A Clever 'Work Around' for any Cryptography Export Regulations

An MIT professor has proposed a new method of providing for secure data exchange on the Internet - one that uses a technique that he argues lies outside the control of US officials struggling to maintain a tight hold on encryption enabled software. Ronald Rivest (MIT), relying on an ancient threshing floor analogy, calls his process 'chaffing and winnowing.'

Using his technique, messages are sent on the Net in a combination of good packets (wheat) and bad packets (chaff). The wheat packets can be distinguished - or winnowed - from the chaff packets by the authentication code, or MACs, appended to them.

If a packet meets the authentication code, it is valid; if it fails, it is not valid and is thrown out. They key to the authentication code is known only by the sending and receiving parties.

Rivest notes that authenticating data is not considered encryption, and thus his chaffing and winnowing process would avoid US restrictions on the export of encryption technology. Furthermore, he writes: "Access to authentication keys is one thing that government has long agreed that they don't want to."

Rivest's paper, reported in Sunday's New York Times, has a clear political point: "As a consequence of the existence of chaffing and winnowing," he writes, "one can argue that attempts by law enforcement to regulate confidentiality by regulating encryption must fail, as confidentiality can be obtained effectively without encryption." 


Last Revised : 01 July 2014