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List:       cryptography
Subject:    Re: [Cryptography] [Crypto-practicum] Justify the sequence of operations in CTR mode.
From:       Bill Frantz <frantz () pwpconsult ! com>
Date:       2016-02-26 1:39:07
Message-ID: r470Ps-10113i-C0F5D7155F9E44B8A3B0A8F252B9B99C () Williams-MacBook-Pro ! local
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On 2/23/16 at 1:17 PM, leichter@lrw.com (Jerry Leichter) wrote:

>2.  We generally assume that a write to a disk block is 
>atomic:  It either completes successfully (replacing all the 
>old data with the new) or fails completely (leaving the old 
>data unchanged).  Unfortunately, this isn't true.  I can't give 
>a reference right now, but detailed studies of disk failure 
>modes show that all kinds of bizarre failures can and do occur.

The IBM 3830 disk controller and other similar controllers has a 
specified behavior when the the IBM channel (think DMA) did 
provide bytes fast enough.

The specified action was to fill the block on disk with the last 
byte received from the channel and then write a good error 
checking code. Why the didn't write a bad error checking code to 
indicate the write had failed is beyond me.

Cheers - Bill

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Bill Frantz        | Re: Hardware Management Modes: | Periwinkle
(408)356-8506      | If there's a mode, there's a   | 16345 
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www.pwpconsult.com | failure mode. - Jerry Leichter | Los Gatos, 
CA 95032

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