**Author:**
Philippe Camacho,
A.H.,
Marcos Kiwi, and
Roberto Opazo.

**Abstract:**

Accumulator schemes were introduced in order to
represent a large set of values as one short value called the
*accumulator*.
These schemes allow one to generate membership proofs,
i.e. short witnesses that a certain value belongs to the set.
In universal accumulator schemes, efficient proofs of non-membership
can also be created.
Li, Li and Xue (2007),
building on the work of Camenisch and Lysyanskaya (2002),
proposed an efficient accumulator
scheme which relies on a trusted accumulator manager.
Specifically, a manager that correctly performs accumulator
updates.
In this work we introduce the notion of *strong universal
accumulator schemes* which are similar in functionality
to universal accumulator schemes, but do not assume
the accumulator manager is trusted.
We also formalize the security requirements for such schemes.
We then give a simple construction of a strong universal
accumulator scheme which is provably secure under the
assumption that collision-resistant hash functions exist.
The weaker requirement on the accumulator manager comes
at a price; our scheme is less efficient than known universal
accumulator schemes -
the size of (non)membership witnesses is logarithmic in
the size of the accumulated set in contrast to constant in the
scheme of Camenisch and Lysyanskaya.
Finally, we show how to use strong universal accumulators to
solve a practical concern, the so called e-Invoice Factoring Problem.

**Ref:** In Proceedings of the 11th Information Security Conference (ISC 2008),
Taipei, Taiwan, Sept. 15-18, 2008,
Lecture Notes in Computer Science XXX, pages Y-Z, Springer-Verlag, 2008.

**Full paper:**
Not yet available.