Meet Darkcoin - Bitcoin's Shadowy Cousin
Cryptocurrency Darkcoin - known as the shadowy cousin of Bitcoin - is booming.
In just one month, the value of the little-known alternative online currency has soared from 75 cents (45p) to $7 (£4.14).
Its main selling point is its increased anonymity in comparison to Bitcoin - meaning it is very difficult to trace a payment to a person.
Cryptocurrencies like Bitcoin have soared in popularity, and have become notorious as a way to buy drugs, weapons and other illicit items online.
Darkcoin is one of the fastest-growing cryptocurrencies, and the total value of its combined coins is around $30m (£17.8m).
The extra layer of anonymity comes from the way Darkcoin jumbles up the transactions individual users make with those of two other users.
The feature, called Darksend, means discovering where a user's cash has ended up is more difficult.
Bitcoin consultant Kristov Atlas told Wired he believed the price rise was based on the privacy features, and was not just a bubble.
He said: "It's not purely a speculative bubble. There's some solid indications the market price is currently based on the fundamental value of the coin."
Bitcoin trader Allen Price added: "I had sort of smugly stood to the side waiting for the big, inevitable crash with an 'I told you so' ready.
"But no crash ever really came, and it's been kind of an ongoing success for investors."
Like Bitcoin, Darkcoin can be "mined" by anyone who repeatedly carries out a specific computer function using powerful hardware.
The value of the currency is based on trades between creators and owners of the Darkcoin.