Hi John:
Your example is, as described by Doug Nix, defeat resistance, not tamperproof
(see the definitions). Tampering cannot be safeguarded, except, maybe, with a
safe (which is also defeat resistant).
Best regards,
Rich
From: John Woodgate
Sent: Tuesday, April 9,
Hi Doug:
Defeat resistance is not tamperproof.
I agree that defeat resistance is a legitimate safety requirement, but not so
for tamperproof (at least not with the definitions I provided).
Best regards,
Rich
From: Douglas Nix
Sent: Tuesday, April 9, 2019 11:23 AM
To:
Rich,
Respectfully, I have to disagree. ISO 14119, Safety of machinery — Interlocking
devices associated with guards — Principles for design and selection,
specifically addresses defeat resistance in interlocking devices. This is
vital, since defeat resistance is an important aspect of
'Tamperproof' is like 'fireproof' or 'foolproof' - a pure illusion;
misplaced human ingenuity knows no bounds. But measures against
successful tampering are surely not outside the scope of safeguarding.
For example, a soda-machine has parts designed so that they can be
assembled together with
Standards need not – indeed should not -- address nefarious activity on the
part of the user. And, standards need not address tampering (defined
previously) as there can be no end to the extent of tampering. The requirement
for “tamperproof” is beyond the scope of safeguarding a user
Yes, that might the point of fitting such screws, but the standard would
then have to define both such screws and the specific assessments/tests that
would be necessary for them to be deemed acceptable/certifiable - but, of
course, it actually says nothing about either of those matters.
John E
Per: 3 to engage secretly or improperly in something.
Wouldn't improperly be the key word, as it may expose a hazard?
Larry Merchell
From: John Woodgate
Sent: Tuesday, April 9, 2019 2:36:47 AM
To: EMC-PSTC@LISTSERV.IEEE.ORG
Subject: Re: [PSES] Tamper-proof
Yes, that is clearly the point of fitting t-p screws.
Best wishes
John Woodgate OOO-Own Opinions Only
J M Woodgate and Associates www.woodjohn.uk
Rayleigh, Essex UK
On 2019-04-09 15:56, Larry Merchell wrote:
Per: 3 to engage secretly or improperly in something.
Wouldn't improperly be the key
IR-3 Internal Regulations for writing standards issued by CENELEC (which
is roughly the same as IR2 in IEC) gives information on how to write
standards, and shows clearly that the Introduction should be informative:
From IR-3
Introduction
13.1 Purpose or rationale
The introduction provides
We are not so far apart. You say that the text should not have appeared
in a numbered clause that might be assumed to be normative. I say that
it would be better not to have a numbered clause because it might seem
to be normative.
I think that few would assume that the normal INTRODUCTION
John W
When something that ambiguous, and which that could be construed as being a
requirement, is placed in a prominent position in a standard, regardless or not
of whether the clause in question is numbered, then it is obvious that it will
(as it has done) raise issues and questions as to
I think that the major point is that Clause 0 is purely advisory. It
seems reasonable in an advisory text to mention means to deter
operations that might compromise safety, without going into exhaustive
detail. It would seem harmless, so not worthy of suppression.
I wouldn't have given the
Rich
Thanks for laying out the main definitions of “tamperproof”, and for your view
on why my “story” is not an example thereof (it was only the one that I had
“to-hand” at the time, and there must be many others J) .
Maybe, therefore, similar definitions/explanations should have been
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