[GNC-dev] Normalizing live data

John Ralls jralls at ceridwen.us
Sat Feb 2 13:00:12 EST 2019

> On Feb 2, 2019, at 9:44 AM, Hendrik Boom <hendrik at topoi.pooq.com> wrote:
> On Sat, Feb 02, 2019 at 04:30:30PM +0100, Geert Janssens wrote:
>> Op zaterdag 2 februari 2019 14:31:43 CET schreef Hendrik Boom:
>>>> On 2/1/19 5:36 AM, Wm via gnucash-devel wrote:
>>>>> [2] as long as the transaction stream balances the actual numbers
>>>>> don't matter (their will be occasions where the numbers are important
>>>>> but these tend to be number extremes related to commodities rather
>>>>> than anyone using gnc to do a Mr Putin vs Mr Trump sports bet).? In
>>>>> most cases multiplying any matching numbers by the same semi-random
>>>>> should produce a good file for examination so long as it is done
>>>>> consistently [4]
>>> If the numbers in the file are integers times some account or
>>> currency-dependent unit, then just clculationg the greatest common
>>> divisor of all the obfuscated numbers will give a good guess as to the
>>> semirandom multiplier.
>> Do you think that still is possible if a different random number was used for 
>> each transaction ? (That's how I understood Wm's suggestion)
>> Each transaction will have it's own random number. So for transaction A all 
>> splits may have been multiplied with 450, for Transaction B all numbers may 
>> have been multiplied by 500. 
> That might work.  That way eash transaction balances, but the account 
> balances will be nonsense.
> Still, by finding the gcd you can still produce a lower bound on the 
> transaction values.  And if you, say, split off sales tax into a separate 
> split your lower bound will oftern be the actual value.
> And it's likely that one could also identify income and expense accounts as 
> such by the pattern of debits vs credits.

So maybe we should just forget it and continue the practice of asking users to send their account files directly to a developer with the promise of confidentiality if they're unable to reproduce the bug in a test file. No one has demurred yet.

John Ralls

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