Enabling fair offline trading

ABSTRACT

Offline trading allows users to trade rights associated with digital content or any other digital asset without immediate access to a central authority. To conduct an offline trade all involved parties sign a contract describing the transaction. Later this contract may then be submitted to a central authority (e.g., a digital content repository or a bank) to conduct the actual change of ownership as specified in the contract. In this paper we show that there is a crucial problem when using offline trading: whoever signs the contract first is providing the other parties with an option to unilaterally control the contract. The other parties may sign the contract later and submit it to complete the transaction. Or they may simply discard it. If the value of the involved goods change over time, this option may have a significant value. We introduce an approach to limit the value of options granted through offline contract signing and discuss its impact, design alternatives as well as related aspects.

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INDEX TERMS

Primary Classification:
  K. Computing Milieux
  K.4 COMPUTERS AND SOCIETY

Additional Classification:
  K. Computing Milieux
  K.4 COMPUTERS AND SOCIETY
      K.4.4 Electronic Commerce
  K.8 PERSONAL COMPUTING

General Terms:
Algorithms, Design

Keywords:
digital ownership, fair exchange of signatures, offline trading, simultaneous contract signing