Paranoia is cryptography's occupational hazard. Recently there has been a small rash of complaints about unwanted assignment of penet pseudonyms. The first reported was simply a description, the most recent assumed that the assignment was the result of someone trying to find out mappings in the penet database. This clear illustration of paranoia setting in demonstrates the nature of the hazard. The effect of paranoia is self-delusion of the following form--that one's possible explanations are skewed toward malicious attacks, by individuals, that one has the technical knowledge to anticipate. This skewing creates an inefficient allocation of mental energy, it tends toward the personal, downplaying the possibility of technical error, and it begins to close off examination of technicalities not fully understood. Those who resist paranoia will become better at cryptography than those who do not, all other things being equal. Cryptography is about epistemology, that is, assurances of truth, and only secondarily about ontology, that is, what actually is true. The goal of cryptography is to create an accurate confidence that a system is private and secure. In order to create that confidence, the system must actually be secure, but security is not sufficient. There must be confidence that the way by which this security becomes to be believed is robust and immune to delusion. Paranoia creates delusion. As a direct and fundamental result, it makes one worse at cryptography. At the outside best, it makes one slower, as the misallocation of attention leads one down false trails. Who has the excess brainpower for that waste? Certainly not I. At the worst, paranoia makes one completely ineffective, not only in technical means but even more so in the social context in which cryptography is necessarily relevant. The problem with assignment of penet ID's was not due to any malicious intervention, but rather someone subscribing to the list with a penet address. Since the list doesn't alter the headers much at all, the originator of a list message is sending indirectly to penet, forwarded through toad. I've swapped the address so this shouldn't happen again. Eric