Think this through Kocherrlakota

Narayana Kocherlakota: The right answer is to abolish currency and move completely to electronic cash, an idea suggested at various times by Marvin Goodfriend of Carnegie-Mellon University, Miles Kimball of the University of Colorado and Andrew Haldane of the Bank of England. Because electronic cash can have any yield, interest rates would be able go as far into negative territory as the market required.

Mr. K and his references are still a bit confused about digital cash.  The reason Mr. K gets the properties he wants is regulation, he assumes a government regulation that all cash transaction must clear at a depository institution.    The regulation is unenforceable.   If folks ignore the regulation, then there transactions are peer to peer, and the deposit at the bank is pending indefinitely.  Even then , the cash may go through multiple transactions before being deposited.  In other words, when we ignore the silly government rule we get pure, digital cash and it has all the same properties as paper currency, we can hold secure digits in out wallet.

He compounds his contradiction:

Second, currency does provide a service beyond being a store of value and a medium of exchange: It's anonymous and thus ensures the privacy of transactions. In its absence, governments would have to allow the private sector to offer alternatives with the same attractive features.

Private actors are going to use digital cash technology, outside ot the central bank depository regime.  Hence, Mr. K has defined pure, digital cash, which can securely account and hold digits using a distributed clearing function.