Cryptology ePrint Archive: Report 2016/934

Cryptography with Updates

Prabhanjan Ananth and Aloni Cohen and Abhishek Jain

Abstract: Starting with the work of Bellare, Goldreich and Goldwasser [CRYPTO'94], a rich line of work has studied the design of updatable cryptographic primitives. For example, in an updatable signature scheme, it is possible to efficiently transform a signature over a message into a signature over a related message without recomputing a fresh signature.

In this work, we continue this line of research, and perform a systematic study of updatable cryptography. We take a unified approach towards adding updatability features to recently studied cryptographic objects such as attribute-based encryption, functional encryption, witness encryption, indistinguishability obfuscation, and many others that support non-interactive computation over inputs. We, in fact, go further and extend our approach to classical protocols such as zero-knowledge proofs and secure multiparty computation.

To accomplish this goal, we introduce a new notion of updatable randomized encodings that extends the standard notion of randomized encodings to incorporate updatability features. We show that updatable randomized encodings can be used to generically transform cryptographic primitives to their updatable counterparts.

We provide various definitions and constructions of updatable randomized encodings based on varying assumptions, ranging from one-way functions to compact functional encryption.

Category / Keywords: Updatable Cryptography, Randomized Encodings

Date: received 28 Sep 2016

Contact author: prabhanjan va at gmail com

Available format(s): PDF | BibTeX Citation

Version: 20160929:103248 (All versions of this report)

Short URL: ia.cr/2016/934

Discussion forum: Show discussion | Start new discussion


[ Cryptology ePrint archive ]