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Date: Tue, 11 Jun 2013 19:56:45 +1000
From: Michael Samuel <mik@...net.net>
To: john-users@...ts.openwall.com
Subject: Re: Extra functions/datatypes for external mode?

Ok, so I just made a mapping of the points in which the number changes -
not pretty, but accurate :)

Are functions completely off-limits in external mode (eg. even for use
within the same external generator)?


On 10 June 2013 09:12, Michael Samuel <mik@...net.net> wrote:

> On 10 June 2013 02:39, Solar Designer <solar@...nwall.com> wrote:
>
>> Can you post the relevant excerpt from your C code (along with the
>>  relevant variable declarations)?  Did the original password generator
>> use the "double" data type too?
>>
>> The original used the dot-net System.Random library, which expands the
> entropy out
> with this trick:
>
> int32_t Random_Sample(random_state_t* state);
>
> double Random_NextDouble(random_state_t* state)
> {
>         return ((double)Random_Sample(state)) * 4.6566128752457969E-10; /*
> Reciprocal of 2^31 */
> }
>
> int Random_NextInt(random_state_t* state, int maxValue)
> {
>         assert(maxValue >= 0);
>         return (int)(Random_NextDouble(state) * (double)maxValue);
> }
>
> I think that in your case it'd be best to go with emulating the one
>> conversion via "double" in 32-bit integer arithmetic in an external
>> mode, if having to implement that conversion is not easily avoidable.
>>
>
> I have code now that works well with john --stdin - so I guess I'm happy
> to leave it at that.  Also, since I'm only asking for random integers of
> sizes 4, 10, 26 and 32 - I could just make a table of answers.
>
>

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