In late 2014, an anonymous source secretly leaked to a German newspaper reporter nearly four decades of confidential and proprietary data about shell companies registered by the multinational Panamian based law firm Mossack Fonseca.

The German newspaper contacted the International Consortium of Investigative Journalists (ICIJ) who assembled more than 100 other international news outlets, including the U.S. based McClatchy newspapers, to secretly review and investigate the massive amount of leaked data. Last Sunday, journalists in these news outlets began publishing stories on the so-called Panama Papers. While offshore shell companies have legitimate business purposes, these journalists reported that many of the 214,000 companies were formed to mask the true owners, citizens from more than 200 countries and territories worldwide.

Mossack Fonseca’s co-founder confirmed the leaked data was authentic, and alleges the firm’s records were externally hacked. The firm has already notified its clients and law enforcement of the unauthorized access to confidential and proprietary documents and information, which includes corporate and financial records, emails and passports.

No one, including Mossack Fonseca and its partners, has been directly accused of breaking any laws. However, just being linked to these offshore companies has already had some dramatic repercussions. Iceland’s prime minister of Iceland and the head of global corruption watchdog Transparency International’s Chile branch have resigned. Several other politicians, professional soccer officials, celebrities and professional athletes and their families are under scrutiny. United States and European law enforcement officials announced investigations into the leaked data to determine whether tax or other laws in their countries were broken.

According to the McClatchy newspapers, the only U.S. newspaper involve in ICIJ’s efforts, thus far about 200 scanned U.S. passports, 3,100 companies were tied to people in the U.S., and about 3,500 shareholders of offshore companies with U.S. addresses listed have been found in the leaked data. However, as yet, very few U.S. residents have been publicly identified.

Encryption and anonymity technology played a significant role in keeping the Panama Papers project secret for more than a year. Encrypted channels were used by the original whistleblower to originally contact the German reporter. During the challenging process of transferring, indexing and analyzing the data, ICIJ journalists working on the project created a secure database to enable them to access the data and communicated with each other about their findings. In fact, ICIJ and the news outlets have no current plans to release the 2.6 terabytes of leaked data comprised of 11.5 million documents as much of the data is sensitive and relates to private individuals. To date, the group’s reporting has focused on public figures linked by the data to offshore companies.