  In an open network environment, privacy of group communication and integrity
of the communication data are the two major issues related to secured
information exchange. The required level of security may be achieved by
authenticating a group key in the communication channel, where contribution
from each group member becomes a part of the overall group key. In the current
work, we have developed an authentication system through Central Administrative
Server (CAS) for automatic integration and validation of the group key. For
secured group communication, the CAS generates a secret alphanumeric group key
image. Using secret image sharing scheme, this group key image shares are
distributed among all the participating group members in the open network. Some
or all the secret shares may be merged to reconstruct the group key image at
CAS. A k-nearest neighbor classifier with 48 features to represent the images,
is used to validate the reconstructed image with the one stored in the CAS. 48
topological features are used to represent the reconstructed group key image.
We have achieved 99.1% classification accuracy for 26 printed English uppercase
characters and 10 numeric digits.
