![](bg5.png)
present. We suggest using the scheme described by
Arboit, G. et al., (2008) where the certificate
revocation scheme requires that participants of the
system monitor the behavior of the other nodes.
4 PARTICIPANT
ADDITION-REMOVAL
One of the important benefits of the proposed
certification scheme is its ability to easily add and
remove Participants in the group U. To achieve that,
we adopt the participant addition-deletion
mechanism proposed by Noack and Spitz (2009).
We assume that the certification scheme has been
already established, that every participant has his
local public-private key pair, his partial public key
pair as well as his legitimate certificate and that he
has contributed successfully to the generation of the
global public-private key pair of the distributed CA.
We employ the share renewal technique of
Noack and Spitz (2009), based on the PSS scheme
of Herzberg, A. et al., (1995). PSS updates already
distributed shares of all n members to provide
proactive security. While adding a participant, +1
members of U, forming a subset U
splt
, split off a part
of their secret and share this part with the new
member. Removing a participant is done by
computing and redistributing the participant's secret
to some remaining U members.
4.1 Addition-Removal Certificate
Management
Addition - Removal of Participants has no effect in
the global public key of the distributed certification
scheme. So, certificates remain valid even after the
partial public-private key pairs change values and
can still be issued or verified. This happens due to
the fact that the local public private key pairs that
handle secure communication between participants
are different in principle from the partial public –
private key pairs. Local key pairs are only changing
in a certificate reissuing operation after a participant
addition –removal. In that case, the reissuing
certificate procedure is different than the one
described in 3. In certificate reissuing after
participant addition –removal, the partial key pair
replaces the local key pair of a requesting participant
and subsection 2.2, 2.3 processes are executed.
5 CONCLUSIONS
In this paper, an ECC based fully distributed
Threshold cryptography certification scheme was
proposed that eliminates the need for trusted dealer
for secret sharing. The certification infrastructure is
self-organized and fully decentralized. Also, using
the mechanism described by Noack and Spitz
(2009), addition and removal of participants is
achieved while keeping the global public key
unchanged..
ACKNOWLEDGEMENTS
The reported work is supported through the
SECRICOM FP7 FP7 SEC 218123European project
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