International Association for Cryptologic Research

International Association
for Cryptologic Research

CryptoDB

Siamak Fayyaz Shahandashti

Publications

Year
Venue
Title
2015
EPRINT
2015
EPRINT
2015
EPRINT
2014
EPRINT
2014
EPRINT
The SPEKE Protocol Revisited
Feng Hao Siamak Fayyaz Shahandashti
2008
PKC
2008
EPRINT
Attribute-Based Encryption with Key Cloning Protection
M. J. Hinek S. Jiang R. Safavi-Naini S. F. Shahandashti
In this work, we consider the problem of key cloning in attribute-based encryption schemes. We introduce a new type of attribute-based encryption scheme, called token-based attribute-based encryption, that provides strong deterrence for key cloning, in the sense that delegation of keys reveals some personal information about the user. We formalize the security requirements for such a scheme in terms of indistinguishability of the ciphertexts and two new security requirements which we call uncloneability and privacy-preserving. We construct a privacy-preserving uncloneable token-based attribute-based encryption scheme based on Cheung and Newport's ciphertext-policy attribute-based encryption scheme and prove the scheme satisfies the above three security requirements. We discuss our results and show directions for future research.
2007
EPRINT
Construction of Universal Designated-Verifier Signatures and Identity-Based Signatures from Standard Signatures
Siamak F Shahandshti Reihaneh Safavi-Naini
We give a generic construction of universal designated-verifier signature schemes from a large class C of signature schemes. Our constructions are comparable in terms of cost and size to their counterparts, while offering the following two main attractive features: Firstly, our constructions are provably non-delegatable beside being DV-unforgeable and non-transferable. Secondly, in our constructions, the signer and the designated verifier can choose different cryptographic settings of their own independently. We also propose a generic construction of identity-based signature schemes from any signature scheme in C and prove the construction secure against adaptive chosen message and identity attacks. We discuss possible extensions of our constructions to universal multi-designated-verifier signatures, hierarchical identity-based signatures, identity-based universal designated verifier signatures, and identity-based ring signatures from any signature in C.