Corrections: Maximum password template entropy

debiantriage's Avatar

debiantriage

26 Sep, 2017 02:02 PM

In this discussion we are told

....."Maximum" password template which has an entropy just shy of 124 bits [1]

and at [1] 9,223,372,036,854,775,807 is given as the as the result of the calculation. But

 echo 'l(9223372036854775807)/l(2)' | bc -l

is 63 bits of entropy. So, checking the calculation

echo 86^17*52*24*10+86^17*52*24*10 | bc

I get 19218445308363549398955938143178588160 and

echo 'l(19218445308363549398955938143178588160)/l(2)' | bc -l

gives 123.9 bits of entropy, which fits nicely with the claimed 124 bits of entropy for the Maximum Security password template.

The 9,223,372,036,854,775,807 figure is also quoted here. With it I cannot reproduce the time requirement of 17530003457999998976 years, assuming 30 million password guesses per second.

echo 9223372036854775807/30000000/3600/24/365 | bc = 9729 years

whereas

echo 19218445308363549398955938143178588160/30000000/3600/24/365 | bc = 2.03*10^22 years.

Am I being overly concerned that mpw is being undersold? :)

Regards,

Brian.

  1. Support Staff 1 Posted by Maarten Billemo... on 26 Sep, 2017 03:16 PM

    Maarten Billemont's Avatar

    You are correct, I've fixed the number. My printf overflowed in the calculation, causing a truncated result.

    Thanks.

  2. Maarten Billemont closed this discussion on 26 Sep, 2017 03:16 PM.

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