Groups | Search | Server Info | Keyboard shortcuts | Login | Register [http] [https] [nntp] [nntps]

Groups > comp.programming > #4821

Re: bike locks and encryption

Show all headers | View raw

On October 7, Kaz Kylheku wrote:
>> bicycle locks as examples of one way functions, so useful in 
>> encryption.
> 
> All the bicycle locks with which I am familiar are not one-way functions in any
> sense. 

Think harder.

> To open the lock, you must show that you either know a secret (the
> combination) 

Thus, without the combination, it's infeasible.

> Mechanical locks evaluate this function mechanically, powered by the user. For
> instance, you rotate some dials to bring them to some configuration, and then
> have the lock evaluate the matches? predicate by trying to pull the lock open.
> The lock either says "True" by separating or "No" by refusing to separate.

well yeah
And you have to try every one.

But you missed the point completely.
Think about trying to close (mate) an opened lock, without the 
combination.  What's the complexity?  There's the one way function aspect.

--
Rich

Back to comp.programming | Previous | Next — Previous in thread | Next in thread | Find similar | Unroll thread

Thread

bike locks and encryption RichD <r_delaney2001@yahoo.com> - 2014-10-06 23:28 -0700
  Re: bike locks and encryption Ben Bacarisse <ben.usenet@bsb.me.uk> - 2014-10-07 11:39 +0100
    Re: bike locks and encryption Richard Heathfield <invalid@see.sig.invalid> - 2014-10-07 11:53 +0100
      Re: bike locks and encryption Ben Bacarisse <ben.usenet@bsb.me.uk> - 2014-10-07 16:24 +0100
        Re: bike locks and encryption Richard Heathfield <invalid@see.sig.invalid> - 2014-10-07 21:26 +0100
          Re: bike locks and encryption Ben Bacarisse <ben.usenet@bsb.me.uk> - 2014-10-08 01:34 +0100
          Re: bike locks and encryption RichD <r_delaney2001@yahoo.com> - 2014-10-07 23:16 -0700
      Re: bike locks and encryption RichD <r_delaney2001@yahoo.com> - 2014-10-07 23:27 -0700
  Re: bike locks and encryption RichD <r_delaney2001@yahoo.com> - 2014-10-07 13:57 -0700
    Re: bike locks and encryption Kaz Kylheku <kaz@kylheku.com> - 2014-10-07 21:21 +0000
      Re: bike locks and encryption "BartC" <bc@freeuk.com> - 2014-10-07 22:33 +0100
        Re: bike locks and encryption Jongware <jongware@no-spam.plz> - 2014-10-08 15:51 +0200
  Re: bike locks and encryption Kaz Kylheku <kaz@kylheku.com> - 2014-10-07 21:10 +0000
    Re: bike locks and encryption RichD <r_delaney2001@yahoo.com> - 2014-10-07 23:34 -0700
      Re: bike locks and encryption Kaz Kylheku <kaz@kylheku.com> - 2014-10-08 14:10 +0000
        Re: bike locks and encryption RichD <r_delaney2001@yahoo.com> - 2014-10-10 18:33 -0700

csiph-web