struct variable initialized with void.

[John Colvin via Digitalmars-d-learn]

On Tuesday, 31 March 2015 at 16:24:02 UTC, John Colvin wrote:
> On Tuesday, 31 March 2015 at 16:10:07 UTC, Adam D. Ruppe wrote:
>> On Tuesday, 31 March 2015 at 15:59:53 UTC, John Colvin wrote:
>>> Like almost never? I can't think of any reason to ever do 
>>> that.
>>
>> I mentioned it because of this story:
>>
>> https://www.schneier.com/blog/archives/2008/05/random_number_b.html
>>
>> I'm sure there's better ways to do it, but since a similar 
>> technique was used in a high profile product, I thought I'd 
>> mention it as a possible use.
>>
>> though I'd recommend against trying this at home for anything 
>> serious since there's better sources of more random 
>> randomness...
>
> In general, I can't think of a worse way of choosing a seed 
> other than a fixed value*. It's actually quite interesting 
> thinking of all the ways it's bad :)

More fun than I thought:

Depending on the OS and toolchain, you might be looking at 
anything in the current process (at best).

That seed might be directly drawn from user data: an attacker 
could conceivably now choose your seed.

The seed might contain sensitive data: an attacker who can 
measure the output of the PRNG might be able to work backwards to 
find the seed, exposing the data.

You might always seed 0, or some other fixed value, or something 
almost always fixed depending on the program state: heavily 
biased towards certain values, bad for randomness.

Based on observable state, an observer could conceivably infer or 
predict the value of the seed and hence predict future values 
from the PRNG.

and so on...