TOKYO (BLOOMBERG) - At 2:57am on Friday morning (Jan 26) in Tokyo, someone hacked into the digital wallet of Japanese cryptocurrency exchange Coincheck and pulled off one of the biggest heists in history.

Three days later, the theft of nearly US$500 million in digital tokens is still reverberating through cryptocurrency markets and policy circles around the world.

The episode, disclosed by Coincheck executives at a hastily arranged press conference on Friday night, comes at an awkward time for Japanese regulators, who began rolling out a new licencing system for cryptocurrency venues just a few months ago. It has heightened calls for stricter oversight and may influence a closely watched debate in neighboring South Korea over whether to ban digital-asset exchanges outright.

While Bitcoin and its ilk have mostly recovered from their selloff on Friday - thanks in part to Coincheck's assurances over the weekend that customers would be reimbursed - market observers say concerns over security lapses at cryptocurrency exchanges are likely to persist. They may even push some investors toward peer-to-peer methods of trading that do not rely on centralised platforms.

"The latest theft will have two immediate effects: more regulation by the authorities over exchanges and more recognition of the advantages offered by decentralised ways of trading," said David Moskowitz, co-founder of Indorse Pte in Singapore, which runs a social network for blockchain enthusiasts.

The Coincheck incident adds to a long list of thefts at cryptocurrency exchanges and wallets, stretching back to the robbery of Tokyo-based Mt. Gox in 2014. A lack of confidence in such platforms has prompted many institutional investors to spurn cryptocurrencies, although some are now dipping into the market after CME Group and Cboe Global Markets introduced regulated Bitcoin futures in the US last month.

Coincheck, one of Japan's biggest cryptocurrency exchanges, will use its own capital to reimburse customers who lost money in the theft, according to a statement posted on its website on Sunday. The exchange - whose shareholders include 27-year-old chief executive Koichiro Wada, chief operating officer Yusuke Otsuka and two investment firms - said it has been in touch with Japan's Financial Services Authority and the Tokyo Metropolitan Police.

According to Coincheck's account of the incident, an unidentified thief stole 523 million coins tied to the NEM blockchain project, which were trading at about 94 US cents at the time of the hack. It was not until around 11am on Friday morning - about eight hours after the initial breach - that Coincheck staff noticed an alert pointing to a sharp drop in their NEM coin reserves.

The thief was able to seize such a large sum in part because Coincheck lacked basic security protocols. It kept customer assets in what is known as a hot wallet, which is connected to external networks. Exchanges generally try to keep a majority of customer deposits in cold wallets, which are not connected to the outside world and thus are less vulnerable to hacks.

Coincheck also lacked multi-signature, a security measure requiring multiple sign-offs before funds can be moved. While the safeguard failed to prevent a US$65 million heist from Bitfinex in August 2016, NEM's blockchain had multi-signature functions that experts say would have made the theft more difficult.

"I really wish they would have been using NEM's multi-signature contract," Jeff McDonald, vice-president of the NEM Foundation, said in a Youtube video. "That would have probably saved them all these problems." The exchange had not implemented the security measures due to "the difficulty of the technology and a lack of staff able to carry out the task," Wada, who also serves as Coincheck's chief technology officer, told a roomful of unusually combative reporters during a 90-minute press conference at the Tokyo Stock Exchange headquarters that stretched into the early hours of Saturday morning.

The theft sparked a social-media firestorm in Japan, one of the world's biggest cryptocurrency markets, and spurred angry customers to gather in the bitter cold outside Coincheck's headquarters - just an eight-minute walk from the site where Mt. Gox imploded four years earlier.

It was exactly the kind of scene that the country's financial regulator had been hoping to avoid when it introduced a licensing system for cryptocurrency exchanges last April.

Coincheck was four months past its deadline for receiving such a license, but was allowed to continue operating - and advertising on television - while awaiting a final decision from the FSA.

The exchange's fate remains unclear. While Coincheck executives have said they plan to eventually restart trading, they hadn't outlined a timeline by Sunday evening. They did, however, pledge to compensate all 260,000 users impacted by the theft, at a rate of 88.549 yen for each NEM coin.

Coincheck also said it was cooperating with other exchanges in the hope of tracing the missing tokens.

"We know where the funds were sent," Otsuka, the Coincheck COO, said during the late-night press conference. "We are tracing them and if we're able to continue tracking, it may be possible to recover them." The FSA has said it is looking into the incident.

Regardless of how it plays out, the Coincheck theft is likely to push policy makers to enforce stricter security requirements at cryptocurrency exchanges, according to David Shin, a founding member of the Bitcoin Association of Hong Kong and president of the Singapore-based Asia Fintech Society.

"A lot of regulators don't know yet how to regulate this area,'' Shin said. "This episode will definitely get their attention."