Tools that synchronize passwords over several user devices typically store the encrypted passwords in a central online database. For encryption, a low-entropy, password-based key is used. Such a database may be subject to unauthorized access which can lead to the disclosure of all passwords by an offline brute-force attack. In this paper, we present PALPAS, a secure and user-friendly tool that synchronizes passwords between user devices without storing information about them centrally. The idea of PALPAS is to generate a password from a high entropy secret shared by all devices and a random salt value for each service. Only the salt values are stored on a server but not the secret. The salt enables the user devices to generate the same password but is statistically independent of the password. In order for PALPAS to generate passwords according to different password policies, we also present a mechanism that automatically retrieves and processes the password requirements of services. PALPAS users need to only memorize a single password and the setup of PALPAS on a further device demands only a one-time transfer of few static data.
Approaches which are using hardware tokens @cite_17 @cite_21 or mobile devices @cite_22 for authentication have the disadvantage that users always need to carry an additional device. Furthermore, such solutions require changes on the infrastructure of the service. The weak development of other authentication mechanisms than passwords (cf. @cite_29 for a survey) shows that service-side changes are a major obstacle for the wide adoption of authentication schemes.
@cite_29 @cite_21 @cite_22 @cite_17
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Strong authentication for online service access typically requires some kind of hardware device for generating dynamic access credentials that are often used in combination with static passwords. This practice have the side effect that users fill up their pockets with more and more devices and their heads with more and more passwords. This situation becomes increasinlgy difficult to manage which in turn degrades the usability of online services. In order to cope with this situation users often adopt insecure ad hoc practices that enable them to practically manage their different identities and credentials. This paper explores how one single device can be used for authentication of user to service providers and server to users, as well as provide a range of other security services. User authentication systems are at an impasse. The most ubiquitous method -- the password -- has numerous problems, including susceptibility to unintentional exposure via phishing and cross-site password reuse. Second-factor authentication schemes have the potential to increase security but face usability and deployability challenges. For example, conventional second-factor schemes change the user authentication experience. Furthermore, while more secure than passwords, second-factor schemes still fail to provide sufficient protection against (single-use) phishing attacks. We present PhoneAuth, a system intended to provide security assurances comparable to or greater than that of conventional two-factor authentication systems while offering the same authentication experience as traditional passwords alone. Our work leverages the following key insights. First, a user's personal device (eg a phone) can communicate directly with the user's computer (and hence the remote web server) without any interaction with the user. Second, it is possible to provide a layered approach to security, whereby a web server can enact different policies depending on whether or not the user's personal device is present. We describe and evaluate our server-side, Chromium web browser, and Android phone implementations of PhoneAuth. In terms of convenience requirements, mobility has been one of the most important services for pay-TV systems. In 2009, Yang and Chang proposed an authentication protocol for mobile devices using elliptic curves cryptography (ECC) and claimed that their mechanism is secure and efficient using in mobile pay-TV systems. In this paper, we demonstrate that their protocol still is insecure for authentication without password protection and performs inefficiently. Therefore, we offer an anonymous authentication protocol (AAP) to solve the performance issue and insecure risks. In addition, we present an analysis of our protocol to show that our protocol suits better for applications with higher security requirements and low power-consuming devices. The emergence of powerful, sensor-rich devices has led to the development of continuous authentication (CA) schemes using off-the-shelf hardware, where user behaviour is compared to past experience to produce an authentication decision with the aim of addressing challenges with traditional authentication schemes. Current CA proposals, however, have largely neglected adversaries present in a real-world deployment, namely the ubiquity of mal ware and software attacks. This has particular importance when a device cannot be trusted by a third-party, such as a corporation, that controls access to assets based on that decision. A software compromise, either on the scheme implementation or platform, may enable an adversary to modify authentication scores to alter the status of the device in reality, give insights into user behaviour, or gain unauthorised access to restricted assets. Hence, for the first time, we examine two standardised constructs that offer isolated and trusted execution - Secure Elements (SEs) and Trusted Execution Environments (TEEs) - even when an adversary has root-level privileges, and propose measures for providing trusted CA while retaining deployability. Based on these, we implement the first system for evaluating TEE-based CA on a consumer mobile device using Intel SGX, thus providing confidentiality, integrity and trust while removing the main platform from the TCB. We present an empirical evaluation of TEE-and non-TEE performance using methods proposed in related CA schemes. Our results indicate that trusted CA can be provided with no significant performance penalty, and may even offer performance benefits.