Hidden Credential Retrieval, Revisited

SeongHan SHIN  Kazukuni KOBARA  

Publication
IEICE TRANSACTIONS on Fundamentals of Electronics, Communications and Computer Sciences   Vol.E98-A   No.1   pp.428-433
Publication Date: 2015/01/01
Online ISSN: 1745-1337
DOI: 10.1587/transfun.E98.A.428
Type of Manuscript: LETTER
Category: Cryptography and Information Security
Keyword: 
credentials management,  passwords,  on-line/off-line dictionary attacks,  insider/outsider attacks,  

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Summary: 
Hidden Credential Retrieval (HCR) protocols are designed for access credentials management where users who remember short passwords can retrieve his/her various credentials (access keys and tokens) with the help of a remote storage server over insecure networks (e.g., the Internet). In this paper, we revisit two HCR protocols, both of which are based on blind signature schemes: one (we call it B-HCR) was proposed in ASIACCS 2009 and the other (we call it MRS-HCR) was in WISA 2010. In particular, we show that the B-HCR protocol is insecure against an outside attacker who impersonates server S. Specifically, the attacker can find out the user's password pw with off-line dictionary attacks by eavesdropping the communications between the user and a third-party online service provider. Also, we show that the MRS-HCR protocol does not work correctly itself. In other words, user U can not retrieve the plaintext Msg (i.e., credentials) even if he/she has a knowledge of the password.