We need separate functions for checking Sprout and Sapling nullifiers,
because they are in separate domains and aren't guaranteed to be
collision-resistant (otherwise there is a possibility of a nullifier
collision, however remote, between Sprout and Sapling causing the spend
of one to prevent the spend of the other).
When diversified addresses are supported, iterating over
mapSaplingIncomingViewingKeys will be inefficient as the mapping will
be addresses->ivk (n:1).
Before Sapling activates, hashFinalSaplingRoot is 0x0, which is
not a valid anchor. After Sapling activates, the empty root value
of 0x3e49... is a valid anchor.
Add change indicator
This adds to the json returned when calling z_listreceivedbyaddress and z_listuspent an additional field entitiled 'change' which will be either true or false depending on whether or not the note was change from another transaction.
libzcash::PaymentAddress has been renamed to libzcash::SproutPaymentAddress,
and a new typedef boost::variant is now libzcash::PaymentAddress. Similarly
for ViewingKey and SpendingKey.
A new class InvalidEncoding is introduced as the default boost::variant
option for each address and key type; it is used during decoding instead
of boost::optional.
All address and key storage functions in the wallet have been modified to
refer specifically to the Sprout types, as they are used very precisely.
In most other cases, the more general type is leveraged as much as possible,
and we convert to the Sprout type when necessary. This will be subsequently
wrapped in, or replaced with, context-specific functions once Sapling
types are implemented.
Key encoding refactor
Includes code cherry-picked from the following upstream PRs:
- bitcoin/bitcoin#11372
- Only the first three commits (the fourth commit depends on #2390)
Part of #3058.
