Re: [Electronics_101] Re: Electronic Lock Protocol
- I suspect that this is not the secret that Kerim is having us guess. The technique needs to be able to be performed by kids and in my experience getting timing right is not for (always) impatient little hands.
On Apr 6, 2013, at 6:09 PM, Donald H Locker wrote:
> In that case, the time between digit entry becomes the secret "code". For instance, two digits quickly, pause, one digit, pause, three digits quickly.
[Non-text portions of this message have been removed]
- I like it; very clever and far more difficult to reproduce than a simple rhythm.
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----- Original Message -----
> From: "Kerim F" <ahumanbeing2000@...>
> To: "Electronics 101" <Electronics_101@yahoogroups.com>
> Sent: Monday, April 8, 2013 7:45:38 AM
> Subject: [Electronics_101] Re: Electronic Lock Protocol
> --- In Electronics_101@yahoogroups.com, "Kerim F"
> <ahumanbeing2000@...> wrote:
> > --- In Electronics_101@yahoogroups.com, "Kerim F" <ahumanbeing2000@>
> > wrote:
> > >
> > > For those who have free time, here is a protocol to find out for
> > > the following situation. When I designed an electronic lock for
> > > the door of my house, I had a problem that there would be always
> > > one or more friends by the door (with me) who, naturally, were
> > > curious to find out its secret digits. So I had, for this special
> > > situation, to create a protocol that prevented a curious observer
> > > to repeat what I did every time I open my door. I tested it with
> > > many friends and for too many times and all failed opening my door
> > > in their turn. Could you guess how this protocol was (or could
> > > be)? I use it for a few years only, about 30 years ago.
> > >
> > > Kerim
> > >
> > May I add that the power of the simple protocol I did is that it is
> > not known by others; after all I worked on it for my need only ;) I
> > mean it is good as long it is unknown by strangers otherwise it
> > loses most of its beauty ;)
> > Kerim
> Hi all,
> Since I may have a limited time before the Internet here sleeps again
> (for another few days perhaps), I will address this post to all of you
> instead of replying each.
> As you already noticed, one line was enough for my question but its
> answer needs much more. Please be patient. ;)
> (1) ) At the first key press, the lock board is energized by its 4 AA
> (2) There are three timers that limit:
> (2a) the shortest time for accepting a pressed key, otherwise the
> entries are reset (see [2c]),
> (2b) the entry time after which the controller resets the code
> (2c) the idle time between trials, during which pressing a key is
> (3) The last key is fixed (as #) to open the lock if:
> (3a) the 6 digits of the code were all received with the proper
> (3b) AND the key is pressed during the timer [2b], see above.
> Now the fun starts ;)
> The lock controller reads then accepts or ignores one entry at a time.
> For example, let us assume the secret code is 1, 2, 3, 4, 5 and 6.
> And let us assume that 15 keystrokes could be done; see [2a] and [2b]
> The following sequences are all valid:
> 6, 1, 0, 2, 7, 4, 4, 3, 1, 4, 9, 5, 6, 8, #
> Note: 6, (1), 0, (2), 7, 4, 4, (3), 1, (4), 9, (5), (6), 8, #
> 8, 7, 1, 2, 0, 6, 3, 4, 3, 5, 9, 6, 0, 1, #
> Note: 8, 7, (1), (2), 0, 6, (3), (4), 3, (5), 9, (6), 0, 1, #
> 1, 3, 2, 2, 9, 0, 4, 3, 4, 7, 7, 5, 8, 6, #
> NOTE: (1), 3, (2), 2, 9, 0, 4, (3), (4), 7, 6, (5), 8, (6), #
> Obviously, the number of entries could be from 7 (including #) to 15.
> If I also took advantage of the idle timer [2c] during which more
> redundant keys could be pressed, things got more complicated for the
> curious eyes. Practically, there is no limit of how to confuse those
> who stand by the lock so that they find hard repeating all entered
> keys since they have no idea about the reader protocol and its 3
> timers and their limits. Naturally, no one succeeded opening the door
> in his turn while I was telling him `fairy tales' about how the
> magical lock works ;)
> The kids have also managed fooling their friends as well ;)
> As I pointed out earlier, the secret code AND how the keys are
> accepted, form BOTH the strength of the lock. And, when I used it, it
> wasn't possible, unlike now, recording the entered keys by a video
> (mobile) camera for example ;)
> For instance, when I was alone, 1, 2, 3, 4, 5, 6, # were all what I
> needed to press in order to open the lock.
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