"Prudent Engineering Practice for Cryptographic Protocols"
Martin Abadi and Roger Needham
June 1, 1994. 25 pages.

We present principles for designing cryptographic protocols.
The principles are neither necessary nor sufficient for
correctness.  They are however helpful, in that adherence to them
would have prevented a number of published errors.

Our principles are informal guidelines; they complement formal methods,
but do not assume them. In order to demonstrate the actual applicability
of these guidelines, we discuss some instructive examples from the
literature.