Nowadays we see that countries like China and Iran detect and block all encrypted connections as a way to prevent their citizens from communicating over the Internet freely. Although encryption provides the highest level of data protection, still we can't hide the fact that the communication is encrypted due to the randomness introduced by the encryption. Rivest wrote a paper in 1996 titled "Chaffing and Winnowing: Confidentiality without Encryption". The basic idea is that Alice and Bob share an encryption key for MAC not encryption. When Alice construct a packet, a MAC is calculated on the packet and a secret key. The MAC is appended to the packet and is send to Bob. Communication is in cleartext so anyone observing the channel can sniff the data. Now if another stream of data from two other persons (mentioned as David and Elien in the paper) is mixed with the stream of Alice and Bob, only Alice and Bob can recover their own packets because only these two entities know the MAC key. The same goes for the other parties David and Elien.
My question is, is their any practical implementation of the above scheme because reading the paper, it is clear that if sufficiently large streams are multiplexed together, it would be impossible for anyone to recover the exact packets of a stream without knowning the MAC key and hence for any government it would be impossible to block any network traffic if a large number of volunteers join and multiplex this theoritical network.