MADRID (Reuters) – One of banking’s most wanted whistleblowers, Frenchman Herve Falciani, has picked unlikely new weapons to fight money-laundering and fraud – cryptocurrency and the blockchain technology behind it.

Living in self-imposed exile in Spain, the former HSBC systems engineer whose leaks of client data triggered a series of high-profile tax investigations is working with Spanish academics and fintech experts on a cryptocurrency he thinks regulators could embrace.

He plans to launch an “ethical” crypto-token, called Tabu, making it traceable thanks to a certificate showing its clean record. Tax-dodgers, shady businesses, hackers and criminals often use cryptocurrencies to hide their transactions.

“What happens with any innovation or any technology is that it can be used in the bad way or maybe used in a friendly way with a social impact, positive social impact,” Falciani, who is part of a witness protection programme, told Reuters in an interview in a neutral location in Madrid.

Falciani argues that blockchain – the technology behind cryptocurrencies that verifies encrypted transaction records and shares them across a network – can add transparency to any electronic transaction, helping the fight against fraud.

The project is developed by a non-profit entity Tactical Whistleblowers founded by the Monaco-born IT engineer in Spain. The group includes various academics, mainly mathematicians, from the Valencia Polytechnic University in eastern Spain.

Last year, which marked a decade since the “Falciani List” leak, the Spanish high court rejected Switzerland’s second extradition request for Falciani, who said the renewed public attention helped generate investor interest in Tabu.

“If it wasn’t for that, you wouldn’t have heard about the cryptocurrency project I was into,” said Falciani, who earns his living with consultancy fees.

He has 5 million Tabu tokens, valued at 2 million euros ($2.3 million), ready to be offered to investors, pending a go-ahead from the Spanish market regulator. After raising 1.3 million euros, the project still requires about 2 million euros to complete, he said.

He is also preparing to launch a new blockchain-based initiative that will cross-check electronic procurement contracts for public administrations, an area often plagued by overbilling and other fraudulent schemes in many countries.

“Technically and financially this opens the doors to improve the procurement systems. Because in public procurement we have a huge opportunity to spare money,” he said of the new system, called Aletheia, a Greek term for “disclosure”. It was inspired by the SWIFT system for interbank money transfers and messaging.

“Fake information is the basis of any kind of fraud … The same way that we have to deal with fake news, the same technology can applied to fake invoices,” he said of the cross-checks designed to remove most fraud risks.

Falciani said he has few regrets and considers the time he spent in jail awaiting extradition an experience that opened new perspectives.

“Jail, it’s supposed to be a nightmare to everyone and to me it was a means for an end … Even there, I learned many things,” he said.