This adds a new function, ExtendActiveAddresses, to extend the number
of active addresses, generated by the address chain, by any arbitrary
positive number. This will be used for recovering wallet addresses
from a wallet backup, as well as getting the next as many addresses as
required to keep a watching wallet in sync with an original wallet
with the private keys, or sync an original wallet with new addresses
generated by the watching wallet.
This change introduces a new function to export a wallet in memory to
a watching wallet. Watching wallets allow to watch for balance
changes and transactions to wallet addresses while only storing the
public parts of a wallet (no private keys). New addresses created by
the watching wallet will use pubkey address chaining and will allow to
receive funds to an indefinite number of new addresses, and create the
private keys for said addresses from the non-watching wallet later.
The actual exporting of a watching wallet to a file (triggered by an
RPC request) is not yet implemented.
While here, fix an issue found by new test code for the chained
address code which incorrectly set the starting index of addresses in
the chain needing private keys to be created.
This change uses the ChainedPubKey function to create addresses from
the previous address's public key and the wallet chaincode, without
the need for the private key, if the keypool has been depleted and the
wallet is locked. This is done since the next chained private key is
unsolvable without a locked wallet.
If a wallet contains any of these chained addresses with missing
private keys, the private keys are created during the next wallet
unlock, using ChainedPrivKey.
This change adds a function to generate the next public key of the
address chain from the previous public key and chaincode, without
needing the previous address's private key. This will be used to
allow generating new addresses with an unlocked wallet, where the
private keys are created on the next unlock.
Tests have been added to verify that the chained private and private
keys match each other (using both chaining functions) as well as an
expected value in the test case. ECDSA signature creation and
verifiction is also performed using the generated keypairs to verify
the next keypair is valid.
Wallets that include compressed pubkeys are no longer compatible with
armory, however, imported wallets from armory (using uncompressed
pubkeys) are still valid.
When a wallet is opened, a rescan request will be sent to btcd with
all active addresses from the wallet, to rescan from the last synced
block (now saved to the wallet file) and the current best block.
As multi-account support is further explored, rescan requests should
be batched together to send a single request for all addresses from
all wallets.
This change introduces several changes to the wallet, tx, and utxo
files. Wallet files are still compatible, however, a rescan will try
to start at the genesis block since no correct "last synced to" or
"created at block X" was saved. The tx and utxo files, however, are
not compatible and should be deleted (or an error will occur on read).
If any errors occur opening the utxo file, a rescan will start
beginning at the creation block saved in the wallet.
