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Re: Business models

dulsi@identicalsoftware.com (Dennis Payne) writes:

> > How about a scheme with the license key being a small non-secret
> > key-id paired with a secret and sufficiently large cryptographic key.
> The only problem with that is that you must send them the file with
> the large cryptographic key when they purchase the game (or insert it
> in when they download the game).  This prevents a cdrom
> distribution.

That depends on how large "sufficiently large" is.  As the the data
communicated over the channel secured with the license key is not
really critical (a one-time session key), the important aspect of the
key would be that it should be hard to guess a passwd.  If you use a
128 bit key and have a very good random number generator, it should be
virtually impossible to guess a random passwd.  A 128 bit key can be
encoded nicely in 19 7-bit ascii characters, which could be printed on
cover label.  I (still) believe my scheme is feasible.

> I'm assuming burning cdrom individually isn't really feasible.

I don't believe so either.

> You could include a database of large cryptographic keys but then
> once again you need a relatively ungessable license keys.

It would make it possible for a cracker to get hand of a large number
of keys.  Not really very good.

> You could have it download the first time you play it but what
> happens if I uninstall it, get a new computer, or want to put it on
> my laptop as well.  If you allow it to be downloaded any number of
> times you are back to creating ungessable license keys.

I agree.  Something like that could easily get ugly and very user


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