US Patent 9544140 Multi-level key hierarchy for securing cloud-based data sets

A hierarchy is defined that includes encryption keys associated with different first and second levels of the hierarchy, where the second level includes fewer of the encryption keys than the first level. The encryption keys of the first level secure a plurality of data objects. The encryption keys of the first level are grouped into key groups that respectively include one or more of the encryption keys of the first level. The one or more of the encryption keys of the first level included in each of the key groups are secured with a respective one of the encryption keys of the second level.