In my earlier post, I have noted why legal ownership of cryptocurrency matters. The use of cryptocurrency as a collateral is also imaginable.
The prerequisites for acquiring such proprietary rights and their effect are to be determined by legal rules. In the absence of internationally uniform rules, an applicable national legal system must be determined by choice-of-law rules of the country in which such issues are litigated or considered.
With respect to a tangible item, proprietary issues are subject to the law of the country where it is situated (lex situs or lex loci rei sitae) under the prevailing choice of law rules. With respect to intangible goods, choice-of-law rules are not as well established. In one of my articles, I have argued that the proprietary issues of an emissions quota, a species of intangible goods, should be subject to the law of the country where it is registered.
Cryptocurrency is intangible. It is also a financially valuable data (information) as is an emissions quota. However, unlike the latter which is registrable on a national registry, cryptocurrency is registered on a blockchain which is borderless. This makes it difficult to localise cryptocurrency in a particular country for choice-of-law purposes.