From an article by James Bamford "Last year, Greenwald found himself unable to open the encryption on a large trove of secrets from GCHQ—the British counterpart of the NSA—that Snowden had passed to him. So he sent his longtime partner, David Miranda, from their home in Rio to Berlin to get another set from Poitras. But in making the arrangements, The Guardian booked a transfer through London. Tipped off, probably as a result of GCHQ surveillance, British authorities detained Miranda as soon as he arrived and questioned him for nine hours. In addition, an external hard drive containing 60 gigabits of data—about 58,000 pages of documents—was seized. Although the documents had been encrypted using a sophisticated program known as True Crypt, the British authorities discovered a paper of Miranda’s with the password for one of the files, and they were able to decrypt about 75 pages. (Greenwald has still not gained access to the complete GCHQ documents.)"