At present,
the solution to the network path disconnection problem in all DTN data delivery methods is that the physical movement of nodes must be exploited to carry messages around the network.
This solution is referred to as store-carry-and-forward scheme Guo etal.(2010).
The sporadic connectivity of DTN raises a number of security-related challenges due to frequent partitioning and a lack of reliable complete source-to-destination path (Defrawy etal.,2009).
An overview of those challenges is given in Farrell et al.(2009).
One of the challenges is initial secure context establishment since it is unrealistic to assume that public key infrastructure (PKI) is always globally present and available (Defrawy etal.,2009).
Hence,
key management has been recognized as an open problem (Farrell, 2007).