1 files changed, 152 insertions, 0 deletions
diff --git a/accounts/hd.go b/accounts/hd.go
new file mode 100644
index 0000000..75c4761
--- /dev/null
+++ b/accounts/hd.go
@@ -0,0 +1,152 @@
+// Copyright 2017 The go-ethereum Authors
+// This file is part of the go-ethereum library.
+//
+// The go-ethereum library is free software: you can redistribute it and/or modify
+// it under the terms of the GNU Lesser General Public License as published by
+// the Free Software Foundation, either version 3 of the License, or
+// (at your option) any later version.
+//
+// The go-ethereum library is distributed in the hope that it will be useful,
+// but WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+// GNU Lesser General Public License for more details.
+//
+// You should have received a copy of the GNU Lesser General Public License
+// along with the go-ethereum library. If not, see <http://www.gnu.org/licenses/>.
+
+package accounts
+
+import (
+	"encoding/json"
+	"errors"
+	"fmt"
+	"math"
+	"math/big"
+	"strings"
+)
+
+// DefaultRootDerivationPath is the root path to which custom derivation endpoints
+// are appended. As such, the first account will be at m/44'/60'/0'/0, the second
+// at m/44'/60'/0'/1, etc.
+var DefaultRootDerivationPath = DerivationPath{0x80000000 + 44, 0x80000000 + 60, 0x80000000 + 0, 0}
+
+// DefaultBaseDerivationPath is the base path from which custom derivation endpoints
+// are incremented. As such, the first account will be at m/44'/60'/0'/0/0, the second
+// at m/44'/60'/0'/0/1, etc.
+var DefaultBaseDerivationPath = DerivationPath{0x80000000 + 44, 0x80000000 + 60, 0x80000000 + 0, 0, 0}
+
+// LegacyLedgerBaseDerivationPath is the legacy base path from which custom derivation
+// endpoints are incremented. As such, the first account will be at m/44'/60'/0'/0, the
+// second at m/44'/60'/0'/1, etc.
+var LegacyLedgerBaseDerivationPath = DerivationPath{0x80000000 + 44, 0x80000000 + 60, 0x80000000 + 0, 0}
+
+// DerivationPath represents the computer friendly version of a hierarchical
+// deterministic wallet account derivaion path.
+//
+// The BIP-32 spec https://github.com/bitcoin/bips/blob/master/bip-0032.mediawiki
+// defines derivation paths to be of the form:
+//
+//   m / purpose' / coin_type' / account' / change / address_index
+//
+// The BIP-44 spec https://github.com/bitcoin/bips/blob/master/bip-0044.mediawiki
+// defines that the `purpose` be 44' (or 0x8000002C) for crypto currencies, and
+// SLIP-44 https://github.com/satoshilabs/slips/blob/master/slip-0044.md assigns
+// the `coin_type` 60' (or 0x8000003C) to Ethereum.
+//
+// The root path for Ethereum is m/44'/60'/0'/0 according to the specification
+// from https://github.com/ethereum/EIPs/issues/84, albeit it's not set in stone
+// yet whether accounts should increment the last component or the children of
+// that. We will go with the simpler approach of incrementing the last component.
+type DerivationPath []uint32
+
+// ParseDerivationPath converts a user specified derivation path string to the
+// internal binary representation.
+//
+// Full derivation paths need to start with the `m/` prefix, relative derivation
+// paths (which will get appended to the default root path) must not have prefixes
+// in front of the first element. Whitespace is ignored.
+func ParseDerivationPath(path string) (DerivationPath, error) {
+	var result DerivationPath
+
+	// Handle absolute or relative paths
+	components := strings.Split(path, "/")
+	switch {
+	case len(components) == 0:
+		return nil, errors.New("empty derivation path")
+
+	case strings.TrimSpace(components[0]) == "":
+		return nil, errors.New("ambiguous path: use 'm/' prefix for absolute paths, or no leading '/' for relative ones")
+
+	case strings.TrimSpace(components[0]) == "m":
+		components = components[1:]
+
+	default:
+		result = append(result, DefaultRootDerivationPath...)
+	}
+	// All remaining components are relative, append one by one
+	if len(components) == 0 {
+		return nil, errors.New("empty derivation path") // Empty relative paths
+	}
+	for _, component := range components {
+		// Ignore any user added whitespace
+		component = strings.TrimSpace(component)
+		var value uint32
+
+		// Handle hardened paths
+		if strings.HasSuffix(component, "'") {
+			value = 0x80000000
+			component = strings.TrimSpace(strings.TrimSuffix(component, "'"))
+		}
+		// Handle the non hardened component
+		bigval, ok := new(big.Int).SetString(component, 0)
+		if !ok {
+			return nil, fmt.Errorf("invalid component: %s", component)
+		}
+		max := math.MaxUint32 - value
+		if bigval.Sign() < 0 || bigval.Cmp(big.NewInt(int64(max))) > 0 {
+			if value == 0 {
+				return nil, fmt.Errorf("component %v out of allowed range [0, %d]", bigval, max)
+			}
+			return nil, fmt.Errorf("component %v out of allowed hardened range [0, %d]", bigval, max)
+		}
+		value += uint32(bigval.Uint64())
+
+		// Append and repeat
+		result = append(result, value)
+	}
+	return result, nil
+}
+
+// String implements the stringer interface, converting a binary derivation path
+// to its canonical representation.
+func (path DerivationPath) String() string {
+	result := "m"
+	for _, component := range path {
+		var hardened bool
+		if component >= 0x80000000 {
+			component -= 0x80000000
+			hardened = true
+		}
+		result = fmt.Sprintf("%s/%d", result, component)
+		if hardened {
+			result += "'"
+		}
+	}
+	return result
+}
+
+// MarshalJSON turns a derivation path into its json-serialized string
+func (path DerivationPath) MarshalJSON() ([]byte, error) {
+	return json.Marshal(path.String())
+}
+
+// UnmarshalJSON a json-serialized string back into a derivation path
+func (path *DerivationPath) UnmarshalJSON(b []byte) error {
+	var dp string
+	var err error
+	if err = json.Unmarshal(b, &dp); err != nil {
+		return err
+	}
+	*path, err = ParseDerivationPath(dp)
+	return err
+}