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Puzzling

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    $\begingroup$ But the key would still be stolen. Then how will Jane open the box? $\endgroup$
    – Devsman
    Commented Mar 30, 2016 at 16:31
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    $\begingroup$ Is there anything in this puzzle that prevents Mike from driving the key over to Jane the next time they meet? I mean, he still mails her the ring in the padlocked box, she just can't open it until he gets there too. $\endgroup$
    – Bradley Uffner
    Commented Mar 31, 2016 at 13:29
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    $\begingroup$ Easy: send the ring in a padlocked box. The padlocked box isn't in a padlocked box, so it gets stolen, but the ring doesn't, so just the ring arrives. =P $\endgroup$
    – Mike Kellogg
    Commented Mar 31, 2016 at 16:51
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    $\begingroup$ @MikeKellogg I see what you did there ;) $\endgroup$
    – cst1992
    Commented Mar 31, 2016 at 19:45
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    $\begingroup$ Does Alice and Bob... sorry, Jane and Mike... have a second channel of communication where they can exchange information in a safe manner? If not, the problem is entirely unsolvable because a Man in the Middle can impersonate Jane entirely. There is no difference between Jane and the MitM as far as recipients go. Jane and Mike need a secure channel or a previously agreed-upon shared secret, otherwise this problem is unsolvable. $\endgroup$
    – MichaelK
    Commented Apr 4, 2016 at 10:38