Publications de László Czap | EPFL Graph Search

An LP Characterization of the Secret-message Capacity of Three Erasure Networks With Feedback

Suhas Diggavi, Christina Fragouli, László Czap, Vinod Malathidevi Prabhakaran

This paper presents exact capacity characterizations for the case, when a principal, Alice, wants to securely send a message to another principal, Bob, over three network configurations: the parallel edges network, the V-network, and the triangle network. ...

Ieee-Inst Electrical Electronics Engineers Inc2016

Creating Secrets Out Of Packet Erasures

Christina Fragouli, Aikaterini Argyraki, Iris Safaka, László Czap

We present protocols for creating pairwise secrets between nodes in a wireless network, so that these secrets are secure from an eavesdropper, Eve, with unbounded computational and memory capabilities, but with limited network presence. We first present a ...

Ieee-Inst Electrical Electronics Engineers Inc2016

Secret Communication Over Broadcast Erasure Channels With State-Feedback

Suhas Diggavi, Christina Fragouli, László Czap, Vinod Malathidevi Prabhakaran

We consider a 1-to-K communication scenario, where a source transmits private messages to K receivers through a broadcast erasure channel, and the receivers feedback strictly, causally, and publicly their channel states after each transmission. We explore ...

Ieee-Inst Electrical Electronics Engineers Inc2015

Secure Network Coding With Erasures and Feedback

Suhas Diggavi, Christina Fragouli, László Czap, Vinod Malathidevi Prabhakaran

Secure network coding assumes that the underlying network channels are error-free; thus, if our channels introduce errors, we need to first apply a channel code to correct them, and then build security on top of the resulting error-free network. In this pa ...

Ieee-Inst Electrical Electronics Engineers Inc2015

Triangle Network Secrecy

Suhas Diggavi, Christina Fragouli, László Czap, Vinod Malathidevi Prabhakaran

We characterize the secret message capacity of the triangle network, that consists of a source, a relay and a destination connected through orthogonal erasure channels. A passive eavesdropper, Eve, wiretaps any one of the three channels. The source and the ...

2014

Secure Communication in Erasure Networks with State-feedback

László Czap

The security and efficiency of communication are two of the main concerns for networks of today and the future. Our understanding of how to efficiently send information over various channels and networks has significantly increased in the past decade (see ...

EPFL2014

Securing Broadcast Against Dishonest Receivers

Suhas Diggavi, Christina Fragouli, László Czap, Vinod Malathidevi Prabhakaran

Consider a sender, Alice, who wants to transmit private messages to two receivers, Bob and Calvin, using unreliable wireless broadcast transmissions and short public feedback from Bob and Calvin. In [1], we assumed that Bob and Calvin provide honest feedba ...

IEEE2013

Exploiting Common Randomness: a Resource for Network Secrecy

Suhas Diggavi, László Czap, Vinod Malathidevi Prabhakaran

We investigate the problem of secure communication in a simple network with three communicating parties, two distributed sources who communicate over orthogonal channels to one destination node. The cooperation between the sources is restricted to a rate l ...

2013

Secure Network Coding with Erasures and Feedback

Suhas Diggavi, Christina Fragouli, László Czap, Vinod Malathidevi Prabhakaran

Secure network coding assumes that the underlying network links are lossless, thus it can be applied over lossy networks after channel error correction. Yet it is well known that channel losses, such as packet erasures, can be constructively used for secre ...

2013

Broadcasting Private Messages Securely

Suhas Diggavi, Christina Fragouli, László Czap, Vinod Malathidevi Prabhakaran

Consider a source, Alice, broadcasting private messages to multiple receivers through a broadcast erasure channel; users send back to Alice public feedback that she causally uses to decide the coding strategy for her following transmissions. Recently, the ...

IEEE2012

Secure key exchange in wireless networks

Christina Fragouli, László Czap

We investigate the problem of exchanging a se- cret key within a group of wireless devices. In particular, we are interested in information theoretically secure key exchange schemes that enable honest nodes of a multi-hop network to establish a secret grou ...

2011

Secret message capacity of erasure broadcast channels with feedback

Suhas Diggavi, Christina Fragouli, László Czap, Vinod Malathidevi Prabhakaran

We characterize the secret message capacity of a wiretapped erasure channel where causal channel state informa- tion of the honest nodes is publicly available. In doing so, we establish an intimate connection between message secrecy and secret key generati ...

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