Signing ascii text

Eric Messick eric at
Wed Dec 23 11:57:58 PST 1992

I would like to argue for a weaker ascii text signature function in
PGP in addition to the current one.  It would canonicalize a file by
turning all sequences of white space into a single space and trimming
leading and trailing whitespace from the file before computing the
hash.  This clearly involves some major changes to the file, allowing
many files to hash to the same value, but a human would presumably
consider all of those files to have the same information content.  The
only case that I can think of where the information content of the
message could be changed with the signature remaining valid is if
information was contained in the pattern of whitespace in the file.
This should make the signature robust to most of the changes that a
mailer could make.  I would not advocate extending this to any
non-whitespace characters.

-- eric messick
eric at

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