Chethan Kamath
Institute of Science and Technology Austria
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Publication
Featured researches published by Chethan Kamath.
security and cryptography for networks | 2016
Georg Fuchsbauer; Christian Hanser; Chethan Kamath; Daniel Slamanig
At Crypto 2015 Fuchsbauer, Hanser and Slamanig FHS presented the first standard-model construction of efficient round-optimal blind signatures that does not require complexity leveraging. It is conceptually simple and builds on the primitive of structure-preserving signatures on equivalence classes SPS-EQ. FHS prove the unforgeability of their scheme assuming EUF-CMA security of the SPS-EQ scheme and hardness of a version of the DH inversion problem. Blindness under adversarially chosen keys is proven under an interactive variant of the DDH assumption. We propose a variant of their scheme whose blindness can be proven under a non-interactive assumption, namely a variant of the bilinear DDH assumption. We moreover prove its unforgeability assuming only unforgeability of the underlying SPS-EQ but no additional assumptions as needed for the FHS scheme.
international conference on information security and cryptology | 2012
Sanjit Chatterjee; Chethan Kamath; Vikas Kumar
In Africacrypt 2009, Galindo-Garcia [12] proposed a lightweight identity-based signature (IBS) scheme based on the Schnorr signature. The construction is simple and claimed to be the most efficient IBS till date. The security is based on the discrete-log assumption and the security argument consists of two reductions:
international cryptology conference | 2017
Zahra Jafargholi; Chethan Kamath; Karen Klein; Ilan Komargodski; Krzysztof Pietrzak; Daniel Wichs
\mathcal{B}_{1}
Algorithmica | 2016
Sanjit Chatterjee; Chethan Kamath
and
Advances in Mathematics of Communications | 2018
Sanjit Chatterjee; Chethan Kamath; Vikas Kumar
\mathcal{B}_{2}
Space | 2013
Sanjit Chatterjee; Chethan Kamath
, both of which use the multiple-forking lemma [4] to solve the discrete-log problem (DLP). In this work, we revisit the security argument given in [12]. Our contributions are two fold: (i) we identify several problems in the original argument and (ii) we provide a detailed new security argument which allows significantly tighter reductions. In particular, we show that the reduction
international cryptology conference | 2016
Joël Alwen; Binyi Chen; Chethan Kamath; Vladimir Kolmogorov; Krzysztof Pietrzak; Stefano Tessaro
\mathcal{B}_{1}
IACR Cryptology ePrint Archive | 2016
Joël Alwen; Peter Gazi; Chethan Kamath; Karen Klein; Georg Osang; Krzysztof Pietrzak; Leonid Reyzin; Michal Rolinek; Michal Rybár
in [12] fails in the standard security model for IBS [1], while the reduction
computer and communications security | 2018
Joël Alwen; Peter Gazi; Chethan Kamath; Karen Klein; Georg Osang; Krzysztof Pietrzak; Lenoid Reyzin; Michal Rolinek; Michal Rybár
\mathcal{B}_{2}
IACR Cryptology ePrint Archive | 2018
Georg Fuchsbauer; Chethan Kamath; Karen Klein; Krzysztof Pietrzak
is incomplete. To remedy these problems, we adopt a two-pronged approach. First, we sketch ways to fill the gaps by making minimal changes to the structure of the original security argument; then, we provide a new security argument. The new argument consists of three reductions: