IACR News item: 27 February 2015
Kai-Min Chung, Jonathan Katz, Hong-Sheng Zhou
ePrint ReportWe show how to use \\emph{hardware tokens} to overcome these impossibility results. In our envisioned scenario, an authority gives a hardware token and some cryptographic information to each authorized user; the user combines these to decrypt received ciphertexts. Our schemes rely on \\emph{stateless} tokens that are \\emph{identical} for all users. (Requiring a different token for each user trivializes the problem, and would be a barrier to practical deployment.) The tokens can implement relatively ``lightweight\'\' computation relative to the functions supported by the scheme.
Our token-based approach can be extended to support hierarchal functional encryption, function privacy, and more.
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