To address this problem, we develop new techniques for ABE that split the computation for these algorithms into two phases: a preparation phase that does the vast majority of the work to encrypt a message or create a secret key *before* it knows the message or the attribute list/access control policy that will be used (or even the size of the list or policy). A second phase can then rapidly assemble an ABE ciphertext or key when the specifics become known. This concept is sometimes called ``online/offline'' encryption when only the message is unknown during the preparation phase; we note that the addition of unknown attribute lists and access policies makes ABE significantly more challenging.
One motivating application for this technology is mobile devices: the preparation work can be performed while the phone is plugged into a power source, then it can later rapidly perform ABE operations on the move without significantly draining the battery.Category / Keywords: public-key cryptography / attribute-based encryption, online/offline, preprocessing Original Publication (with minor differences): IACR-PKC-2014 Date: received 7 Jan 2014 Contact author: susan at cs jhu edu Available format(s): PDF | BibTeX Citation Note: This is the full version of the work to appear in PKC 2014. Version: 20140108:174948 (All versions of this report) Short URL: ia.cr/2014/021 Discussion forum: Show discussion | Start new discussion