Spanning Backup for Office 365 offers Customer Managed Encryption Keys (also called Bring Your Own Key, Encryption Key Management, and Self Managed Encryption Keys). This option, available only at the time of installation, provides an additional layer of security for customers who need it.

Based on recommendations by the CSA (Cloud Security Alliance) and the requirements of CJIS
(Criminal Justice Information Services) Security Policy, it is a best practice for enterprise
organizations to use SaaS data protection solutions that support the self-management of encryption
keys.
Some of the organizational use cases for Spanning Backup for Office 365 Customer Managed
Encryption Keys include:

• Increased control over corporate data. Security teams want to be able to understand and
  control cloud providers’ level of access to their data, and they want the ability to suspend or
  shut off access at any time, thereby mitigating some risk related to data security. With
  Spanning Backup for Office 365’s new encryption key self-management feature,
  organizations can revoke the encryption keys used for their data stored in Spanning, giving
  them the control.
• Compliance and regulatory controls. Many organizations must meet client contractual
  compliance and regulatory requirements which include encryption key self-management.
  This is especially true for legal, financial, and consulting firms who are required to maintain
  full control over client data at all times.
• Internal policies and contracted policies. If an organization has corporate or legal policies
  directing the control of access to cloud and SaaS data, or if contracted partners or customers
  have these policies, Spanning Backup for Office 365 can now support those directives.
• Control and transparency regarding access to encrypted data. Encryption key self management provides data access transparency into how keys are used, as well as greater
  control via best practices in limiting key access.

If you are interested in this feature, read our installation guide: Spanning Backup for Office 365: Customer Managed Encryption Keys