Enlarge / Michael Cohen leaving the United States District Court Southern District of New York on May 30, 2018 in New York City. A letter today revealed that the FBI had recovered over 700 pages of messages and call logs from encrypted messaging apps on one of two BlackBerry phones belonging to Cohen. (credit: Getty Images)

In a letter to the presiding judge in the case against Michael Cohen, President Donald Trump’s long-time personal attorney, the US Attorney’s Office for the District of Southern New York revealed today that it had obtained additional evidence for review—including a trove of messages and call logs from WhatsApp and Signal on one of two BlackBerry phones belonging to Cohen. The messages and call logs together constitute 731 pages of potential evidence. The FBI also recovered 16 pages of documents that had been shredded, but it has not yet been able to complete the extraction of data from the second phone.

The letter to Judge Kimba Wood stated that “the Government was advised that the FBI’s original electronic extraction of data from telephones did not capture content related to encrypted messaging applications, such as WhatsApp and Signal… The FBI has now obtained this material.”

This change is likely because of the way the messages are stored by the applications, not because the FBI had to break any sort of encryption on them. WhatsApp and Signal store their messages in encrypted databases on the device, so an initial dump of the phone would have only provided a cryptographic blob. The key is required to decrypt the contents of such a database, and there are tools readily available to access the WhatsApp database on a PC.