• Publications
  • Influence
On Private Scalar Product Computation for Privacy-Preserving Data Mining
TLDR
This work shows that two of the private scalar product protocols, one of which was proposed in a leading data mining conference, are insecure and describes a provably private Scalar product protocol that is based on homomorphic encryption and can be used on massive datasets.
An Oblivious Transfer Protocol with Log-Squared Communication
  • H. Lipmaa
  • Computer Science, Mathematics
    ISC
  • 20 September 2005
We propose a one-round 1-out-of-n computationally-private information retrieval protocol for l-bit strings with low-degree polylogarithmic receiver-computation, linear sender-computation and
Efficient Algorithms for Computing Differential Properties of Addition
TLDR
This paper systematically study the differential properties of addition modulo 2n and derives log-time algorithms for most of the properties, including differential probability of addition, which represents a significant improvement over the best known algorithms.
Comments to NIST concerning AES Modes of Operations: CTR-Mode Encryption
TLDR
It is suggested that NIST, in standardizing AES modes of operation, should include CTR-mode encryption as one possibility for the next reasons, because it has significant efficiency advantages over the standard encryption modes without weakening the security.
Secure Equality and Greater-Than Tests with Sublinear Online Complexity
TLDR
This work obtains a greater-than protocol with sublinear online complexity in the arithmetic black-box model (O(c) rounds and O(c·l1/c) work online, with c=logl resulting in logarithmic online work).
On Diophantine Complexity and Statistical Zero-Knowledge Arguments
  • H. Lipmaa
  • Mathematics, Computer Science
    ASIACRYPT
  • 30 November 2003
TLDR
The outsourcing model for cryptographic protocols is proposed and communication-efficient versions of the Damgard-Jurik multi-candidate voting scheme and of the Lipmaa-Asokan-Niemi (b+1)st-price auction scheme that work in this model are proposed.
Secure Vickrey Auctions without Threshold Trust
TLDR
Two new cryptographic Vickrey auction schemes are proposed that involve, apart from the bidders and the seller S, an auction authority A so that unless S and A collude the outcome of auctions will be correct, and moreover, S will not get any information about the bids, while A will learn bid statistics.
Designated Verifier Signature Schemes: Attacks, New Security Notions and a New Construction
TLDR
A new and efficient designated-verifier signature scheme that is provably unforgeable under a tight reduction to the Decisional Diffie-Hellman problem in the non-programmable random oracle plus common reference string model is proposed.
Progression-Free Sets and Sublinear Pairing-Based Non-Interactive Zero-Knowledge Arguments
  • H. Lipmaa
  • Mathematics, Computer Science
    TCC
  • 19 March 2012
TLDR
This work reduces both the CRS length and the prover's computational complexity from quadratic to quasilinear in the circuit size of Groth's NIZK circuit satisfiability argument by using a recent construction of progression-free sets.
Cryptographically private support vector machines
TLDR
The new SVM classifiers are the first to be proven private according to the standard cryptographic definitions and it is shown how to use the encrypted classifications to privately estimate many properties of the data and the classifier.
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