We investigated the operational capabilities of blockchain and several other distributed ledger techniques that are being used in cryptocurrencies. Our objective was to characterize the capabilities of the techniques and their limitations as they apply to distributed healthcare and simulation applications. This paper reports on the capabilities that appear to be applicable to distributed training simulation. It also discusses the limitations of these techniques which may impact practical applications.
Blockchains or distributed ledgers lend themselves most readily to services like the distributed network loggers and After Action Review systems that are used in networked simulation events. The logger applications record the stream of messages that have been exchanged between simulators, while AAR applications analyze and replay the data to provide feedback to the participants. In addition to logging messages, a blockchain adds features that are important in currency exchanges, such as partial anonymity, security against forgery, distributed validation, immutability of recorded transactions, and public access to the log. These features require computer resources for hash functions, encryption, and network communication, which can result in slow transactions and limitations on the size of the chain that maintains the ledger.
After investigating multiple distributed ledger techniques, our conclusion is that the core features of blockchain are not useful for replacing existing services in distributed simulation. This conclusion is derived from the fact that blockchain was created to enable the processing of valuable data between participants who do not trust each other, and within a system that was previously highly inefficient and costly because of the convoluted mechanisms needed to prevent fraud. Distributed military simulation systems are composed of nodes that are trusted and which have been configured for performance in the absence of internal network threats. Therefore, the core advantages of blockchain are not applicable in this environment. However, the components of blockchain may provide secure, verifiable identifiers for network participants and indices across multiple legacy data storage services, which may be useful new services for simulation operators and sponsors.