[Hardware] Notes... The case for an open client

Dan Oetting dan_oetting at uswest.net
Mon Aug 16 23:39:51 EDT 2004


On Aug 16, 2004, at 8:09 PM, jbass at dmsd.com wrote:

> Elektron <elektron_rc5 at yahoo.ca> writes:
>> Neither have you given any evidence that hash is weak, or produces an
>> n-bit result with biased run lengths. After your table of run lengths,
>> you give this argument:
>
> No - because you started out with a tirade about why it was impossible,
> instead of simply asking why I might be considering this conjecture:
>
> RSA Key run lengths:
>
>   1  2  3  4  5  6  7  8
>  -- -- -- -- -- -- -- --
>  10  9  3  4  2  0  0  0        0x67b9e0ec4f20d95e;    //DES Test
>   9  6  2  2  1  0  0  0        0x43d26dd827;          //RC5-40 Test
>  10  4  3  2  1  0  0  1        0x510678042628;        //RC5-48 Test
>  20 12  4  0  0  0  0  0        0xda989a5ab31114;      //RC5-56 Test
>   7  9  5  1  4  0  0  0        0xf918c79c9f1be582;    //RC5-64 Test
>  13 10  2  3  1  1  0  0        0x3d986e6bf1be4bda;    //DES Challenge
>  15 10  3  3  0  0  0  0        0x9909C24C742B53;      //RC5-56 
> Challenge
>  13  7  5  3  2  0  0  0        0x39D0F454C17DDE63;    //RC5-64 
> Challenge
>  -- -- -- -- -- -- -- --
>  97 67 27 18 11  1  0  1
>
>
> Which for 453 or so bits, is biased, but not horribly so.

The next question a statistician will ask himself is wether this 
observed bias is statistically significant. Generally the result is 
significant if there is less than a 5% chance that the result was due 
to random fluctuations.

You don't need to be a math head to compute the significance. Just 
generate a large number of random samples just like the set above and 
count the number that have the same or greater bias.



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