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PMCHECK(1)		    General Commands Manual		    PMCHECK(1)

NAME
       pmcheck	- check	veracity and applicability of signatures in news arti-
       cles.

SYNOPSIS
       pmcheck [newsgroups|user] [file]

DESCRIPTION
       Pmcheck accepts an article from the named file (or  standard  input  if
       not  specified),	and performs certain checks against digital signatures
       present in X-Auth: headers in the news articles.	There are  two	common
       modes  of  use  of pmcheck, and these are described separately for sim-
       plicity,	even though there is considerable ability to mix-and-match.

       The first use is	when a person is reading news, and sees	an article and
       wishes to check whether the article is an approved posting to a	moder-
       ated  newsgroup,	 or  an	 approved posting from a particular individual
       user. Piping the	article	through	pmcheck	will give a list of valid sig-
       natures (or signatures which couldn't be	checked	because	 corresponding
       PGP  public  keys  were unavailable), and of course generate error mes-
       sages for invalid signatures, which indicate either forged  or  altered
       articles.  Any alteration might have been intentional, but bear in mind
       the possibility that an alteration could	have been an artifact  of  the
       news system, despite precautions	against	this.

       The  second use,	and the	reason for the existence of the	PGP Moose sys-
       tem, is when an article is automatically	checked	upon receipt by	a des-
       ignated news hub. In this case, a  moderated  newsgroup	or  user  name
       (represented  by	 an electronic mail address) will be specified,	and it
       is considered an	error if there is no corresponding X-Auth: header,  or
       if  for	any  reason  it	doesn't	check out. Furthermore,	there can be a
       configured file which lists pairs of newsgroup/user names,  and	corre-
       sponding	PGP user IDs who are allowed to	authorise such postings.  Even
       a  valid	 signature  from  an individual	who is not listed in this file
       will be considered an error. All	X-Auth:	headers	 will  be  checked  if
       their newsgroup/user name appears in the	checking file, the only	way in
       which  the argument is special is that such a header for	that newsgroup
       or user must appear.  The intention is that  any	 article  which	 fails
       this  authentication  process will be reported to the user or newsgroup
       moderator(s), and might be automatically	cancelled. This	 is  to	 react
       quickly to spamming attacks on moderated	newsgroups.

EXIT STATUS
       Pmcheck	returns	 an  exit  status of 0 if everything is	all right, and
       non-zero	otherwise.  In particular, an exit status of 1 means that  the
       article	was  not approved with the PGP Moose when it should have been,
       and a status of 2 is returned for all other authentication problems.

SEE ALSO
       pmapp(1), pmcanon(1) for	a description of the fields which go into  the
       signature calculation, the PGP User's Manual, the PGP Moose README file
       for an understanding of how it all hangs	together.

BUGS
       Currently  pmcheck  always  allows cancel messages to pass, despite the
       fact that pmdaemon always  authenticates	 them.	The  potential	conse-
       quences	of  an	automated cancellation-war were	simply too horrible to
       contemplate.

AUTHOR
       Greg Rose, RoSecure Software.

				   PGP Moose			    PMCHECK(1)

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