The United States Constitution, Article I, Section 8 reads in part,
The Congress shall have Power To coin Money, regulate the Value thereof, and of foreign Coin.
From this passage, I understand that only Congress has the power to create and regulate currency (a means of payment and a store of value) in the United States. Congress may also delegate some or all parts of this power, which they have done in favor of the Federal Reserve. By that understanding, any instrument used as a means of payment and a store of value not produced by Congress or under Congressional mandate violates Article I, Section 8 of the Constitution. A recent example of such a violation is the Liberty Dollar, a privately minted coinage distributed and redeemable within the United States and backed by precious metals.
Given that Congress has been explicitly given the power to coin and regulate the value of money in the United States, how are cryptocurrencies, such as Bitcoin, Ethereum, and Basis created, distributed, and redeemed such that they have not been found unconstitutional?
As a slight tangent, what laws allow for the creation and distribution of cryptocurrencies?