Flush witness data to disk only when it's consistent
Closes#4301. Running this PR's code will not repair a data directory that has been affected by this problem; that requires starting zcashd with the `-rescan` or `-reindex` options.
This makes the test more deterministic. When the nodes are split, and
partition B (node 1) mines a joinsplit transaction, that block only
sometimes appears on the blockchain after the nodes are all reconnected.
ZIP212 implementation
Closes#4557.
(description by @ebfull, taken from #4575)
* The `SaplingNote` structure has a new enum called `zip212Enabled`. This
member is private and reflects whether the note was or is being created
using the derivation method of ZIP 212 (i.e., `BeforeZip212` or `AfterZip212`).
* The `SaplingNotePlaintext` structure has a new unsigned char member
`leadbyte`. This member is private and contains the leading byte of the
plaintext (e.g. `0x01`, `0x02`).
* The serialization of `SaplingNotePlaintext` sets `zip212Enabled` to
`BeforeZip212` iff the serialized note plaintext version is not `0x01`.
* The `r`/`rcm` fields have been removed and replaced with a private field
`rseed`. `SaplingNote` and `SaplingNotePlaintext` now have a helper method
`rcm()` which returns the `rcm` either by deriving it with `rseed`
(if `zip212Enabled` is `AfterZip212`) or returning `rseed` by interpreting
`rseed` as `rcm`.
* All the methods of obtaining a `SaplingNote` account for these changes:
- The `SaplingNote` constructor that is used by e.g. the transaction builder,
and internally samples random `rcm`, now takes a `zip212Enabled` argument
to decide whether to sample `rcm` the "old" way or the "new" way.
- The bare constructor for `SaplingNote` is removed.
- The other constructor which takes the raw contents of the note is only used
in tests or in `Note.cpp`, but now also takes a `zip212Enabled` argument.
- The other way of obtaining a note, by calling `SaplingNotePlaintext::note()`,
has been adjusted.
* The `SaplingNotePlaintext` class now has an `generate_or_derive_esk()` method
that either samples a random `esk` or derives it using the local `rseed`
depending on the value of `leadbyte`.
* The encryption routine is modified to consult `generate_or_derive_esk()` and
provide it to the note encryption object.
* The note encryption objects now take an optional `esk` as input and otherwise
sample a random `esk` internally. This API functionality is preserved to allow
for testing.
* The `SaplingNotePlaintext` decryption routines are modified:
- The out and enc decryption routines now check that `epk` is consistent with
the derived `esk`.
- The out decryption routine for plaintexts also checks that `esk` is
consistent with what is derived by the note.
* The miner and transaction builder consult the activation of Canopy when
creating `SaplingNote`s.
* The consensus rules are modified so that shielded outputs (miner rewards)
must have `v2` note plaintexts after Canopy has activated.
This fixes wallet_anchorfork.py CI failure, but a separate PR
will restore flushing witness data on shutdown while also
fixing DecrementNoteWitnesses() to not assert when
nd->witnessHeight < indexHeight, which can happen when the
node reorgs upon restart (which this test causes to happen).
It needs to be closer to the root of our dependency tree, so that it can
depend on the transaction format. The libzcash compilation unit is
further from the dependency tree root than the transaction format.
We don't support making pre-Sapling JoinSplit proofs, and we load the
parameters for post-Sapling JoinSplit proofs at proving time, so there
is no need for a global ZCJoinSplit to be passed through the APIs.
We only relied on success being 0 and our code was otherwise agnostic to the
actual return code in the event of failed signature verification, but this
change keeps the API consistent.
[ZIP 211] Disabling Addition of New Value to the Sprout Value Pool
Disables Sprout outputs after NU4 by checking for nonzero `vpub_old` in transactions after NU4 activation height.
Adds gtests to check expected behaviour before and after NU4 activation height.
edit:
Also modifies `z_` methods in `rpcwallet`, and adds a matching RPC test.
Implements [ZIP 211](https://zips.z.cash/zip-0211), closes#4479
Daira Hopwood
Homu
Kris Nuttycombe
Kris Nuttycombe
Larry Ruane
therealyingtong
Jack Grigg
Sean Bowe