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Article #10Re: Gathering entropy for PRNGs on MVS
From: Duke Arber
Date: Mon, 10 Mar 2003 17:19
Date: Mon, 10 Mar 2003 17:19
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2299 bytes
> > How accurately can you measure time? > > Read the time and date. Reschedule so the operating system > runs and read the time when you are reactivated. The > entropy comes from the run time of the other programs and > the date. You may be able to play games with the disks and > operator reply times. > > Andrew Swallow > The hardware clock resolution depends on the actual hardware model. The Time-Of-Day (TOD) API returns a microsecond resolution. I think it's "safe to say" that most of the models produced in the last 5 years have <=20 microsecond resolution. Others in the IBM-MAIN newsgroup may be able to fill in the details. Basically, use the current O/S activity rate as a basis for entropy. Hand off control back to the O/S and depending on its activity, it will hand control back in some period of time. During an IPL, there is a lot of activity. During other periods of the day, there may be very little. Would this hold up during periods of low activity?
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X-Google-Language: ENGLISH,ASCII-7-bit X-Google-Thread: fd4af,4336d2c2bccbde14 X-Google-Attributes: gidfd4af,public X-Google-Thread: fb57f,4336d2c2bccbde14 X-Google-Attributes: gidfb57f,public X-Google-Thread: fed83,4336d2c2bccbde14 X-Google-Attributes: gidfed83,public X-Google-ArrivalTime: 2003-03-10 09:19:49 PST Path: arc1-ca.pugleaf.net!archiver1.google.com!news1.google.com!newsfeed.stanford.edu!newsfeed.berkeley.edu!ucberkeley!cyclone-sf.pbi.net!151.164.30.35!cyclone.swbell.net!newsfeed1.easynews.com!easynews.com!easynews!newsfeed1.earthlink.net!newsfeed.earthlink.net!stamper.news.pas.earthlink.net!stamper.news.atl.earthlink.net!harp.news.atl.earthlink.net!not-for-mail From: "Duke Arber" <duke_arber@yahoo.com> Newsgroups: sci.crypt.random-numbers,bit.listserv.ibm-main,sci.crypt Subject: Re: Gathering entropy for PRNGs on MVS Date: Mon, 10 Mar 2003 12:19:40 -0500 Organization: MindSpring Enterprises Lines: 25 Message-ID: <b4ihfk$4oh$1@slb0.atl.mindspring.net> References: <b4ieak$2qn$1@slb9.atl.mindspring.net> <b4if1a$jte$1@helle.btinternet.com> NNTP-Posting-Host: 3f.b7.a1.10 X-Server-Date: 10 Mar 2003 17:19:48 GMT X-Priority: 3 X-MSMail-Priority: Normal X-Newsreader: Microsoft Outlook Express 5.50.4920.2300 X-MimeOLE: Produced By Microsoft MimeOLE V5.50.4920.2300