Re: preventing header tag spoofing without crypto

I like the idea of including a time stamp in a Tagged: header

I prefer discouraging rearranging the Tagged and Received headers
over declaring that Tagged headers are supposed to copy time stamps
from Received headers.

There is a lot of information in Received headers.  A human being can
easily do sane path verification by reading Received headers.  I suppose
the various path verification proposals are attempting to automate this,
but that discussion is off topic for discussion of the Tagged: header.

I think it makes sense to leave it positional, just like the received
header.  From an implementation viewpoint, it is easy to leave them
alone.  Write your tags, then write the file just like you got it.
Received is prepended when a message arrives.  Maybe Tagged would get
prepended as a message leaves, so it could be above Received in the
headers.  Above or below, it doesn't matter, but next to the Received
header will remove the risk of spoofing.   The fake tags would be
farther in than we are expecting them. The first tags will be closer to
you.  Fake tags will be under the real tags.  So what if all the garbage
gets tagged "not-garbage" when it is sent, the garbage detector will
detect and retag.  The tag checker starts at the beginning of the
message and trusts the first garbage/not-garbage tag it sees, as that
will be the one applied by the last garbage detector that the message
passed through.

Grouping the tagged headers together in a different part of the message
and then having to match them up based on identifying a time-stamp seems
to me like a contrived alternative.

Adding headers at the beginning of the message and leaving the
rest of the message alone is very easy to do.  Matching lines up based
on fields in them is tricky.  The only advantage I see in it is that it
would raise the implementatino comlpexity of standard compliance, and I
do not consider than an advantage, speaking as a lone implementor.




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