TY - GEN
T1 - A Framework for UC-Secure Commitments from Publicly Computable Smooth Projective Hashing
AU - Abdolmaleki, Behzad
AU - Khoshakhlagh, Hamidreza
AU - Slamanig, Daniel
PY - 2019
Y1 - 2019
N2 - Hash proof systems or smooth projective hash functions (SPHFs) have been proposed by Cramer and Shoup (Eurocrypt’02) and can be seen as special type of zero-knowledge proof system for a language. While initially used to build efficient chosen-ciphertext secure public-key encryption, they found numerous applications in several other contexts. In this paper, we revisit the notion of SPHFs and introduce a new feature (a third mode of hashing) that allows to compute the hash value of an SPHF without having access to neither the witness nor the hashing key, but some additional auxiliary information. We call this new type publicly computable SPHFs (PC-SPHFs) and present a formal framework along with concrete instantiations from a large class of SPHFs. We then show that this new tool generically leads to commitment schemes that are secure against adaptive adversaries, assuming erasures in the Universal Composability (UC) framework, yielding the first UC secure commitments build from a single SPHF instance. Instantiating our PC-SPHF with an SPHF for labeled Cramer-Shoup encryption gives the currently most efficient non-interactive UC-secure commitment. Finally, we also discuss additional applications to information retrieval based on anonymous credentials being UC secure against adaptive adversaries.
AB - Hash proof systems or smooth projective hash functions (SPHFs) have been proposed by Cramer and Shoup (Eurocrypt’02) and can be seen as special type of zero-knowledge proof system for a language. While initially used to build efficient chosen-ciphertext secure public-key encryption, they found numerous applications in several other contexts. In this paper, we revisit the notion of SPHFs and introduce a new feature (a third mode of hashing) that allows to compute the hash value of an SPHF without having access to neither the witness nor the hashing key, but some additional auxiliary information. We call this new type publicly computable SPHFs (PC-SPHFs) and present a formal framework along with concrete instantiations from a large class of SPHFs. We then show that this new tool generically leads to commitment schemes that are secure against adaptive adversaries, assuming erasures in the Universal Composability (UC) framework, yielding the first UC secure commitments build from a single SPHF instance. Instantiating our PC-SPHF with an SPHF for labeled Cramer-Shoup encryption gives the currently most efficient non-interactive UC-secure commitment. Finally, we also discuss additional applications to information retrieval based on anonymous credentials being UC secure against adaptive adversaries.
UR - http://www.scopus.com/inward/record.url?scp=85077009196&partnerID=8YFLogxK
U2 - 10.1007/978-3-030-35199-1_1
DO - 10.1007/978-3-030-35199-1_1
M3 - Article in proceedings
AN - SCOPUS:85077009196
SN - 9783030351984
T3 - Lecture Notes in Computer Science
SP - 1
EP - 21
BT - Cryptography and Coding - 17th IMA International Conference, IMACC 2019, Proceedings
A2 - Albrecht, Martin
PB - Springer
T2 - 17th IMA International Conference on Cryptography and Coding, IMACC 2019
Y2 - 16 December 2019 through 18 December 2019
ER -