The battle lines are drawn. Congress has again taken up the issue of electronic surveillance, trying to rein in the excesses of the "Protect America" Act. A central point of contention: deciding whether telecommunications companies will be granted immunity for their complicity in the government's warrantless wiretapping scheme.

Less than ten years ago, two respected research engineers wrote a book about privacy and telecommunications. In large measure, that book, by Whitfield Diffie and Susan Landau, focused on cryptography -- the science of encrypting information -- and the Clinton administration's insistence on installing "escrow" devices, or backdoors into encryption systems, that only it could access.