3 ms·
> XOR is not a great choice here. Consider that 2 copies of a row give the same result as 0 (or 4, 6, etc). That indeed is a major flaw. You have to use anothe
by Someone 3y ago
> XOR is not a great choice here. Consider that 2 copies of a row give the same result as 0 (or 4, 6, etc).
That indeed is a major flaw. You have to use another commutative operation that doesn’t destroy entropy. Addition seems a good choice to me.
> And even without multiple copies of rows, you can force any hash you'd like
I don’t see how that matters for this problem.
- sibrahim 3y agoIt depends on whether you are doing something security critical with the result. Maybe you have a trusted table hash but only a user-supplied version of the table. Before you use that data for security sensitive queries, you should verify it hasn't been modified. Basically, if you ever have to contend with a malicious adversary, things are more interesting as usual. If not, addition is likely fine (though 2^k copies of a row now leave the k lowest bits unchanged).