This communications protocol was developed by independent hackers and information brokers, it is largely still used by those same groups. The protocol is nearly untraceable as it spreads signal packets across a very wide spectrum band which are chosen through application of a complex cryptographic algorithm based on a dynamic encryption key exchange. Each node has its own cryptographic signature to ensure messages are not intercepted in transit or modified. The protocol is primarily used over subspace, however, at close range conventional radio can be used as well with similar results.
Transient Key Pairs
Each time a communications line is initiated it is done through the use of a transient session key. Each session key is cycled every 5 minutes, if any one of the keys is compromised or unable to be verified for any reason, both senders are notified and the link is terminated, all data is then lost.
Serverless Communication
Each terminal stores its own communications database, connections are made ad-hoc without the need or desire for a centralized server, the protocol accounts for each node acting as both client and server for the communications which are ongoing.
Dynamic Band
The systems disguise their communication packets as normal background radiation, each packet contains data required to jump to the next frequency. Each frequency is chosen to be a reasonable approximation of naturally occurring phenomena for a given area of space. Since the frequency band changes frequently and communications occur through dynamic bursts of data, it is extremely difficult to even locate a signal in use.
Breaking the Encryption
The system uses fractal encryption algorithms to encode and decode data, even Borg advanced decryption routines have not been able to break the algorithms. During the negotiation phase of setting up communication, a dynamic list of secure algorithms is generated and randomly chosen from at each key cycle. Since the encryption algorithm changes with each cycle, it is difficult to break more than one segment of communications. The entire communications link is (that is, the encrypted session data that) is further encapsulated with a different fractal algorithm that would have to be broken before the encrypted session data would be exposed.
Many of the especially use further communications encryption protocols layered inside this protocol, most often steganography to hide covert communications inside banal communications which is then sent using this protocol.
Government Knowledge
The protocol is not illegal, some government operatives use it or a variation of this protocol, however, it is not in general use by any government or organization. Rather it is used by people who know about it. Thus knowledge of how to setup and use the protocol travels by word-of-mouth among the extremely security conscious.
OOC
I am not a security expert, so we assume that holes in my description are filled by some form of techno-babble which makes it secure. As the algorithm is plotted out to be extremely secure and nearly impossible to trace or discover.