When RingCT is enabled, outputs from coinbase transactions
are created as a single output, and stored as RingCT output,
with a fake mask. Their amount is not hidden on the blockchain
itself, but they are then able to be used as fake inputs in
a RingCT ring. Since the output amounts are hidden, their
"dustiness" is not an obstacle anymore to mixing, and this
makes the coinbase transactions a lot smaller, as well as
helping the TXO set to grow more slowly.
Also add a new "Null" type of rct signature, which decreases
the size required when no signatures are to be stored, as
in a coinbase tx.
This allows the key to be not the same for two outputs sent to
the same address (eg, if you pay yourself, and also get change
back). Also remove the key amounts lists and return parameters
since we don't actually generate random ones, so we don't need
to save them as we can recalculate them when needed if we have
the correct keys.
This plugs a privacy leak, where the wallet tells the daemon
which transactions contain outputs for the wallet by asking
for additional information for that particular transaction.
As a nice bonus, this actually makes refresh slightly faster.
With RCT, we allow 0 size outputs, to try and encourage txes
with two inputs and two outputs. Consolidation would then
have two non zero inputs, one zero output, and one larger
output.
Before the normal selection, we attempt to find either one or two
suitable outputs to use as inputs to the rct tx. The intent is that
most rct txes will have one or two inputs, and we want all to look
the same if possible.
When two outputs are needed, we try to find a pair which are not
related (ie, by being from the same or similar block height).
The "transfer" simplewallet command is renamed to "transfer_original".
"transfer_new" is renamed "transfer", "transfer_rct" is removed,
and the new "transfer" now selects rct or non rct transactions
based on the current block height.
The mixRing (output keys and commitments) and II fields (key images)
can be reconstructed from vin data.
This saves some modest amount of space in the tx.
If the blockchain gets reorganized, all outputs spent in the part
of the blockchain that's blown away need to be reset to unspent
(they may end up spent again on the blocks that replace the blocks
that are removed, however).
This plugs a privacy leak from the wallet to the daemon,
as the daemon could previously see what input is included
as a transaction input, which the daemon hadn't previously
supplied. Now, the wallet requests a particular set of
outputs, including the real one.
This can result in transactions that can't be accepted if
the wallet happens to select too many outputs with non standard
unlock times. The daemon could know this and select another
output, but the wallet is blind to it. It's currently very
unlikely since I don't think anything uses non default
unlock times. The wallet requests more outputs than necessary
so it can use spares if any of the returns outputs are still
locked. If there are not enough spares to reach the desired
mixin, the transaction will fail.
This constrains the number of instances of any amount
to the unlocked ones (as defined by the default unlock time
setting: outputs with non default unlock time are not
considered, so may be counted as unlocked even if they are
not actually unlocked).
They are used to export a signed set of key images from a wallet
with a private spend key, so an auditor with the matching view key
may see which of those are spent, and which are not.
Signing is done using the spend key, since the view key may
be shared. This could be extended later, to let the user choose
which key (even a per tx key).
simplewallet's sign/verify API uses a file. The RPC uses a
string (simplewallet can't easily do strings since commands
receive a tokenized set of arguments).
