You could think of Riffle as a smarter and hardened Tor network.
Although many privacy conscious users have taken to the Tor network for securing their online privacy, the system is not hack-proof, with motivated state actors, and hackers able to compromise the security of thousands of users.
So as to strengthen and improve security related concerns, researchers from EPFL and MIT have developed Riffle, an anonymity network which is as secure as any one of its servers.
The secret of its secure networking lies in the use of a mixnet wherein servers rapidly switch the order of messages without the use of a public key.
The public key is replaced by a verifiable method of shuffling messages across servers during handshaking while an authentication encryption which validates the genuineness of the message takes care of the rest. Thus even if a single server has been compromised by a hacker the network as a whole still remains secure.
As you might imagine, with the technique being developed by MIT, it is brilliantly efficient to the point that transferring nodes takes 1/10th of the time it would take on a conventional anonymity network.
This is critical since typically many such nodes are but standalone computer of users on the network and not dedicated hardware heavy servers. Thus, traffic management is key.
Given its mix of hardened security with minimal overheads, it could soon be the communication of choice for privacy concerns netizens.