FYI -- Only a few more bits to go... Quantum Threat to Our Secret Data New Scientist (09/13/07) Vol. 195, No. 2621, P. 30; Graham-Rowe, Duncan Quantum computing's ability to decrypt the codes that safeguard banking, e-commerce, and business data has taken a step closer to realization with the development of quantum computers that can run Shor's algorithm by two research groups working independently. RSA is an example of a highly common encryption system that can be defeated by Shor's algorithm. RSA involves a widely distributed public key for encrypting messages and a secret private key for decrypting them, and the trick to solving the private key is to work out the large prime numbers that produce the key when they are multiplied together. Shor's algorithm dramatically reduces the time it takes to find the prime factors by searching for telltale patterns in remainders when a key is divided by a prime factor, but quantum computation is essential for performing the massive number of calculations that the algorithm requires to be successful. The first quantum implementation of Shor's algorithm involved the manipulation of nuclear spin, while the more recent experiments--one led by Andrew White at Australia's University of Queensland and the other by Chao-Yang Lu of the University of Science and Technology of China--used quantum photonic computers. Photon pairs were produced with femtosecond lasers and passed through polarizing bismuth borate crystals to generate entangled qubits, which were coaxed by optical devices to run Shor's algorithm to factor the number 15 into its prime components. IT security specialist Bruce Schneier calls the development of techniques to run the algorithm using standard lab optics a significant achievement that could spell trouble for encryption down the road. White contends that cryptography would need to be fundamentally rethought if quantum calculations for much larger numbers could be carried out. "There are paths to a fully scalable quantum computer," he notes.