From an arbitrary given channel code over a discrete or Gaussian memoryless
channel, we construct a wiretap code with the strong security. Our construction
can achieve the wiretap capacity under mild assumptions. The key tool is the
new privacy amplification theorem bounding the eavesdropped information in
terms of the Gallager function.Comment: 5 pages, no figure, IEEEtran.cls. Submitted to 2010 IEEE ISI