The concept of electronic cash or digital currency is not new. Since the 1980s, e-cash protocols have existed that are based on a model proposed by David Chaum.
Just as understanding the concept of distributed systems is necessary to comprehend blockchain technology, the idea of electronic cash is also essential in order to appreciate the first and astonishingly successful application of blockchain, Bitcoin, or more broadly cryptocurrencies in general.
Two fundamental e-cash system issues need to be addressed: accountability and anonymity.
Accountability is required to ensure that cash is spendable only once (double-spend problem) and that it can only be spent by its rightful owner. Double spend problem arises when same money ...
