1 files changed, 27 insertions, 3 deletions
diff --git a/swarm/storage/mru/resource_sign.go b/swarm/storage/mru/resource_sign.go
index c6185a3bb..a9f7cb629 100644
--- a/swarm/storage/mru/resource_sign.go
+++ b/swarm/storage/mru/resource_sign.go
@@ -23,20 +23,44 @@ import (
 	"github.com/ethereum/go-ethereum/crypto"
 )
 
-// Signs resource updates
+const signatureLength = 65
+
+// Signature is an alias for a static byte array with the size of a signature
+type Signature [signatureLength]byte
+
+// Signer signs Mutable Resource update payloads
 type Signer interface {
 	Sign(common.Hash) (Signature, error)
+	Address() common.Address
 }
 
+// GenericSigner implements the Signer interface
+// It is the vanilla signer that probably should be used in most cases
 type GenericSigner struct {
 	PrivKey *ecdsa.PrivateKey
+	address common.Address
 }
 
-func (self *GenericSigner) Sign(data common.Hash) (signature Signature, err error) {
-	signaturebytes, err := crypto.Sign(data.Bytes(), self.PrivKey)
+// NewGenericSigner builds a signer that will sign everything with the provided private key
+func NewGenericSigner(privKey *ecdsa.PrivateKey) *GenericSigner {
+	return &GenericSigner{
+		PrivKey: privKey,
+		address: crypto.PubkeyToAddress(privKey.PublicKey),
+	}
+}
+
+// Sign signs the supplied data
+// It wraps the ethereum crypto.Sign() method
+func (s *GenericSigner) Sign(data common.Hash) (signature Signature, err error) {
+	signaturebytes, err := crypto.Sign(data.Bytes(), s.PrivKey)
 	if err != nil {
 		return
 	}
 	copy(signature[:], signaturebytes)
 	return
 }
+
+// PublicKey returns the public key of the signer's private key
+func (s *GenericSigner) Address() common.Address {
+	return s.address
+}