In internal mode there is a maximum limit of 1023 keys. By default when encryption is enabled on the system, the key rotation period is set to 30 days. Users can later change the key rotation period from 7 days to 70 years, while configuring internal mode of encryption.

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Performance Impacts — Encryption should have minimal to zero impact on both backup and restore workflows.

It should also have no impact on the replication workflows.

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Replication — Encryption must be enabled on both the source and target DR Series systems to store encrypted data on the systems. This means that encrypted data on the source does not automatically imply that when it is replicated to the target it will be encrypted unless encryption is explicitly turned ‘ON’ on the target DR Series system.

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Seeding — Encryption must be enabled on both the source and target DR Series systems to store encrypted data on the systems. If seeding is configured for encryption, then the data will be re-encrypted and stored. When the data stream is imported onto the target from the seed device, the stream will be encrypted as per the target policy and stored.

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Security Considerations for Passphrase and Key Management —

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A passphrase is very important part of the encryption process on the DR Series system as the passphrase is used to encrypt the content encryption key or keys. If the passphrase is compromised or lost, the administrator should change it immediately so that the content encryption keys do not become vulnerable.

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The administrator should closely consider security requirements to drive the decision for selecting the mode of key management for the DR Series system.

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The Internal mode is more secure than the Static mode since the keys are periodically changed. Key rotation can be set to 7 days minimum.

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Key modes can be changed at any time during the lifetime of the DR Series system; however, changing the key mode is a significant operation to undertake as all encrypted data must be re-encrypted.

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Content encryption keys are stored in their encrypted form in a primary keystore, which is maintained on the same enclosure as the data-stores. For redundancy purposes, a backup copy of the primary keystore is stored on the system in the root partition, separate from the data-store partitions.