More fun publisher surveillance:
Elsevier embeds a hash in the PDF metadata that is *unique for each time a PDF is downloaded*, this is a diff between metadata from two of the same paper. Combined with access timestamps, they can uniquely identify the source of any shared PDFs.
@derwinmcgeary
it decodes with base85, but it's not Unicode. not sure if that's meaningful
@derwinmcgeary
yeah, I thought so too but don't know where to start reverse engineering it :/