IACR News item: 01 May 2015
Stephen R. Tate, Roopa Vishwanathan
ePrint Reportsignatures that prove that an authority has issued the signer
``attributes\'\' that satisfy some specified predicate. In existing
attribute-based signature schemes, keys are valid indefinitely once
issued. In this paper, we initiate the study of incorporating time into
attribute-based signatures, where a time instance is embedded in every
signature, and attributes are restricted to producing signatures with
times that fall in designated validity intervals. We provide
three implementations that vary in granularity of assigning validity
intervals to attributes, including a scheme in which each attribute
has its own independent validity interval, a scheme in which all
attributes share a common validity interval, and a scheme in which
sets of attributes share validity intervals. All of our schemes provide anonymity to a signer, hide the attributes used to create the signature, and provide collusion-resistance between
users.
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