The general idea of according
access only to somebody who owns something is really good
but not always readily applicable. Take the example of early
computers. Hardware costs and lack of a widespread standard
would have made the creation of a physical lock impractical,
but above all, the availability of far cheaper and handier alternatives
delayed that idea until recent times.
The cheaper and handier alternative is relying on something that
the user knows rather than owns. A physical key has to be
crafted for a speci?¬?c lock and distributed to the users. You have
to remember to bring it along; it can break; and if for some reason
the lock has to be changed, one has to go through the cycle
again. On the other hand, knowing one password is one of the
most agile things that can be devised. If the enemy stripped you
of everything and you manage to escape from their prison, you
can always reenter friendly territory by shouting the passphrase
of the day. If the deal would be that for entering friendly areas
you have to show a certain medallion currently in the pocket of
a prison guard, you??™d be in trouble.
The ?¬?rst computer access control was performed by passwords,
strings of characters that can be entered via the machine input
peripherals.
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