Error-Qualifying Signatures

[Scott Collins]

(Oops, forgot to include 'punks, sorry Nick)

Nick Szabo asks:
  >Is a one-way hash function or digital signature possible with the
  >following property: signature verification doesn't just determine
  >the boolean altered vs. pristine, but also shows the picture
  >distance between the altered and original?

This is possible.  It is not a desirable quality for secure-hashes in most
other situations because it compromises the privacy of the original
message.  Hash functions are usually designed specifically to avoid this.


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