a6d5bb75 wallet2: refer to triangular distribution for recent zone in comment (moneromooo-monero)
ac1aba90 wallet2: bias fake outs more towards recent outputs (moneromooo-monero)
It was wrongly refering to equiprobable distribution, which I think
I'd originally done, but forgot to update the comment after changing
to triangular
Reported by smooth on IRC
Two recent papers quantified the real usage bias for the
real output in a ring being the true one, and shows that
the current biasing is much too weak.
While we wait for a better solution, we increase the ratio
of recent-to-total fake outputs, as well as decrease the
time window for recent outputs, so that half the fake outs
are selected within the last 1.8 day. Value plucked from
figure 10, page 11 of An Empirical Analysis of Linkability
in the Monero Blockchain, 2017, Miller et al.
This is also arbitrary, of course, but serves as a stopgap
till a better selection algorithm is chosen.
If using a large input and many destinations, the code would
generate as many outputs as it could using that input, even if
it would bring the resulting tx above the max tx size.
With the change from the original transfer method to the new
algorithm, payments to the same destination were merged. It
seemed like a good idea, optimizing space. However, it is a
useful tool for people who want to split large outputs into
several smaller ones (ie, service providers making frequent
payments, and who do not like a large chunk of their balance
being locked for 10 blocks after each payment).
Default to off, which is a change from the previous behavior.
When a single input is enough to satisfy a transfer, the code would
previously try to add a second input, to match the "canonical" makeup
of a transaction with two inputs and two outputs. This would cause
wallets to slowly merge outputs till all the monero ends up in a
single output, which causes trouble when making two transactions
one after the other, since change is locked for 10 blocks, and an
increasing portion of the remaining balance would end up locked on
each transaction.
There are two new settings (min-output-count and min-output-value)
which can control when to stop adding such unneeded second outputs.
The idea is that small "dust" outputs will still get added, but
larger ones will not.
Enable with, eg:
set min-output-count 10
set min-output-value 30
to avoid using an unneeded second output of 30 monero or more, if
there would be less than 10 such outputs left.
This does not invalidate any other reason why such outputs would
be used (ie, when they're really needed to satisfy a transfer, or
when randomly picked in the normal course of selection). This may
be improved in the future.
Asking for a full histogram from a remote node (since it's
untrusted) is pretty slow, and spams the remote node, so
we replace it by only adding a second input if we have rct
ones, which are for all intents and purposes always mixable.
Minimum mixin 4 and enforced ringct is moved from v5 to v6.
v5 is now used for an increased minimum block size (from 60000
to 300000) to cater for larger typical/minimum transaction size.
The fee algorithm is also changed to decrease the base per kB
fee, and add a cheap tier for those transactions which we do
not care if they get delayed (or even included in a block).
This reverts commit d47dac9a88.
Callers actually expect the key to be payment id, so this
needs a lot more changes (like storing payment ids in the
structure, and possibly also to other existing structures
which do the same thing).
A relatedness check was meant to be done in the case of adding
an extra output if just one was enough. This was mistakenly
added to the "preferred output" case.
