Paper 2013/108

Unconditionally Secure and Universally Composable Commitments from Physical Assumptions

Ivan Damgard and Alessandra Scafuro


We present a constant-round unconditional black-box compiler that transforms any ideal (i.e., statistically-hiding and statistically-binding) straight-line extractable commitment scheme, into an extractable and equivocal commitment scheme, therefore yielding to UC-security [9]. We exemplify the usefulness of our compiler by providing two (constant-round) instantiations of ideal straight-line extractable commitment based on (malicious) PUFs [36] and stateless tamper-proof hardware tokens [26], therefore achieving the first unconditionally UC-secure commitment with malicious PUFs and stateless tokens, respectively. Our constructions are secure for adversaries creating arbitrarily malicious stateful PUFs/tokens. Previous results with malicious PUFs used either computational assumptions to achieve UC- secure commitments or were unconditionally secure but only in the indistinguishability sense [36]. Similarly, with stateless tokens, UC-secure commitments are known only under computational assumptions [13, 24, 15], while the (not UC) unconditional commitment scheme of [23] is secure only in a weaker model in which the adversary is not allowed to create stateful tokens. Besides allowing us to prove feasibility of unconditional UC-security with (malicious) PUFs and stateless tokens, our compiler can be instantiated with any ideal straight-line extractable commitment scheme, thus allowing the use of various setup assumptions which may better fit the application or the technology available.

Note: Updated related work.

Available format(s)
Publication info
A minor revision of an IACR publication in ASIACRYPT 2013
UChardware assumptionsunconditional securitycommitment scheme
Contact author(s)
alescafu @ gmail com
2015-03-03: last of 3 revisions
2013-02-27: received
See all versions
Short URL
Creative Commons Attribution


      author = {Ivan Damgard and Alessandra Scafuro},
      title = {Unconditionally Secure and Universally Composable Commitments from Physical Assumptions},
      howpublished = {Cryptology ePrint Archive, Paper 2013/108},
      year = {2013},
      note = {\url{}},
      url = {}
Note: In order to protect the privacy of readers, does not use cookies or embedded third party content.