Updatable Functional Encryption

  • Afonso Arriaga
  • Vincenzo Iovino
  • Qiang Tang
Conference paper
Part of the Lecture Notes in Computer Science book series (LNCS, volume 10311)


Functional encryption (FE) allows an authority to issue tokens associated with various functions, allowing the holder of some token for function f to learn only \(f(\mathsf {D})\) from a ciphertext that encrypts \(\mathsf {D}\). The standard approach is to model f as a circuit, which yields inefficient evaluations over large inputs. Here, we propose a new primitive that we call updatable functional encryption (UFE), where instead of circuits we deal with RAM programs, which are closer to how programs are expressed in von Neumann architecture. We impose strict efficiency constrains in that the run-time of a token \(\mathsf {\overline{P}}\) on ciphertext \(\mathsf {CT}\) is proportional to the run-time of its clear-form counterpart (program \(\mathsf {P}\) on memory \(\mathsf {D}\)) up to a polylogarithmic factor in the size of \(\mathsf {D}\), and we envision tokens that are capable to update the ciphertext, over which other tokens can be subsequently executed. We define a security notion for our primitive and propose a candidate construction from obfuscation, which serves as a starting point towards the realization of other schemes and contributes to the study on how to compute RAM programs over public-key encrypted data.


Updatable functional encryption RAM model Persistent memory 



The authors would like to thank Karol Zebrowski for his contribution to an earlier version of this work. Afonso Arriaga is supported by the National Research Fund, Luxembourg, under AFR Grant No. 5107187, and by the Doctoral School of Computer Science & Computer Engineering of the University of Luxembourg. Vincenzo Iovino is supported by the National Research Fund, Luxembourg. Qiang Tang is supported by a CORE (junior track) grant from the National Research Fund, Luxembourg.


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Copyright information

© Springer International Publishing AG 2017

Authors and Affiliations

  1. 1.SnT, University of LuxembourgLuxembourgLuxembourg

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