More currency, barter, legal tender info (see http://en.wikipedia.org/wiki/Currency) describes how a Central Bank may have sole control over a nation's CURRENCY (as opposed to foreign currency that are sometimes specifically lawfully excluded as payment substitute for the national currency).  Central Banks generally does not have sole control over COMMODITIES.

Exchange control also has legal implications when dealing in foreign currency (currency other than the national currency) in some jurisdictions (see http://en.wikipedia.org/wiki/Foreign_exchange_controls).

When owning the keys to unlock a mathematical problem, it should constitute a store of value in the form of COMMODITY ownership of instant access to a mathematical sollution to a complicated problem.