RF fingerprinting exploits the variations in the RF chain of radios to uniquely identify transmitters, and distinguish adversarial transmissions from legitimate nodes. We provide a systematic approach rooted from information theory to understand basic performance limits of RF fingerprinting. We develop a novel channel model to cover RF fingerprinting systems, where the imperfections in the RF chain are modeled as a fingerprint channel, cascaded to the physical channel. We analyze authentication problem in the presence of an adversary, where both the legitimate transmitter and the adversary are equipped with unique fingerprint channels. We provide bounds for the error exponents of the legitimate nodes, and the success exponent of the adversary, as a function of their fingerprints. We illustrate that concepts analogous to Maurer's simulatability are necessary to guarantee authentication via RF fingerprints.
RF fingerprinting exploits the variations in the RF chain of radios to uniquely identify transmitters, and distinguish adversarial transmissions from legitimate nodes. We provide a systematic approach rooted from information theory to understand basic performance limits of RF fingerprinting. We develop a novel channel model to cover RF fingerprinting systems, where the imperfections in the RF chain are modeled as a fingerprint channel, cascaded to the physical channel. We analyze authentication problem in the presence of an adversary, where both the legitimate transmitter and the adversary are equipped with unique fingerprint channels. We provide bounds for the error exponents of the legitimate nodes, and the success exponent of the adversary, as a function of their fingerprints. We illustrate that concepts analogous to Maurer's simulatability are necessary to guarantee authentication via RF fingerprints.
RF fingerprinting exploits the variations in the RF chain of radios to uniquely identify transmitters, and distinguish adversarial transmissions from the transmissions of legitimate nodes. We provide a systematic approach rooted from the information theory to evaluate the basic performance limits of RF fingerprinting. We develop a novel channel model for RF fingerprinting, where the imperfections in the RF chain are modeled as a fingerprint channel, cascaded to the actual physical channel. We address the authentication problem in the presence of an adversary, where both the legitimate transmitter and the adversary are equipped with unique fingerprint channels, in addition to a possible secret key available at the legitimate nodes. We provide bounds for the error exponents for reliable communication of the legitimate nodes, and the success exponent for impersonation and substitution attacks of the adversary, as a function of certain parameters based on their RF-fingerprints, and the shared key rate. We illustrate that keyless authentication is possible via RF fingerprints when the legitimate channel is not simulatable. We also show that the probability of these attacks can be reduced significantly by employing additional dedicated authenticated nodes.
RF fingerprinting exploits the variations in the RF chain of radios to uniquely identify transmitters, and distinguish adversarial transmissions from transmissions of legitimate nodes. We provide a systematic approach rooted from information theory to evaluate basic performance limits of RF fingerprinting. We develop a novel channel model for RF fingerprinting, where the imperfections in the RF chain are modeled as a fingerprint channel, cascaded to the actual physical channel. We address the authentication problem in the presence of an adversary, where both the legitimate transmitter and the adversary are equipped with unique fingerprint channels, in addition to a possible secret key available at the legitimate nodes. We provide achievable bounds for the error exponents for reliable communication of the legitimate nodes, and the success exponent for impersonation and substitution attacks of the adversary, as a function of certain parameters based on their RF-fingerprints, and the shared key rate. We illustrate that keyless authentication is possible via RF fingerprints when the legitimate channel is not simulatable.
The rapid growth in wireless communication systems has provided a flexibility of communication and content that has had a transformative impact to all aspects of society.However, the broadcast nature of the wireless medium makes these systems vulnerable to passive attacks in which the adversary attempts to eavesdrop on the transmitted messages, and to active attacks in which the adversary can intelligently manipulate legitimate transmissions, both of which can jeopardize a myriad of critical wireless services.Hence, it is imperative to design wireless networks with safeguards in place to ensure their resilience to attacks.To that end, this dissertation provides various perspectives in the domain of information theoretic secrecy and authentication, which provably guarantees security, regardless of the computational capabilities of the adversary.We strive to bridge the gap between the information theory of security and the practically implementable protocols within this paradigm.We first consider point to point secure communication over flat fading wireless channels under delay constraint.We extend the definition of outage capacity to account for the secrecy constraint and obtain sharp characterizations of the corresponding fundamental limits under different assumptions on the transmitter channel state information (CSI).The capacity achieving scheme relies on opportunistically exchanging private keys between the legitimate nodes.These keys are stored in a key buffer and used to secure delay sensitive data.We also characterize the optimal 4.5 Multiple Preauthenticated Helpers . . . . . . . . . . . . . . . . . . .
