April 5, 2012: On March 11 a team of Turkish police commandos conducted a raid into northern Iraq, going ten kilometers across the border to capture five PKK (Turkish Kurdish separatists) encryption experts. Also captured were laptops and a lot of data and software used to encrypt PKK messages. The encryption team had caused a lot of problems for Turkish intelligence, which could track PKK groups via their wireless transmissions, but could not read the encrypted transmissions. This indicated the use of high-quality encryption, and implied the presence of PKK members who knew this technology and how to use it. Cryptography (or "crypto") is the science of developing and using secret codes to convert text into incomprehensible gibberish, then convert it back (decrypt) it into readable text.
Turkish intelligence sought to identify the PKK encryption team, which appeared to be getting messages from PKK commanders in northern Iraq (delivered by hand, or USB memory stick), then encrypting them and transmitting them to PKK member in Turkey and throughout northern Iraq and parts of Syria. The Turks spent several months tracking down the encryption team, using UAVs as well as electronic monitoring equipment (on the ground and in the air.)
There is a lot of encryption software available on the Internet and commercially. But Turkey, as a nation and NATO member, has access to tools for cracking (decrypting) a lot of these widely available encryption methods. The PKK encryption team appears to have been using high grade encryption that was difficult to decrypt. Thus the capture of the encryption team weakened, for a while, the PKK ability to communicate wirelessly without the Turks reading the messages.
Then again, maybe not. Of the many secrets intelligence agencies keep, those dealing with encryption (and the ability to decrypt) are kept most secret of all. The PKK encryption team may be one of several. Capturing documents and taking the PKK team alive (allowing for interrogation) will reveal much of this to the Turks, but you won't read about the results in the media.
source: Intelligence: Turks Tackle The Crypto Kings