How to Preserve User Anonymity in Password-Based Anonymous Authentication Scheme

SeongHan SHIN  Kazukuni KOBARA  

Publication
IEICE TRANSACTIONS on Information and Systems   Vol.E101-D   No.3   pp.803-807
Publication Date: 2018/03/01
Online ISSN: 1745-1361
DOI: 10.1587/transinf.2017EDL8183
Type of Manuscript: LETTER
Category: Information Network
Keyword: 
password,  authentication,  user anonymity,  

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Summary: 
A purpose of password-based anonymous authentication schemes is to provide not only password-based authentication but also user anonymity. In [19], Yang et al., proposed a password-based anonymous authentication scheme (we call it YZWB10 scheme) using the password-protected credentials. In this paper, we discuss user anonymity of the YZWB10 scheme [19] against a third-party attacker, who is much weaker than a malicious server. First, we show that a third-party attacker in the YZWB10 scheme can specify which user actually sent the login request to the server. This attack also indicates that the attacker can link different login requests to be sent later by the same user. Second, we give an effective countermeasure to this attack which does not require any security for storing users' password-protected credentials.