Extensions to ciphertext-policy attribute-based encryption to support distributed environments

We present several extensions to the ciphertext-policy attribute-based encryption (CP-ABE) scheme, first introduced by Bethencourt, et. al. (2007), to support operation in a distributed environment with multiple attribute authorities. Unlike other efforts in creating a multi-authority attribute-based encryption schemes our extensions allow for each authority to be designated a subset of attributes and work independently in creating user keys (i.e. a user need only contact a single authority for their secret key). Additionally, we show that the presented extensions have a minimal impact on performance compared to standard CPABE and that both the performance of CP-ABE and our extensions can be improved by computing parts of the user and authority keys in parallel. We also discuss the use of CPABE in protecting data confidentiality in public cloud environments.