First page of the summary:

Ultimately, it seems clear that a non-state actor (indeed, even a
state actor) would face significant challenges against a determined hightiered
opponent given the underlying assumptions and implementation
of VCs. As a general matter, a high-tiered opponent would be able
to successfully attack any target of interest in cyberspace if enough
resources were invested. In the case of a VC, which would require trust,
anonymity, and availability of widely deployed cyber services (such as
wallet and mining applications), it seems infeasible that a consistently
successful cyber defense can be mounted. The only hope might be
if the non-state actor were supported by a sophisticated nation-state
opponent who was capable of defending against such threats. Even in
this scenario, it is unclear whether such coordination would work, particularly
in the case of a Tier V and VI opponent.

The Department of Defense should be aware of the following:

[Virtual Currencies]'s represent the latest step toward decentralized cyber services.
In particular, the historical trend suggests the development
of a resilient public cyber key terrain, which this report
defines as the ability of unsophisticated cyber actors to have
persistent, assured access to cyber services regardless of whether
a highly sophisticated state actor opposes their use. This has
implications for national firewalls, access to extremist rhetoric,
the feasibility of nation-state cyber attacks, and the ability to
maintain uninterruptible and anonymous encrypted links.

This report will examine the potential for terrorist, insurgent,
or criminal groups to increase their political and/or economic power
by deploying a VC to use as a currency for regular economic transactions
rather than exploiting existing VCs as a means of illicit transfer,
fundraising, or money laundering.