2:30-3:30 pm

Room 8405, CUNY Graduate Center

365 Fifth Avenue at 34th Street

Room Peirce 220, Stevens Institute of Technology

Hoboken, NJ

directions

Security seminars at Stevens

**October 3, Graduate Center**: Vladimir Shpilrain (The City College of New
York), *Authentication schemes*

**Abstract: ** In the first part of my talk, I will describe a couple of general
ways of constructing Feige-Fiat-Shamir-like
authentication schemes from actions of a semigroup on a set, without
exploiting any specific algebraic properties of the set acted upon.
Then I will give several concrete realizations of this general
idea, and in particular, describe several authentication schemes
where both forgery (a.k.a. impersonation) and recovering the
prover's long-term private key are NP-hard. Computationally hard
problems that can be employed in these realizations include Graph
Homomorphism, Graph Colorability, Diophantine Problem, and many
others.

In the second part of the talk, I will describe an authentication
scheme, based on an altogether different idea, where forgery is
apparently infeasible without finding the prover's long-term private
key.

This is joint work with Dima Grigoriev.

**October 17, Graduate Center**: Alex Myasnikov (Stevens Institute),
*Cryptanalysis of the Anshel-Anshel-Goldfeld-Lemieux key agreement protocol*

**Abstract: ** The Anshel-Anshel-Goldfeld-Lemieux (abbreviated AAGL) key agreement
protocol is proposed to be used on low-cost platforms that constrain the use of
computational resources. The core of the protocol is the concept of an Algebraic Eraser (abbreviated
AE) which is claimed to be a suitable
primitive for use within lightweight cryptography. The underlying
motivation for AAGL protocol is the
need to secure networks which deploy Radio Frequency Identification
(RFID) tags used for identification, authentication, tracing and point-of-sale applications.

In this talk we revisit the computational problem on which AE
relies and heuristically analyze its
hardness. We show that for proposed parameter values it is
impossible to instantiate the secure protocol.
To be more precise, in 100% of randomly generated instances of the
protocol we were able to find a secret conjugator z generated by the TTP algorithm (part of AAGL protocol).

**October 31, Graduate Center**: Ben Fine (Fairfield University),
*Challenge-Response Password Security Using Combinatorial Group Theory*

**November 7, Graduate Center**: Alexander Ushakov (Stevens Institute of
Technology), *The conjugacy problem in Grigorchuk's group*

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