[math-fun] well known but no references?

A last minute talk was given this year at the Finite Fields and their applications conference (http://www.deakin.edu.au/scitech/eit/fq8/) claiming to break several discrete logarithm based public key cryptosystems. Their break consisted of basing the cryptosystems in Z/(p^n)Z where the discrete logarithm was known in Z/pZ. I had thought that this was a well known result, just a simple extension of Hensel lifting (it's a fun number theory exercise to work out the details), but haven't found any references to 'exponential Hensel lifting' in any of the usual places. Google turned up nothing either. Does anyone know of any references to this? Amy Johnston