[plug] [semi-OT] Public/private keys?

[Luke Dudney]

Yes, that's true. However, asymmetric encryption algorithms are selected 
to be such that trying to compute this inverse function would take 
billions or gazajillions of times longer than the other way around.
As a very basic example, modern CPUs are very good at multiplying 
numbers together, but are very poor at division.
You could employ an encryption algorithm that multiplies two numbers 
together, and to crack that encryption would require you to then divide 
the result to get the original numbers, which would take far longer.

Cheers
Luke


Andrew Furey wrote:

>Hi all,
>
>Just a general question on the principals of public
>key cryptography.
>
>I understand that encrypting a document with the
>private key can only be decrypted by the matching
>public key, and vice versa. I don't necessarily
>understand _how_ that works, but I'll take their word
>for it :)
>
>My question is, doesn't that mean that it would be
>somehow possible to derive someone's private key from
>their public one, using some sort of inverse function?
>Presumably there must be checks in place to prevent
>that, but how do they work?
>
>Just curious
>Andrew
>
>
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