[ale] little math

[Scott Castaline]

On 02/11/2010 10:05 AM, Geoffrey wrote:
> Boris Borisov wrote:
>>   Why you just not create small file ( 2 MB ) with random data and dd it
>> to the disk. dd ~/random.file>  /dev/hda.. Never tried but won't call
>> CPU to calculate every random number. Must be random enough.
>
> The randomness of such a solution is, a, not random?  You'd simply be
> repeating that same data, hence not random.  Which returns me to my
> original question, why is random data necessary?  Why not just write nulls?
>
>>
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>
Because I believe all you're getting is EOF. So you'd be getting, in my 
case, 1TB of EOFs. Not much randomness. It's my understanding that by 
filling the device with random data when you create the encrypted volume 
someone trying to crack it would have trouble "seeing where the valid 
data starts and ends. I think of it as an old school chalk board that 
gets heavily used but never washed. Eventually it's hard to read the 
written stuff because of all the remnants of stuff written on it in the 
past and erased.