The Holy Grail of cryptography is a code so complex that even the most intense and sustained computing attack cannot crack it.
Cryptographers reach for that goal by adding bits to a code's "secret key" -- each time effectively doubling the security it affords. Inevitably, processors catch up.
But IBM researchers think they might have found a solution.
"We are not reinventing encryption," said Nabil Amer, a research scientist at IBM's Almaden Research Center, in San Jose, California. "Rather, we are using quantum physics to provide an absolutely secure method of key distribution."
Quantum physics is an arcane, and mostly theoretical, realm of science that deals with the physical properties of molecular structures. The IBM technique adds an extra layer of security to conventional public-key-encryption techniques by translating the bits in a key into quantum bits, or qubits.
A bit in a standard computer is represented by a single digit that is either 0 or 1. But a qubit, which can be represented by an atom or photon, can exist simultaneously as 0 and 1. The qubits change state according to a complex mathematical formula.
The heady scheme increases the number of possible keys by an exponential factor.
IBM, Japan's NTT, Los Alamos National Labs, and British Telecom are all developing methods for using quantum physics to transfer encrypted messages.
At Los Alamos, quantum-information team leader Dr. Richard Hughes is running a quantum encryption prototype to develop systems for satellite and military purposes. The IBM researchers are exploring quantum encryption for possible use in banking and commercial applications.
One researcher said current key lengths will protect sensitive information for the foreseeable future, removing the need for quantum physics-driven codes. Pretty Good Privacy, a free personal encryption program, can create a secret key up to 2,048 bits in length.
"I believe that we have solved the problem of how to get information securely from point A to point B," said Phil Karn, an encryption expert for the mobile telecommunications company Qualcomm.
