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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We evaluate two decades of proposals to replace text passwords for general-purpose user authentication on the web using a broad set of twenty-five usability, deployability and security benefits that an ideal scheme might provide. The scope of proposals we survey is also extensive, including password management software, federated login protocols, graphical password schemes, cognitive authentication schemes, one-time passwords, hardware tokens, phone-aided schemes and biometrics. Our comprehensive approach leads to key insights about the difficulty of replacing passwords. Not only does no known scheme come close to providing all desired benefits: none even retains the full set of benefits that legacy passwords already provide. In particular, there is a wide range from schemes offering minor security benefits beyond legacy passwords, to those offering significant security benefits in return for being more costly to deploy or more difficult to use. We conclude that many academic proposals have failed to gain traction because researchers rarely consider a sufficiently wide range of real-world constraints. Beyond our analysis of current schemes, our framework provides an evaluation methodology and benchmark for future web authentication proposals. 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. Text password is the most popular form of user authentication on websites due to its convenience and simplicity. However, users' passwords are prone to be stolen and compromised under different threats and vulnerabilities. Firstly, users often select weak passwords and reuse the same passwords across different websites. Routinely reusing passwords causes a domino effect; when an adversary compromises one password, she will exploit it to gain access to more websites. Second, typing passwords into untrusted computers suffers password thief threat. An adversary can launch several password stealing attacks to snatch passwords, such as phishing, keyloggers and malware. In this paper, we design a user authentication protocol named oPass which leverages a user's cellphone and short message service to thwart password stealing and password reuse attacks. oPass only requires each participating website possesses a unique phone number, and involves a telecommunication service provider in registration and recovery phases. Through oPass, users only need to remember a long-term password for login on all websites. After evaluating the oPass prototype, we believe oPass is efficient and affordable compared with the conventional web authentication mechanisms. In previous work we presented Pico, an authentication system designed to be both more usable and more secure than passwords. One unsolved problem was that Pico, in its quest to explore the whole solution space without being bound by compatibility shackles, requires changes at both the prover and the verifier, which makes it hard to convince anyone to adopt it: users won’t buy an authentication gadget that doesn’t let them log into anything and service providers won’t support a system that no users are equipped to log in with. In this paper we present three measures to break this vicious circle, starting with the “Pico Lens” browser add-on that rewrites websites on the fly so that they appear Pico-enabled. Our add-on offers the user most (though not all) of the usability and security benefits of Pico, thus fostering adoption from users even before service providers are on board. This will enable Pico to build up a user base. We also developed a server-side Wordpress plugin which can serve both as a reference example and as a useful enabler in its own right (as Wordpress is one of the leading content management platforms on the web). Finally, we developed a software version of the Pico client running on a smartphone, the Pico App, so that people can try out Pico (at the price of slightly reduced security) without having to acquire and carry another gadget. Having broken the vicious circle we’ll be in a stronger position to persuade providers to offer support for Pico in parallel with passwords.