dr. prasad: right now, this is not a clear proposal. we have different ways of thinking about the digital currency. the notion of deposit account is of non-interest-bearing deposit accounts. you can have these assets superseding other assets -- that is unlikely. immigrant your concern about potential ecological malfeasance, this is when paper currency when counterfeiting was a concern. one could argue that digital forms of fiat currency could reduce paper currency, there on the flipside. in most issues, there is one side and the other side. the flipside is that they would make them very vulnerable to technological hacks. this is why i think most central banks are very concerned about moving forward aggressively with this. >> the promise of block chain is non-supply will ledger that would prevent a lot of malfeasance. i think the kind that you will forever be worried about is a business of authenticating a person who is access to move these bounces around. that remains an unsolved problem in the digital world. how you really authenticate

dr. prasad? >> it is difficult to see an asset that has no intrinsic value and no backing by the government maintaining value. the initial promise of something like bitcoin might become an effective medium of exchange and that promise hasn't quite panned out because it is very inefficient and very costly to transact using bitcoin. in fact, many of the nonofficial crypto currencies gaining traction, in fact, once they are backed by fiat currencies or other forms of banking. there is one called tether, for instance, backed 1 for 1 with the u.s. dollar and that is beginning to get traction as a medium of exchange. ultimately, the u.s. dollar, as just pointed out, maintaining its dominant role to u.s. institutions and the trust in the federal reserve. >> let me follow up by basically -- by starting with a more fundamental question. you talked about the volatility of digital currency. and maybe that is the principle reason why it's not the best exchange right now. at its very core, are crypto currenci