@TechReport{Dartmouth:TR2009-643,
  author = {Man Ho Au and Patrick P. Tsang and Willy Susilo and Yi Mu},
  title = {{Dynamic Universal Accumulators for DDH Groups and Their Application to Attribute-Based Anonymous Credential Systems}},
  institution = {Dartmouth College, Computer Science},
  address = {Hanover, NH},
  number = {TR2009-643},
  year = {2009},
  month = {April},
  URL = {http://www.cs.dartmouth.edu/reports/TR2009-643.pdf},
  comment = {
    This report is the extended version of the paper to appear in CT-RSA '09 under the same title.
  },
  abstract = {
    We present the first dynamic universal accumulator that allows (1) the
    accumulation of elements in a DDH-hard group G and (2) one who
    knows x such that y=g^x has --- or has not --- been
    accumulated, where g generates G, to efficiently prove her
    knowledge of such x in zero knowledge, and hence without revealing,
    e.g., x or y.
      We introduce the Attribute-Based Anonymous Credential
    System (ABACS), which allows the verifier to authenticate anonymous
    users according to any access control policy expressible as a
    formula of possibly negated boolean user attributes. We
    construct the system from our accumulator.
  }
}