Encrypted communication hasn't historically been a serious deterrent for one of the world's premier intelligence services. I like to assume the FBI hires capable detectives, but this recent "crypto frenzy" indicates otherwise.
It's at the bottom of PDF page 3--search for "encryption."
Excerpt:
Unfortunately, changing
forms of Internet communication and the use of encryption are posing real challenges to the
FBI’s ability to fulfill its public safety and national security missions. This real and growing
gap, which the FBI refers to as “Going Dark,” is an area of continuing focus for the FBI; we
believe it must be addressed, since the resulting risks are grave both in both traditional criminal
matters as well as in national security matters.
It is well-known that the FBI director's position is that laws should require the use of back-doored encryption. His position is both ominous and one that has been refuted by a preponderance of experts as dangerous and impractical.