10 research outputs found
How to Split a Secret into Unknown Shares
Grigoriev and Shpilrain recently considered secret sharing systems for which nobody (including the dealer) knows the share of a particular party and introduced a construction for the special case of all-or-nothing schemes. We extend their work and propose two threshold secret sharing schemes that satisfy this property
Dealer-Leakage Resilient Verifiable Secret Sharing
Verifiable Secret Sharing (VSS) guarantees that honest parties reconstruct a consistent secret even in the presence of a malicious dealer that distributes invalid shares. We empower the dishonest dealer and consider the case when he subliminally leaks information in valid shares, allowing an adversary to access the secret prior to the reconstruction phase. We define the concept of Dealer-Leakage Resilient Verifiable Secret Sharing (DLR-VSS) as a stronger notion of VSS that achieves security under this settings. We propose an efficient DLR-VSS and prove its properties in the semi-honest adversarial model
SETUP in Secret Sharing Schemes using Random Values
Secret sharing schemes divide a secret among multiple participants so that only authorized subsets of parties can reconstruct it. We show that SETUP (Secretly Embedded Trapdoor with Universal Protection) attack can be embedded in secret sharing schemes that employ enough randomness to give the attacker an overwhelming advantage to access the secret. In case of ideal schemes, a coalition of a few participants (within at least one is the attacker) can succeed the attack, while in case of non-ideal schemes the attacker\u27s knowledge can be enough to reveal the secret. We exemplify the attack against Shamir\u27s threshold scheme, which is the most well-known and used secret sharing scheme. Finally, we consider some prevention techniques against the proposed attack
Experimental Analysis of Subscribers' Privacy Exposure by LTE Paging
Over the last years, considerable attention has been given to the privacy of
individuals in wireless environments. Although significantly improved over the
previous generations of mobile networks, LTE still exposes vulnerabilities that
attackers can exploit. This might be the case of paging messages, wake-up
notifications that target specific subscribers, and that are broadcasted in
clear over the radio interface. If they are not properly implemented, paging
messages can expose the identity of subscribers and furthermore provide
information about their location. It is therefore important that mobile network
operators comply with the recommendations and implement the appropriate
mechanisms to mitigate attacks. In this paper, we verify by experiment that
paging messages can be captured and decoded by using minimal technical skills
and publicly available tools. Moreover, we present a general experimental
method to test privacy exposure by LTE paging messages, and we conduct a case
study on three different LTE mobile operators
5G Multi-access Edge Computing: Security, Dependability, and Performance
The main innovation of the Fifth Generation (5G) of mobile networks is the
ability to provide novel services with new and stricter requirements. One of
the technologies that enable the new 5G services is the Multi-access Edge
Computing (MEC). MEC is a system composed of multiple devices with computing
and storage capabilities that are deployed at the edge of the network, i.e.,
close to the end users. MEC reduces latency and enables contextual information
and real-time awareness of the local environment. MEC also allows cloud
offloading and the reduction of traffic congestion. Performance is not the only
requirement that the new 5G services have. New mission-critical applications
also require high security and dependability. These three aspects (security,
dependability, and performance) are rarely addressed together. This survey
fills this gap and presents 5G MEC by addressing all these three aspects.
First, we overview the background knowledge on MEC by referring to the current
standardization efforts. Second, we individually present each aspect by
introducing the related taxonomy (important for the not expert on the aspect),
the state of the art, and the challenges on 5G MEC. Finally, we discuss the
challenges of jointly addressing the three aspects.Comment: 33 pages, 11 figures, 15 tables. This paper is under review at IEEE
Communications Surveys & Tutorials. Copyright IEEE 202
Attacks on cMix - Some Small Overlooked Details
Chaum et al. have very recently introduced cMix as the first practical system that offers senders-recipients unlinkability at scale. cMix is claimed by its authors to be secure unless all nodes collude. We argue their assertion does not hold for the basic description of the protocol and sustain our statement by two different types of attacks: tagging attack and insider attack. For each one, we discuss the settings that make it feasible and possible countermeasures. By this, we highlight the necessity of implementing additional mechanisms that at first have been overlooked or have only been mentioned as additional features
Security of Linear Secret-Sharing Schemes against Mass Surveillance
Following the line of work presented recently by Bellare, Paterson and Rogaway, we formalize and investigate the resistance of linear secret-sharing schemes to mass surveillance. This primitive is widely used to design IT systems in the modern computer world, and often it is implemented by a proprietary code that the provider (“big brother”) could manipulate to covertly violate the privacy of the users (by implementing Algorithm-Substitution Attacks or ASAs). First, we formalize the security notion that expresses the goal of big brother and prove that for any linear secret-sharing scheme there exists an undetectable subversion of it that efficiently allows surveillance. Second, we formalize the security notion that assures that a sharing scheme is secure against ASAs and construct the first sharing scheme that meets this notion. This work could serve as an important building block towards constructing systems secure against mass surveillance
Cryptanalysis of a Password-based Group Key Exchange Protocol Using Secret Sharing
Yuan et al. recently introduced a password-based group key transfer protocol that uses secret sharing, which they claim to be efficient and secure [9]. We remark its resemblance to the construction of Harn and Lin [1], which Nam et al. proved vulnerable to a replay attack [3]. It is straightforward that the same attack can be mount against Yuan et al.’s protocol, proving that the authors’ claim is false. In the same paper, Nam et al. propose a countermeasure that may also apply to Yuan et al.’s protocol. However, we show that their protocol remains susceptible to an insider attack (even if it stands against the replay attack): any malicious participant can recover the long-term secret password of any other user and therefore becomes able to compute group keys he is unauthorized to know