Implement secp256k1 and secp256r1 recover interops, closes#1003.
Note:
We have to implement Koblitz-related math to recover keys properly
with Neo.Cryptography.Secp256k1Recover interop as far as standard
go elliptic package supports short-form Weierstrass curve with a=-3
only (see https://github.com/golang/go/issues/26776 for details).
However, it's not the best choise to have a lot of such math in our
project, so it would be better to use ready-made solution for
Koblitz-related cryptography.
Because trie size is rather big, it can't be stored in memory.
Thus some form of caching should also be implemented. To avoid
marshaling/unmarshaling of items which are close to root and are used
very frequenly we can save them across the persists.
This commit implements pruning items at the specified depth,
replacing them by hash nodes.
There is nothing wrong with iterators being implemented in other parts
of code (e.g. Storage.Find). In this case type assertions can
prevent bugs at compile-time.
Reproduce behavior of the reference realization:
- if item was Put in cache after it was encountered during
Storage.Find, it must appear twice
- checking if item is in cache must be performed in real-time
during `Iterator.Next()`
bafdb916a0 change was wrong (probably brought
from neo-vm 3.0 at the state at which it existed back then), neo-vm 2.x
doesn't allow PICKITEM for arbitrary types.
The order in which storage.Find items are returns depends on what items
were processed in previous transactions of the same block.
The easiest way to implement this sort of caching is to cache operations
with storage, flushing the only in `Persist()`.
It's useless. Even though there is Neo.Transaction.GetUnspentCoins syscall
that can be used, its return type is an interop structure that's not accepted
by any other syscall, so you can't really do anything with it. And there is no
such interface for the .net Framework.
Previously we could generate dynamic appcall with a kludge of
AppCall([]byte{/* 20 zeroes */, realScriptHash, args...)
Now there is a separate function for this.
This syscall should only work for contracts created by current transaction and
that is what is supposed to be checked here. Do so by looking at the
differences between ic.dao and original lower DAO.