Radio Frequency Identification (RFID) systems represent a key technology for ubiquitous computing and for the deployment of the Internet of Things (IoT). In RFID technology, authentication protocols are often necessary in order to confirm the identity of the parties involved (i.e. RFID readers, RFID tags and/or database servers). In this article, we analyze the security of a mutual authentication protocol proposed by Wang and Ma. Our security analysis clearly shows major security pitfalls in this protocol. Firstly, we show two approaches that an adversary may use to mislead an honest reader into thinking that it is communicating with a legitimate database. Secondly, we show how an adversary that has compromised some tags can impersonate an RFID reader to a legitimate database. Furthermore, we present a new adversary model, which pays heed on cases missed by previous proposals. In contrast to previous models where the communication between an RFID reader and a back-end server is through a secure channel, our model facilitates the security analysis of more general schemes where this communication channel (RFID reader-to-server) is insecure. This model determines whether the compromise of RFID tags has any impact on the security of the reader-to-server communication or vice versa. In a secure protocol, the possible compromise of RFID tags should not affect the RFID reader-server communication. In this paper, we show that compromising of RFID tags in Wang and Ma protocol has a direct impact on the reader-server security. Finally, we propose a new authentication protocol that offers an adequate security level and is resistant against the mentioned security risks. The security proofs of the proposed protocol are supported with Gong-Needham-Yahalom (GNY) logic and Scyther tool, which are formal methods to evaluate the security of a cryptographic protocol.
We consider the problem of keyless message authentication over noisy channels in the presence of an active adversary. Different from the existing models, in our model, the legitimate users do not have any pre-shared key for authentication. Instead, we use the noisy channel connecting the legitimate users for authentication. The main idea is to utilize the noisy channel connecting the legitimate users to distinguish a legitimate message from a fake message, by generating an output at the receiver that is difficult for the adversary to replicate through its noisy channel. By interpreting the message authentication as a hypothesis testing problem, we investigate the authentication exponent and the authenticated channel capacity of the noisy channel. In the authentication exponent problem, for a given message rate, we investigate the speed at which the optimal successful attack probability can be driven to zero. We fully characterize the authentication exponent for the zero-rate message case and provide both an upper bound and a lower bound on the exponent for the non-zero message rate case. In the authenticated capacity problem, we study the largest data transmission rate under which the attacker's optimal successful attack probability can still be made arbitrarily small. We establish an all or nothing result. In particular, we show that the authenticated channel capacity is the same as the classic channel capacity if a simulatability condition is not satisfied, while the authenticated capacity will be zero if this condition is satisfied. We also provide efficient algorithms to check this condition. We further show that our results are robust to modeling uncertainties about the eavesdropper's channels.
This dissertation studies how information-theoretically secure mechanisms for confidentiality and data-traffic privacy can be incorporated into existing and emerging wireless systems. The dissertation consists of three parts. In the first two parts, we study how certain properties of wireless channels can be employed to enhance confidentiality services that have traditionally been the responsibility of higher layers. We first explore the use of the wireless medium for the extraction of secret keys at the two ends of a wireless link, wherein the transceivers at either end are separated by a rich multipath scattering environment. We build a low complexity algorithm that allows two wireless devices to extract a common sequence of random secret bits, by repeatedly probing and estimating a time-varying channel between themselves. Further, we report on an implementation and evaluation of our algorithm on a modified 802.11a system. Next, we study the problem of securely pairing wireless devices in proximity of one another by establishing a shared secret key using a public source of RF transmissions. We employ measurement data to characterize the rate at which bits can be extracted and explore the simultaneous use of multiple transmitters to increase rate. Finally, we study the case when the public transmitter itself is under the arbitrary control of an adversary and we demonstrate a method that can allow successful key-extraction even with such an active adversary. In the final part of this dissertation, we introduce the problem of an unintended information-leakage channel in data traffic consisting of varying packet sizes. Packet sizes convey semantic information that can be related to their con- tent, which can be used as a fingerprint for classification. We formally study the packet-size side channel and explore obfuscation approaches to prevent infor- mation leakage, while considering padded dummy traffic and delay as bounded resources. We show that randomized algorithms for obfuscation can be studied as well known information-theoretic constructs, such as discrete channels with and without memory, and often lead to efficiently solvable constrained optimization problems.