assetseed cli app

.gitignore

@@ -21,6 +21,7 @@ dist/
 node_modules/
 client/cmd/dexc/dexc
 client/cmd/dexcctl/dexcctl
+client/cmd/assetseed/assetseed
 docs/examples/rpcclient/rpcclient
 wiki
 dex/testing/loadbot/loadbot

client/cmd/assetseed/main.go

@@ -0,0 +1,43 @@
+// This code is available on the terms of the project LICENSE.md file,
+// also available online at https://blueoakcouncil.org/license/1.0.0.
+
+package main
+
+import (
+	"encoding/hex"
+	"flag"
+	"fmt"
+	"os"
+
+	"decred.org/dcrdex/client/core"
+)
+
+func main() {
+	var appSeed string
+	flag.StringVar(&appSeed, "seed", "", "DEX client application seed (128 hexadecimal characters)")
+	var assetID uint
+	flag.UintVar(&assetID, "asset", 0, "Asset ID. BIP-0044 coin type (integer).\n"+
+		"See https://github.com/satoshilabs/slips/blob/master/slip-0044.md")
+	flag.Parse()
+
+	if appSeed == "" {
+		flag.Usage()
+		os.Exit(1)
+	}
+
+	appSeedB, err := hex.DecodeString(appSeed)
+	if err != nil {
+		fmt.Fprintf(os.Stderr, "bad app seed: %v\n", err)
+		os.Exit(1)
+	}
+
+	if len(appSeedB) != 64 {
+		fmt.Fprintf(os.Stderr, "app seed is %d bytes, expected 64\n", len(appSeedB))
+		os.Exit(1)
+	}
+
+	seed, _ := core.AssetSeedAndPass(uint32(assetID), appSeedB)
+	fmt.Printf("%x\n", seed)
+
+	os.Exit(0)
+}

client/core/core.go

@@ -1832,11 +1832,15 @@ func (c *Core) assetSeedAndPass(assetID uint32, crypter encrypt.Crypter) (seed,
 		return nil, nil, fmt.Errorf("app seed decryption error: %w", err)
 	}
 
-	seed, pass = assetSeedAndPass(assetID, appSeed)
+	seed, pass = AssetSeedAndPass(assetID, appSeed)
 	return seed, pass, nil
 }
 
-func assetSeedAndPass(assetID uint32, appSeed []byte) ([]byte, []byte) {
+// AssetSeedAndPass derives the wallet seed and password that would be used to
+// create a native wallet for a particular asset and application seed. Depending
+// on external wallet software and their key derivation paths, this seed may be
+// usable for accessing funds outside of DEX applications, e.g. btcwallet.
+func AssetSeedAndPass(assetID uint32, appSeed []byte) ([]byte, []byte) {
 	b := make([]byte, len(appSeed)+4)
 	copy(b, appSeed)
 	binary.BigEndian.PutUint32(b[len(appSeed):], assetID)

client/core/core_test.go

@@ -7287,7 +7287,7 @@ func TestCredentialHandling(t *testing.T) {
 	// Decred wallet"
 }
 
-func TestCore_assetSeedAndPass(t *testing.T) {
+func TestCoreAssetSeedAndPass(t *testing.T) {
 	// This test ensures the derived wallet seed and password are deterministic
 	// and depend on both asset ID and app seed.
 
@@ -7339,7 +7339,7 @@ func TestCore_assetSeedAndPass(t *testing.T) {
 	}
 	for _, tt := range tests {
 		t.Run(tt.name, func(t *testing.T) {
-			seed, pass := assetSeedAndPass(tt.assetID, tt.appSeed)
+			seed, pass := AssetSeedAndPass(tt.assetID, tt.appSeed)
 			if !bytes.Equal(pass, tt.wantPass) {
 				t.Errorf("pass not as expected, got %#v", pass)
 			}