There is your digital fiat

TrustToken, the company behind the TrueUSD stablecoin, has raised $20 million in a strategic funding round from Andreessen Horowitz, BlockTower Capital, Danhua Capital, GGV Capital, and other parties.

This digital dollar needs cooperating banks. They have it for a simple reason, the central banks are opening up their exchange network to fintech. 

This coin likely uses blockchain to track the digital dollars.  I did not check.  But a coin on a block chain is not a cryptocoin, but it uses a crypto wallet.   

Banks can be the first to make a true crypto coin.  First, the banks need to deliver the cash verification key which can be public.  Each processor with this key can verify the digital stream is valid money.  The generator of money needs a secret, private key and only it can generate the 'cash watermarks', (crypto signature). From there is is a matter of verifying that all parties use the secure interpreter and valid exchange bots such that no double spend is possible.  

This is true crypto cash, but we do not even need that if we can limit the number exchange per cash unit to finite, then we can use a small blockchain with trusted miners.  Delete the cash trace from the chin when the transaction count is reached, or the cash is cleared back to the bank.  I call this a liquidity machine as opposed to true crypto coin. Both, I consider, bearer cash.

Under the block chain system we have, here is no digital bearer cash at all, cryoto or otherwise. Everything is referred to block chain, though this is changing very rapidly as the new liquidity tech is deployed in swap nets.