Google, Microsoft, Yahoo and other tech giants knew of the existence of the Internet surveillance program PRISM, they just didn't know it was called that, according to the NSA's top lawyer.

Rajesh De, the spy agency's general counsel, said that the companies knew that the NSA was collecting data from them. This revelation comes after months of repeated — and very similar — denials by the tech companies.

"Prism was an internal government term that as the result of leaks became the public term," De said at a hearing with the Privacy and Civil Liberties Oversight Board on Wednesday, according to The Guardian. "Collection under this program was a compulsory legal process that any recipient company would receive." Meaning, any company that received data requests, which would include tech companies, would have been subject to PRISM.

When De was asked whether the NSA collection happened with "full knowledge and assistance of any company from which information is obtained," he simply answered: "Yes."

PRISM was one of the first revelations to come out of the documents leaked by Edward Snowden to The Guardian and The Washington Post. And, in some ways, it's still shrouded in some mystery.

When it was first revealed, it was unclear how the program actually worked. Does the NSA have direct access to the companies servers? Or does it receive data through more indirect means?

As it turned out, the NSA can't just press a button and read a target's emails. The NSA has to get a Section 702 order (which refers to the part of the law which serves as its legal basis) and then the companies comply with it, delivering the data in different ways.

Privacy and security researcher Ashkan Soltani theorized the NSA got access through some sort of data ingestion API system, or with company-run dropboxes.

Google revealed that it gave access to its data through a Secure FTP server, and sometimes even by hand, as reported by Wired. Facebook, on the other hand, refused to disclose how it complies with NSA requests.

Snowden himself clarified that "the provenance of data is directly from their servers," but "it doesn’t mean that there’s a group of company reps sitting in a smoky room, palling around with the NSA and making back-room deals to give stuff away," he said during his talk at TED on Tuesday.

"When we talk about this information and how it’s given, it’s given by the companies themselves, it’s not stolen," he added.

That is in line with what De said today, Google has revealed, and with Soltani's scenarios. When the NSA requests data, the companies have to respond somehow, just like they respond to normal law enforcement requests. Facebook, for example, provides authorities with a portal where they can login and request data.

Microsoft appears to offer something similar. A 22-page document leaked by the whistleblower site Cryptome contains a screenshot of Microsoft Confidential, which seems to be an online portal for accessing user information.

A screenshot from the Microsoft "Global Criminal Compliance Handbook."

The NSA declined to offer any comments or clarifications on De's words. And when Mashable asked the NSA specifically whether Microsoft Confidential is the company's implementation of PRISM, spokesperson Vanee Vines didn't respond.

Apple, Yahoo, FB, Microsoft and Google could not immediately be reached for comment.