Re: Generating session keys in RPG using HASH values

Tom, the hashing and/or "randomness" of the data is for security reasons,
not just to ensure uniqueness.  We're trying to generate a random key that
someone couldn't just edit with Notepad and resend to our server.  The
hashing I was asking about came from a paper I read that used a hashing
routine to generate pseudo-random numbers.  Actually Bryan Yates idea about
using the UUID api sounds really good and I'm in the process of trying it
right now.


----- Original Message -----
From: "Tom Jedrzejewicz @ San Pedro" <TJedrzejewicz@contessa.com>
To: <web400@midrange.com>
Sent: Thursday, January 16, 2003 2:54 PM
Subject: Re: [WEB400] Generating session keys in RPG using HASH values


> Why do the hashing?
>
> How about 12i number jjjhhmmssxxx
>       jjj = julian day
>       hhmmss = time
>       xxx = adjusted milliseconds
>
> I is guaranteed unique for a year, a duplicate is a virtual
> impossibility, and you don't have to screw around with figuring out
> API's etc.
>
> Take care.
>
> >>> mskvarenina@usa.net 01/16/03 11:02AM >>>
> Tom, that was my first idea.  I cooked up an algorithm that took the
> timestamp, including the milliseconds and performed a bunch of
> mathematics
> to it but as you can see below, patterns became obvious.  The columns
> were
> as follows:  Milliseconds (note we don't get the full 6 digits in
> RPG),
> adjusted milliseconds, second, minute, hour, minute, calculated
> number,
> substring of calculated number.
>
>  692000   692   04   17   10   16   000172757734260   757734
>  693000   693   04   17   10   16   000173007384165   007384
>  694000   694   04   17   10   16   000173257034070   257034
>  695000   695   04   17   10   16   000173506683975   506683
>  696000   696   04   17   10   16   000173756333880   756333
>  697000   697   04   17   10   16   000174005983785   005983
>  698000   698   04   17   10   16   000174255633690   255633
>  699000   699   04   17   10   16   000174505283595   505283
>  700000   700   04   17   10   16   000174754933500   754933
>  701000   701   04   17   10   16   000175004583405   004583
>  702000   702   04   17   10   16   000175254233310   254233
>  703000   703   04   17   10   16   000175503883215   503883
>  704000   704   04   17   10   16   000175753533120   753533
>  705000   705   04   17   10   16   000176003183025   003183
>  706000   706   04   17   10   16   000176252832930   252832
>
>
>
> ----- Original Message -----
> From: "Tom Jedrzejewicz @ San Pedro" <TJedrzejewicz@contessa.com>
> To: <web400@midrange.com>
> Sent: Thursday, January 16, 2003 1:23 PM
> Subject: Re: [WEB400] Generating session keys in RPG using HASH values
>
>
> > How about getting the current system time out to the millisecond?
> > It isn't random, but it will be unique.
> >
> > >>> mskvarenina@usa.net 01/16/03 08:59AM >>>
> > I need to generate a pseudo-random character string to be used as a
> > session key in my browser applications.  Has anyone used a hashing
> > method in RPG to generate a pseudo-random number and if so, could
> you
> > please post it.
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> THIS MESSAGE IS INTENDED ONLY FOR THE USE OF THE INDIVIDUAL OR ENTITY TO
WHICH IT IS ADDRESSED AND MAY CONTAIN INFORMATION THAT IS PRIVILEGED,
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of this message is not the intended recipient, or the employee or agent
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