A digital currency without a central bank could be ideal for economies where the mobile phone is king but the banking systems are weak.

Recent months have not been kind to proponents of Bitcoin, the virtual peer-to-peer currency that soared to a value of over $30 last summer on a surge of public interest and media reports.

The currency operates over the Internet with no central control. But now its 15 minutes of fame appear to be over. Reports of a $500,000 digital heist last year were followed by wild volatility in the value of a bitcoin, which has now dropped to around $5. Last month, the largest exchange where bitcoins could be traded for dollars unexpectedly closed because of what it called “increasing regulation.”