3 research outputs found
Security Analysis of a Proxy Signature Scheme over Braid Groups
Delegation of powers is a common practice in the
real world. To realized the delegation of powers electronically,
Mambo,Usuda and Okamoto proposed the
first proxy signature scheme in 1996. Since then a
number of new schemes and their improvements have
been proposed. In 2008, Verma proposed a proxy signature
scheme over braid groups. This paper analyzes
Vermas scheme and found that this scheme suffers
with the serious security flaws. In this scheme,the
proxy signer is able to misuse his delegated signing
capabilities and the original signer can not restrict the
proxy signer for misuse her delegation power. As a result,
the proposed scheme does not satisfy some essential
security requirements. Vermas proposed scheme
is also not secure against the original signer and proxy
singer changing attacks. Thus, the proposed scheme
is not only insecure against the attacks by original
signer and proxy signer but also has pitfalls against
the forgery attacks mounted by any antagonist
improved privacy-protecting proxy signature scheme
The proxy signature allows a proxy signer to sign on behalf of an original signer and can be verified by anyone with access to the original signers public key. Recently, Dai et al. proposed a privacy-protecting proxy signature scheme. In thi