Joshua Lampkins

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Most current digital currency schemes and associated ledgers are either centralized or completely distributed similar to the design adopted by Bitcoin. Centralized schemes enable accountability, but leave the privacy of users' identities and transactions in the hands of one organization. Distributed schemes can ensure better privacy but provide little(More)
Proactive secret sharing (PSS) schemes are designed for settings where long-term confidentiality of secrets has to be guaranteed, specifically, when all participating parties may eventually be corrupted. PSS schemes periodically refresh secrets and reset corrupted parties to an uncorrupted state; in PSS the corruption threshold t is replaced with a(More)
In PODC 1991 Ostrovsky and Yung [35] introduced the proactive security model, where corruptions spread throughout the network, analogous to the spread of a virus or a worm. PODC 2006 distinguished lecture by Danny Dolev, that also appears in the PODC06 proceedings, lists the above work as one of PODC's "Century Papers at the First Quarter-Century Milestone"(More)
In a secret sharing scheme a dealer shares a secret <i>s</i> among <i>n</i> parties such that an adversary corrupting up to <i>t</i> parties does not learn <i>s</i>, while any <i>t</i>+1 parties can efficiently recover <i>s</i>. Over a long period of time all parties may be corrupted thus violating the threshold, which is accounted for in <i>Proactive(More)
In this paper we argue that privacy-preserving digital coins with low computation and communication overhead can be utilized as micropayments to harden online applications and services. We call such digital coins App Coins, and the applications that use them App Coins-hardened applications. Our thesis is that App Coins-hardened applications can greatly(More)
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