International Association for Cryptologic Research

International Association
for Cryptologic Research

IACR News item: 13 April 2012

Foteini Baldimtsi, Anna Lysyanskaya
ePrint Report ePrint Report
Blind signatures have proved an essential building block for applications that protect privacy while

ensuring unforgeability, i.e., electronic cash and electronic voting. One of the oldest, and most ecient blind

signature schemes is the one due to Schnorr that is based on his famous identication scheme. Although it

was proposed over twenty years ago, its unforgeability remains an open problem, even in the random-oracle

model. In this paper, we show that current techniques for proving security in the random oracle model do not

work for the Schnorr blind signature. Our results generalize to other important blind signatures, such as the

one due to Brands. Brands\' blind signature is at the heart of Microsoft\'s newly implemented UProve system,

which makes this work relevant to cryptographic practice as well.

Expand

Additional news items may be found on the IACR news page.