Re: [CISSP-D] Re: Work factor of Birthday attacks

--- "Rob, grandpa of Ryan, Trevor, Devon & Hannah"
<rslade@computercrime.org> wrote:

> Thus, (roughly) 20 people's 
> birthdays will generate a match out of the (roughly)
> 400 days in a year.  (OK, I 
> *said* this was extremely simplified: for birthdays
> the actual numbers are 23 and 
> 365.)

Strictly speaking, you have to say that "on average"
you will get a collision (aka match) with 20 birthdays
(note, you could've picked a group where all 20 have
different birthdays, or all 20 have the same
birthday).  Or, you can say that statistically, you
can expect to get a collision after asking 20 people
for their birthdays.  This tends to be more accurate
with very large values, where collisions are extremely
unlikely.

Here is the Wiki page on the Birthday Paradox:
  http://en.wikipedia.org/wiki/Birthday_attack

Regards,

- Larry D. Weiner


 
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