eth/client/core: Derive account from app seed

asset.Driver is now updated with a Create function, which is
used to initialize a seeded wallet. The wallet seed is derived
from the app seed using blake256(appSeed| asssetID) and is passed
to the create function. The private key for the ETH wallet is
derived from this seed using the following BIP32 derivation path:
m/44'/60'/0'/0/0.

client/asset/bch/bch.go

@@ -98,11 +98,15 @@ func init() {
 // Driver implements asset.Driver.
 type Driver struct{}
 
-// Setup creates the BCH exchange wallet. Start the wallet with its Run method.
-func (d *Driver) Setup(cfg *asset.WalletConfig, logger dex.Logger, network dex.Network) (asset.Wallet, error) {
+// Open opens the BCH exchange wallet. Start the wallet with its Run method.
+func (d *Driver) Open(cfg *asset.WalletConfig, logger dex.Logger, network dex.Network) (asset.Wallet, error) {
 	return NewWallet(cfg, logger, network)
 }
 
+func (d *Driver) Create(params *asset.CreateWalletParams) error {
+	return fmt.Errorf("no creatable wallet types")
+}
+
 // DecodeCoinID creates a human-readable representation of a coin ID for
 // Bitcoin Cash.
 func (d *Driver) DecodeCoinID(coinID []byte) (string, error) {

client/asset/btc/btc.go

@@ -330,11 +330,15 @@ func (r *swapReceipt) SignedRefund() dex.Bytes {
 // Driver implements asset.Driver.
 type Driver struct{}
 
-// Setup creates the BTC exchange wallet. Start the wallet with its Run method.
-func (d *Driver) Setup(cfg *asset.WalletConfig, logger dex.Logger, network dex.Network) (asset.Wallet, error) {
+// Open opens the BTC exchange wallet. Start the wallet with its Run method.
+func (d *Driver) Open(cfg *asset.WalletConfig, logger dex.Logger, network dex.Network) (asset.Wallet, error) {
 	return NewWallet(cfg, logger, network)
 }
 
+func (d *Driver) Create(*asset.CreateWalletParams) error {
+	return fmt.Errorf("no creatable wallet types")
+}
+
 // DecodeCoinID creates a human-readable representation of a coin ID for
 // Bitcoin.
 func (d *Driver) DecodeCoinID(coinID []byte) (string, error) {

client/asset/dcr/dcr.go

@@ -378,11 +378,15 @@ type fundingCoin struct {
 // Driver implements asset.Driver.
 type Driver struct{}
 
-// Setup creates the DCR exchange wallet. Start the wallet with its Run method.
-func (d *Driver) Setup(cfg *asset.WalletConfig, logger dex.Logger, network dex.Network) (asset.Wallet, error) {
+// Open opens the DCR exchange wallet. Start the wallet with its Run method.
+func (d *Driver) Open(cfg *asset.WalletConfig, logger dex.Logger, network dex.Network) (asset.Wallet, error) {
 	return NewWallet(cfg, logger, network)
 }
 
+func (d *Driver) Create(*asset.CreateWalletParams) error {
+	return fmt.Errorf("no creatable wallet types")
+}
+
 // DecodeCoinID creates a human-readable representation of a coin ID for Decred.
 func (d *Driver) DecodeCoinID(coinID []byte) (string, error) {
 	txid, vout, err := decodeCoinID(coinID)

client/asset/driver.go

@@ -15,13 +15,35 @@ var (
 	drivers    = make(map[uint32]Driver)
 )
 
+// CreateWalletParams are the parameters for internal wallet creation. The
+// Settings provided should be the same wallet configuration settings passed to
+// Open.
+type CreateWalletParams struct {
+	Seed     []byte
+	Pass     []byte
+	Settings map[string]string
+	DataDir  string
+	Net      dex.Network
+}
+
 // Driver is the interface required of all exchange wallets.
 type Driver interface {
-	Setup(*WalletConfig, dex.Logger, dex.Network) (Wallet, error)
+	Create(*CreateWalletParams) error
+	Open(*WalletConfig, dex.Logger, dex.Network) (Wallet, error)
 	DecodeCoinID(coinID []byte) (string, error)
 	Info() *WalletInfo
 }
 
+func withDriver(assetID uint32, f func(Driver) error) error {
+	driversMtx.Lock()
+	defer driversMtx.Unlock()
+	drv, ok := drivers[assetID]
+	if !ok {
+		return fmt.Errorf("asset: unknown driver asset %d", assetID)
+	}
+	return f(drv)
+}
+
 // Register should be called by the init function of an asset's package.
 func Register(assetID uint32, driver Driver) {
 	driversMtx.Lock()
@@ -39,27 +61,29 @@ func Register(assetID uint32, driver Driver) {
 	drivers[assetID] = driver
 }
 
-// Setup sets up the asset, returning the exchange wallet.
-func Setup(assetID uint32, cfg *WalletConfig, logger dex.Logger, network dex.Network) (Wallet, error) {
-	driversMtx.Lock()
-	drv, ok := drivers[assetID]
-	driversMtx.Unlock()
-	if !ok {
-		return nil, fmt.Errorf("asset: unknown asset driver %d", assetID)
-	}
-	return drv.Setup(cfg, logger, network)
+// CreateWallet creates a new wallet. This method should only be used once to create a
+// seeded wallet, after which OpenWallet should be used to load and access the wallet.
+func CreateWallet(assetID uint32, seedParams *CreateWalletParams) error {
+	return withDriver(assetID, func(drv Driver) error {
+		return drv.Create(seedParams)
+	})
+}
+
+// OpenWallet sets up the asset, returning the exchange wallet.
+func OpenWallet(assetID uint32, cfg *WalletConfig, logger dex.Logger, net dex.Network) (w Wallet, err error) {
+	return w, withDriver(assetID, func(drv Driver) error {
+		w, err = drv.Open(cfg, logger, net)
+		return err
+	})
 }
 
 // DecodeCoinID creates a human-readable representation of a coin ID for a named
 // asset with a corresponding driver registered with this package.
-func DecodeCoinID(assetID uint32, coinID []byte) (string, error) {
-	driversMtx.Lock()
-	drv, ok := drivers[assetID]
-	driversMtx.Unlock()
-	if !ok {
-		return "", fmt.Errorf("asset: unknown asset driver %d", assetID)
-	}
-	return drv.DecodeCoinID(coinID)
+func DecodeCoinID(assetID uint32, coinID []byte) (cid string, err error) {
+	return cid, withDriver(assetID, func(drv Driver) error {
+		cid, err = drv.DecodeCoinID(coinID)
+		return err
+	})
 }
 
 // A registered asset is information about a supported asset.