How do you know they were stolen documents?

[ProSense]

33. Right, and you're assuming that it has no relation to the statement that follows.

Mr. Miranda was in Berlin to deliver documents related to Mr. Greenwald’s investigation into government surveillance to Ms. Poitras, Mr. Greenwald said.

Ms. Poitras, in turn, gave Mr. Miranda different documents to pass to Mr. Greenwald.

Those documents, which were stored on encrypted thumb drives, were confiscated by airport security, Mr. Greenwald said.

All of the documents came from the trove of materials provided to the two journalists by Mr. Snowden.

The British authorities seized all of his electronic media — including video games, DVDs and data storage devices — and did not return them, Mr. Greenwald said.

Which is why I asked: Did she gave him encrypted recipes or something unrelated ("Those documents...were confiscated&quot to deliver?

Despite the context of the text, you are assuming that he was returning with encrypted document completely unrelated to Snowden's leak.