chaincfg: Add RegisterHDKeyID func to populate HD key ID pairs

chaincfg/params.go

@@ -588,6 +588,10 @@ var (
 	// is intended to identify the network for a hierarchical deterministic
 	// private extended key is not registered.
 	ErrUnknownHDKeyID = errors.New("unknown hd private extended key bytes")
+
+	// ErrInvalidHDKeyID describes an error where the provided hierarchical
+	// deterministic version bytes, or hd key id, is malformed.
+	ErrInvalidHDKeyID = errors.New("invalid hd extended key version bytes")
 )
 
 var (
@@ -619,7 +623,11 @@ func Register(params *Params) error {
 	registeredNets[params.Net] = struct{}{}
 	pubKeyHashAddrIDs[params.PubKeyHashAddrID] = struct{}{}
 	scriptHashAddrIDs[params.ScriptHashAddrID] = struct{}{}
-	hdPrivToPubKeyIDs[params.HDPrivateKeyID] = params.HDPublicKeyID[:]
+
+	err := RegisterHDKeyID(params.HDPublicKeyID[:], params.HDPrivateKeyID[:])
+	if err != nil {
+		return err
+	}
 
 	// A valid Bech32 encoded segwit address always has as prefix the
 	// human-readable part for the given net followed by '1'.
@@ -666,6 +674,29 @@ func IsBech32SegwitPrefix(prefix string) bool {
 	return ok
 }
 
+// RegisterHDKeyID registers a public and private hierarchical deterministic
+// extended key ID pair.
+//
+// Non-standard HD version bytes, such as the ones documented in SLIP-0132,
+// should be registered using this method for library packages to lookup key
+// IDs (aka HD version bytes). When the provided key IDs are invalid, the
+// ErrInvalidHDKeyID error will be returned.
+//
+// Reference:
+//   SLIP-0132 : Registered HD version bytes for BIP-0032
+//   https://github.com/satoshilabs/slips/blob/master/slip-0132.md
+func RegisterHDKeyID(hdPublicKeyID []byte, hdPrivateKeyID []byte) error {
+	if len(hdPublicKeyID) != 4 || len(hdPrivateKeyID) != 4 {
+		return ErrInvalidHDKeyID
+	}
+
+	var keyID [4]byte
+	copy(keyID[:], hdPrivateKeyID)
+	hdPrivToPubKeyIDs[keyID] = hdPublicKeyID
+
+	return nil
+}
+
 // HDPrivateKeyToPublicKeyID accepts a private hierarchical deterministic
 // extended key id and returns the associated public key id.  When the provided
 // id is not registered, the ErrUnknownHDKeyID error will be returned.

chaincfg/params_test.go

@@ -4,7 +4,10 @@
 
 package chaincfg
 
-import "testing"
+import (
+	"bytes"
+	"testing"
+)
 
 // TestInvalidHashStr ensures the newShaHashFromStr function panics when used to
 // with an invalid hash string.
@@ -33,3 +36,51 @@ func TestMustRegisterPanic(t *testing.T) {
 	// Intentionally try to register duplicate params to force a panic.
 	mustRegister(&MainNetParams)
 }
+
+func TestRegisterHDKeyID(t *testing.T) {
+	t.Parallel()
+
+	// Ref: https://github.com/satoshilabs/slips/blob/master/slip-0132.md
+	hdKeyIDZprv := []byte{0x02, 0xaa, 0x7a, 0x99}
+	hdKeyIDZpub := []byte{0x02, 0xaa, 0x7e, 0xd3}
+
+	if err := RegisterHDKeyID(hdKeyIDZpub, hdKeyIDZprv); err != nil {
+		t.Fatalf("RegisterHDKeyID: expected no error, got %v", err)
+	}
+
+	got, err := HDPrivateKeyToPublicKeyID(hdKeyIDZprv)
+	if err != nil {
+		t.Fatalf("HDPrivateKeyToPublicKeyID: expected no error, got %v", err)
+	}
+
+	if !bytes.Equal(got, hdKeyIDZpub) {
+		t.Fatalf("HDPrivateKeyToPublicKeyID: expected result %v, got %v",
+			hdKeyIDZpub, got)
+	}
+}
+
+func TestInvalidHDKeyID(t *testing.T) {
+	t.Parallel()
+
+	prvValid := []byte{0x02, 0xaa, 0x7a, 0x99}
+	pubValid := []byte{0x02, 0xaa, 0x7e, 0xd3}
+	prvInvalid := []byte{0x00}
+	pubInvalid := []byte{0x00}
+
+	if err := RegisterHDKeyID(pubInvalid, prvValid); err != ErrInvalidHDKeyID {
+		t.Fatalf("RegisterHDKeyID: want err ErrInvalidHDKeyID, got %v", err)
+	}
+
+	if err := RegisterHDKeyID(pubValid, prvInvalid); err != ErrInvalidHDKeyID {
+		t.Fatalf("RegisterHDKeyID: want err ErrInvalidHDKeyID, got %v", err)
+	}
+
+	if err := RegisterHDKeyID(pubInvalid, prvInvalid); err != ErrInvalidHDKeyID {
+		t.Fatalf("RegisterHDKeyID: want err ErrInvalidHDKeyID, got %v", err)
+	}
+
+	// FIXME: The error type should be changed to ErrInvalidHDKeyID.
+	if _, err := HDPrivateKeyToPublicKeyID(prvInvalid); err != ErrUnknownHDKeyID {
+		t.Fatalf("HDPrivateKeyToPublicKeyID: want err ErrUnknownHDKeyID, got %v", err)
+	}
+}