1 files changed, 53 insertions, 0 deletions
diff --git a/accounts/abi/bind/auth.go b/accounts/abi/bind/auth.go
new file mode 100644
index 000000000..e0491497c
--- /dev/null
+++ b/accounts/abi/bind/auth.go
@@ -0,0 +1,53 @@
+// Copyright 2016 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 bind
+
+import (
+	"errors"
+
+	"github.com/ethereum/go-ethereum/common"
+	"github.com/ethereum/go-ethereum/core/types"
+	"github.com/ethereum/go-ethereum/crypto"
+)
+
+// NewTransactor is a utility method to easily create a transaction signer from
+// an encrypted json key file and the associated passphrase.
+func NewTransactor(keyjson string, passphrase string) (*TransactOpts, error) {
+	key, err := crypto.DecryptKey([]byte(keyjson), passphrase)
+	if err != nil {
+		return nil, err
+	}
+	return NewKeyedTransactor(key), nil
+}
+
+// NewKeyedTransactor is a utility method to easily create a transaction signer
+// from a plain go-ethereum crypto key.
+func NewKeyedTransactor(key *crypto.Key) *TransactOpts {
+	return &TransactOpts{
+		Account: key.Address,
+		Signer: func(address common.Address, tx *types.Transaction) (*types.Transaction, error) {
+			if address != key.Address {
+				return nil, errors.New("not authorized to sign this account")
+			}
+			signature, err := crypto.Sign(tx.SigHash().Bytes(), key.PrivateKey)
+			if err != nil {
+				return nil, err
+			}
+			return tx.WithSignature(signature)
+		},
+	}
+}