Private Handshakes

Private handshaking allows pairs of users to determine which (secret) groups they are both a member of. Group membership is kept secret to everybody else. Private handshaking is a more private form of secret handshaking, because it does not allow the group administrator to trace users. We extend the original definition of a handshaking protocol to allow and test for membership of multiple groups simultaneously. We present simple and efficient protocols for both the single group and multiple group membership case. Private handshaking is a useful tool for mutual authentication, demanded by many pervasive applications (including RFID) for privacy. Our implementations are efficient enough to support such usually resource constrained scenarios

Taxes on severance pay, corporate governance and golden handshakes

This paper puts forward an explanation of the rapid increase in golden handshake provision in Europe over the last ten years, based on both enhanced investor protection and attractive tax codes for severance pay. This article takes up a framework in which asymmetric information about the quality of the match between CEO and firm explains the use of golden handshakes for CEOs. It shows how corporate governance and taxation can modify the magnitude and the use of golden handshakes and thus CEO turnover rates. The second-best optimal taxation rate depends on the kind of private benefits accorded to the CEO. I show that golden handshakes should be taxed in the same way as CEO incomes. However, nonpecuniary private benefits strengten the agency cost and require some transfers for firms providing parachute-type contracts. In effect, this means partial exemption. An improvement in the quality of corporate governance should lead to smaller golden handshakes, higher turnover-performance sensitivity and the disappearance of advantageous tax codes for termination pay.CEOs turnover ; corporate governance ; golden handshakes ; optimal taxation ; severance pay.

Securing Cyber-Physical Social Interactions on Wrist-worn Devices

Since ancient Greece, handshaking has been commonly practiced between two people as a friendly gesture to express trust and respect, or form a mutual agreement. In this article, we show that such physical contact can be used to bootstrap secure cyber contact between the smart devices worn by users. The key observation is that during handshaking, although belonged to two different users, the two hands involved in the shaking events are often rigidly connected, and therefore exhibit very similar motion patterns. We propose a novel key generation system, which harvests motion data during user handshaking from the wrist-worn smart devices such as smartwatches or fitness bands, and exploits the matching motion patterns to generate symmetric keys on both parties. The generated keys can be then used to establish a secure communication channel for exchanging data between devices. This provides a much more natural and user-friendly alternative for many applications, e.g., exchanging/sharing contact details, friending on social networks, or even making payments, since it doesn’t involve extra bespoke hardware, nor require the users to perform pre-defined gestures. We implement the proposed key generation system on off-the-shelf smartwatches, and extensive evaluation shows that it can reliably generate 128-bit symmetric keys just after around 1s of handshaking (with success rate >99%), and is resilient to different types of attacks including impersonate mimicking attacks, impersonate passive attacks, or eavesdropping attacks. Specifically, for real-time impersonate mimicking attacks, in our experiments, the Equal Error Rate (EER) is only 1.6% on average. We also show that the proposed key generation system can be extremely lightweight and is able to run in-situ on the resource-constrained smartwatches without incurring excessive resource consumption

DSTC: DNS-based Strict TLS Configurations

Most TLS clients such as modern web browsers enforce coarse-grained TLS security configurations. They support legacy versions of the protocol that have known design weaknesses, and weak ciphersuites that provide fewer security guarantees (e.g. non Forward-Secrecy), mainly to provide backward compatibility. This opens doors to downgrade attacks, as is the case of the POODLE attack [18], which exploits the client's silent fallback to downgrade the protocol version to exploit the legacy version's flaws. To achieve a better balance between security and backward compatibility, we propose a DNS-based mechanism that enables TLS servers to advertise their support for the latest version of the protocol and strong ciphersuites (that provide Forward-Secrecy and Authenticated-Encryption simultaneously). This enables clients to consider prior knowledge about the servers' TLS configurations to enforce a fine-grained TLS configurations policy. That is, the client enforces strict TLS configurations for connections going to the advertising servers, while enforcing default configurations for the rest of the connections. We implement and evaluate the proposed mechanism and show that it is feasible, and incurs minimal overhead. Furthermore, we conduct a TLS scan for the top 10,000 most visited websites globally, and show that most of the websites can benefit from our mechanism

Determinants of Successful Cooperation in a Face-to-Face Social Dilemma

What makes you a successful cooperator? Using data from the British television game show "Golden Balls" we analyze a prisoner's dilemma game and its pre-play. We find that players strategically select their partner for the PD, e.g., they bear in mind whether contestants lied. Players' expectations about the stake size strongly influence the outcome of the PD: The lower the stakes, the more likely players successfully cooperate. Most interestingly, unilateral cooperation is encouraged by mutually promising not to defect and shaking hands on it, but a mere handshake serves as manipulating device and increases successful defection.prisoner's dilemma, cooperative behavior, communication, promises, voting

Compromising Tor Anonymity Exploiting P2P Information Leakage

Privacy of users in P2P networks goes far beyond their current usage and is a fundamental requirement to the adoption of P2P protocols for legal usage. In a climate of cold war between these users and anti-piracy groups, more and more users are moving to anonymizing networks in an attempt to hide their identity. However, when not designed to protect users information, a P2P protocol would leak information that may compromise the identity of its users. In this paper, we first present three attacks targeting BitTorrent users on top of Tor that reveal their real IP addresses. In a second step, we analyze the Tor usage by BitTorrent users and compare it to its usage outside of Tor. Finally, we depict the risks induced by this de-anonymization and show that users' privacy violation goes beyond BitTorrent traffic and contaminates other protocols such as HTTP