MOST people still think of bitcoin as the virtual currency used by drug dealers and shadowy hackers looking to evade the authorities.
But the innovations that helped turn bitcoin into the most popular virtual currency are now being viewed as a potentially enormous disruptive force for several industries, including accounting, music and law.
Nowhere, though, are more money and resources being spent on the technology than on Wall Street - the very industry that bitcoin was created to circumvent.
"There is so much pull and interest on this right now," said Derek White, chief digital officer at Barclays, the British global bank, which has a team of employees working on about 20 experiments that explore how the technology underlying bitcoin might change finance. "That comes from a recognition that, 'Wow, we can use this to change the fundamental model of how we operate to create our future'."
For people such as Mr White, bitcoin isn't just a digital token to use for online purchases. Instead, many of the top minds in finance have come to believe the software that brought the virtual currency into existence also enables a fundamentally new way of transacting and maintaining records online - allowing people and banks to directly exchange money and assets such as stocks and bonds without having to rely on a long chain of expensive middlemen.
A few banks have gone public with their work, but most of the activity has been happening behind the scenes. At one private meeting, held in April at one of the Manhattan offices of Bank of America, executives from more than a dozen large banks gathered to confidentially discuss how the technology underlying bitcoin could be used to change foreign currency trading, the largest financial market in the world, according to people who attended the meeting.
Central banks such as the Federal Reserve and the Bank of England have their own teams looking at the technology.
"A year ago, it was more of an idea," said Max Neukirchen, head of corporate strategy at JPMorgan Chase. "Now, it is a real opportunity. You test it and realise that this can play a big role in our thinking about how our own infrastructure will evolve."
This is a long way from the derision that many bankers - including JPMorgan chief executive Jamie Dimon - expressed when bitcoin burst into the public consciousness in 2013, when the price of a bitcoin was bouncing around wildly in a speculative frenzy often compared to the Dutch tulip bulb mania.
At the time, some large companies such as Dell and Overstock announced they would start taking bitcoins for online purchases, but few consumers showed much interest in using the digital money to pay their bills, and the furore around bitcoin largely died down.
The institutions that are now becoming involved are generally not interested in selling goods for bitcoins or owning the virtual currency. They are, instead, looking at the network and software that make it possible for bitcoin to move around the world instantly, and almost free.
Until now, digital transactions have always gone through some sort of central authority that can move the money and update the records on both sides - as PayPal and Visa do for many online purchases.
The bitcoin network, on the other hand, is run by a decentralised network of users who jointly keep track of transactions and update the records in real time, with no single user or company in charge. The records of all transactions are kept on a public ledger - essentially just a big, publicly available spreadsheet - known as the blockchain that is visible to anyone and has, at least so far, proven impossible to tamper with.
Much of the work being done inside banks, and in other industries, is looking at whether the blockchain technology can be used independently of the bitcoin virtual currency, which was the first thing to be recorded on the blockchain ledger.
The music publication Billboard recently wrote about how several startups are aiming to use a digital ledger such as the blockchain to keep track of musical downloads and distribute the royalties to artists without relying on a central record keeper.
Vermont's state government commissioned a study in June to look at how a blockchain could be used as a legal method of record keeping under state law; it is one of several governments, many of them outside the United States, looking at the technology.
But the most intense work is being done by financial companies such as the Nasdaq OMX Group, which has several programmers in Manhattan preparing software that the company plans to roll out this year.
The Nasdaq software will allow the trading of stocks in private companies, such as tech startups, on a new kind of blockchain. This will replace the existing system in which private companies issue and trade shares using paper certificates - a process that means even basic trades can take weeks to complete.
Beyond the immediate trial, Nasdaq is experimenting with several other markets in which blockchain-like ledgers could be used to make trading faster and cheaper. The work is being overseen by Fredrik Voss, who recently shifted from his work in the company's commodity division to become its top blockchain executive.
"We believe that blockchain technology holds great promise in allowing capital markets to operate more efficiently while simultaneously providing greater transparency and security, all of which are fundamental to the public interest," Nasdaq chief executive Robert Greifeld said in a July call with investors.
Aside from Nasdaq's project, there is much debate about where the technology is likely to gain its first real world use. At Barclays, some of the 20 internal experiments - most of them conducted at two Barclays offices in London dedicated to the technology - are looking at ways to use the blockchain to speed up and lower the cost of consumer payments, to compete with credit cards and direct money transfers.
But bankers generally say most of the work is aimed at changing the systems that big Wall Street traders and investors use to buy and sell sophisticated assets such as syndicated loans and corporate bonds.
Because any innovation in this area would require the cooperation of multiple banks, the banks have had joint meetings to discuss how they could work together, often led by outside startups looking to provide the software.
One of the most advanced of those conversations has been coordinated by a startup known as R3Cev that is led by a former Wall Street executive, David Rutter. R3Cev has put together models for how banks could trade foreign currencies on a communally maintained spreadsheet such as the blockchain, according to people briefed on the project. It was R3Cev that convened the April meeting at Bank of America, which was attended by more than 75 people from 15 financial institutions, these people said.
This can seem like rather esoteric business, but these are the markets where huge amounts of money turn over each day, and these markets influence the profits of the largest financial institutions. For instance, more than US$3 trillion changes hands each day on the foreign currency market.
For many bankers, the question is not if the technology is put to use, but when. Mr Neukirchen, at JPMorgan, is one of many bankers who expect it will take a few years for the first significant use of blockchain technology to gain traction. White, at Barclays, expects it even sooner, in the next year. NYT