In one aspect, a data structure to be encrypted is received in a device, the data structure including content along with a statement of conditions under which the content may be decrypted. The data structure is encrypted using a symmetric key of a processor of the device. In another aspect, a data structure is decrypted using a processor symmetric key. A statement of conditions under which content in the data structure can be decrypted is obtained, and testing is performed as to whether the conditions are satisfied. The decrypted content is returned only if the conditions are satisfied.