From:	Damian Yerrick <MYNAMEISd_yerrick AT hotmail DOT comNO2CANNEDHAM>
Newsgroups:	comp.os.msdos.programmer,comp.os.msdos.djgpp
Subject:	Re: Uptime and entropy in DOS
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Date:	Sat, 12 Feb 2000 03:50:09 GMT
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On Fri, 11 Feb 2000 13:58:07 -0500, "Campbell, Rolf [SKY:1U32:EXCH]"
<moscoop AT americasm01 DOT nt DOT com> wrote:

>Link Hochnadel wrote:
>
>> "Campbell, Rolf [SKY:1U32:EXCH]" wrote:
>> >
>> > Damian Yerrick wrote:
>> >
>> > > Is it possible to get the uptime of a DOS system?  I need more entropy
>> > > than the 32 bits I get from time(NULL) to initialize a pseudorandom
>> > > number generator.  Is there a predictable way to get at least 64 bits
>> > > of entropy?
>> Flip the bits end-to-end, then multiply both values to get 64 bits.
>
>    That will only be 32-bit's of entropy in a 64-bit container.  It would be
>just as effective to assign the upper 32-bits some constant (like
>0xdeadbeef).

Which is a famous graphics library author's speedh AT ck password.

Anyway, how do I read these lower 32 bits of entropy? And what about
486s that lack the instruction? And what about portability? (I am
isolating and minimizing code that relies on a specific architecture.)

Are there other sources of entropy?
1. lower 16 bits of unix datetime
2. lower 32 bits of CPU uptime (Pentiums only)
3. __________________________________

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