2 SEMİNER : Dr. Mehmet Sabır KİRAZ, Dr. Osmanbey UZUNKOLTüm Etkinlikler
30
ARA

SEMİNER 1

Tarih: 30 Aralık 2015 Çarşamba, 
Saat: 10:00
Yer: E-2031

Konuşmacı:  Dr. Mehmet Sabır KİRAZ


Başlık: Verifiable Secret Sharing

 

Özet:"Secret sharing is an important primitive in cryptography. In general, a trusted dealer distributes the secret among the participants during the distribution protocol and the secret is recomputed by a subset of the participants during a reconstruction protocol. However, the root of trust is a challenge since one has to trust someone (which is a dealer in this case). Furthermore, a malicious dealer can distribute incorrect and inconsistent shares while the malicious participants may input incorrect shares during the reconstruction protocol. Therefore, it is important to avoid the trusted dealer and prevent malicious shareholders from computing incorrect output without being detected. The property of public verifiability allows that anybody (including the participants) can assure that their own shares are computed in a correct manner. We note that threshold cryptography is carried out with the secret sharing schemes.

In this talk, we will give a brief introduction to standard secret sharing schemes and then extend the general scheme to publicly verifiable secret sharing without using a trusted dealer. Finally, we present some threshold homomorphic encryption schemes and their practical implications in practice."

 

SEMİNER 2

Tarih: 30 Aralık 2015 Çarşamba, 
Saat: 11:00
Yer: E-2031

Konuşmacı:  Dr. Osmanbey UZUNKOL


Başlık: Arithmetical Secret Sharing

 

Özet: Abstract: Secret sharing is a cryptographic mechanism allowing to distribute shares among different parties. This is achieved by a trusted dealer in such a way that only authorized subset of parties can determine the secret. Unlike conventional cryptographic schemes, secret sharing schemes enable the user

to eliminate the root of trust problem. Furthermore, secret sharing has plenty of privacy preserving real-life applications ranging from access controls, oblivous transfers
to biometric authentication schemes. 
 
Cascudo, Cramer, and Xing  introduced arithmetic secret sharing schemes which are special quasi-threshold Fq-linear secret sharing schemes based on AG-codes. They can be used as the main algorithmic primitives in realizing information theoretically secure multi-party computation schemes (in particular, communication-efficient two-party cryptography) and verifiable secret sharing schemes.
 
In this talk, we discuss an asymptotic quantity, namely the torsion-limit, for
algebraic function fields over finite fields. Then we give some new bounds
for the torsion limit of certain towers of function fields over finite fields.
Furthermore, using some bounds on the torsion limits, we will give some recent
results regarding the construction of arithmetic secret sharing schemes. This is a
joint work with Seher Tutdere."