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Re: bike locks and encryption

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Richard Heathfield <invalid@see.sig.invalid> writes:

> Ben Bacarisse wrote:
>
>> Richard Heathfield <invalid@see.sig.invalid> writes:
>> 
>>> Ben Bacarisse wrote:
>>>
>>>> RichD <r_delaney2001@yahoo.com> writes:
>>>> 
>>>>> Something occurred to me recntly - bicycle locks
>>>>> as examples of one way functions, so useful in
>>>>> encryption.  That is, easy to compute in encryption,
>>>>> but intractable for decrytion, lacking the key.
>>>> 
>>>> I don't think that's a good analogy for a one-way function.  Although
>>>> all one-way functions have, in some very abstract sense, a "key" (the
>>>> function's inverse is, I suppose, a key) they are not, usually,
>>>> invertable with some small amount of data acting as a key.
>>>
>>> I think RSA is a counter-example, isn't it? (More on that in a
>>> second.)
>> 
>> I think you (and the OP) might be confusing trap-door functions with
>> one-way functions.
>
> My understanding of a trap-door function is that it's easy to compute in one 
> direction but hard to compute in the other without a crib (for example, 
> RSA).
>
> My understanding of a one-way function is that it's easy to compute in one 
> direction but hard to compute in the other without a crib (for example, 
> RSA).

s/without a crib//

> So yes, I may well be confusing them. ;-)

All things are confusingly similar if you ignore the differences!
Trap-door functions are a special case, and an analogy that is good for
a special case is not always going to be a good one for the general
case.  The existence of a combination to open the padlock is such a huge
special feature, that it makes the analogy more confusing then helpful.

-- 
Ben.

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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

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