diff --git a/transaction_test.go b/transaction_test.go
index 03a94b4bc..1f319e682 100644
--- a/transaction_test.go
+++ b/transaction_test.go
@@ -75,12 +75,12 @@ func TestNewTransactionFromTrits(t *testing.T) {
 }
 
 func TestNonce(t *testing.T) {
-	var trytes Trytes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
+	var trytes Trytes = "999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999AUFXOAEMTCSNCXJGFNNEUHD999QTAEMFUCKZJXZEOBXMCOOLMDMFXQESMFWYGRNDETXOTVZLZJBPNIRO9SFNEZG999999999999999999999JOONY9999999999999999999999WIZKPYD99999999999C99999999FKXIDJJNAOQEWYCSL9KWGJRXVNWAT99YHPEXC9SHCDGAVCFLLXJLXZWDTUPSLVLKZT9QZFQQWLXL9GBGDOJSHGFFLPXHSBEKAXEDIOKUEMYBYMTRGCRMGEFREMGCAKBWZL9ZOUSYDIEPKWPCHFBHVOOOXWXQM99999XZSBICKABLTERXWIBESQJCD9CVJMJYVCVVTGEORVF9V9XEHLJSUXGOQBEXDKIHMPXMQWRDLAM9FXA9999BINNY9999999999999999999999CEPV9KWJE999999999MMMMMMMMMJA999IEK9999999999999999999"
 	tx, err := NewTransaction(trytes)
 	if err != nil {
 		t.Fatal(err)
 	}
-	if !tx.HasValidNonce(18) {
+	if !tx.HasValidNonce(DefaultMinWeightMagnitude) {
 		t.Error("cannot validate nonce")
 	}
 }
@@ -90,19 +90,19 @@ func TestTransaction_Hash(t *testing.T) {
 	var trytes1 Trytes = "999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999A9RGRKVGWMWMKOLVMDFWJUHNUNYWZTJADGGPZGXNLERLXYWJE9WQHWWBMCPZMVVMJUMWWBLZLNMLDCGDJ999999999999999999999999999999999999999999999999999999YGYQIVD99999999999999999999TXEFLKNPJRBYZPORHZU9CEMFIFVVQBUSTDGSJCZMBTZCDTTJVUFPTCCVHHORPMGCURKTH9VGJIXUQJVHK999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999"
 	//hash1_p27 := Trytes("IPQYUNLDGKCLJVEJGVVISSQYVDJJWOXCW9RZXIDFKMBXDVZDXFBZNZJKBSTIMBKAXHFTGETEIPTZGNTJK")
 	hash1_p81 := Trytes("WZWSSZGBNFPYFYVHQQUKFJYBIEEPOXMPVOWYPRMRJBQVXJOSBXCAWJTXSCGRZX9VTFJJZVXTWWYDWONQQ")
-	doTransactionHashTest(t,trytes1,hash1_p81)
+	doTransactionHashTest(t, trytes1, hash1_p81)
 
 	var trytes2 Trytes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
 	//hash2_p27 := Trytes("MRYSIXABICSX9XQSLPAPQHGAPCMBDQZXH9EOHPLL9LFQNUDTETNQFUJO9DPHTNPJI9BTQH9RM9I999999")
 	hash2_p81 := Trytes("WPM9JCTQH9QHBHBJCODWDNPSLFLQDZADRAEZTZDL9OEGTVRZARVLVJHZIMPBPCTAIYJKWTUSRKNNTMFOQ")
-	doTransactionHashTest(t,trytes2,hash2_p81)
+	doTransactionHashTest(t, trytes2, hash2_p81)
 
 }
 
 func doTransactionHashTest(t *testing.T, trytes Trytes, hash_p81 Trytes) {
 	// test input trytes hash
 	if trytes.Hash() != hash_p81 {
-		t.Errorf("trytes p81 hash is illegal %s\n",trytes.Hash())
+		t.Errorf("trytes p81 hash is illegal %s\n", trytes.Hash())
 	}
 	// create tx from trytes
 	tx, err := NewTransaction(trytes)
@@ -110,9 +110,7 @@ func doTransactionHashTest(t *testing.T, trytes Trytes, hash_p81 Trytes) {
 		t.Fatal(err)
 	}
 	// test tx hash
-    if (tx.Hash() != hash_p81) {
-		t.Errorf("tx p81 hash is illegal %s\n",tx.Hash())
+	if tx.Hash() != hash_p81 {
+		t.Errorf("tx p81 hash is illegal %s\n", tx.Hash())
 	}
 }
-
-
diff --git a/transfer.go b/transfer.go
index 86c332d5f..148ed7dee 100644
--- a/transfer.go
+++ b/transfer.go
@@ -129,8 +129,8 @@ func (a *AddressInfo) Address() (Address, error) {
 	return NewAddress(a.Seed, a.Index, a.Security)
 }
 
-//Key makes Key from address infos.
-func (a *AddressInfo) Key() Trytes {
+// Key makes Key from address infos.
+func (a *AddressInfo) Key() (Trytes, error) {
 	return NewKey(a.Seed, a.Index, a.Security)
 }
 
@@ -260,7 +260,10 @@ func signInputs(inputs []AddressInfo, bundle Bundle) error {
 			}
 		}
 		// Get corresponding private key of address
-		key := ai.Key()
+		key, err := ai.Key()
+		if err != nil {
+			return err
+		}
 		//  Calculate the new signatureFragment with the first bundle fragment
 		bundle[i].SignatureMessageFragment = Sign(nHash[:27], key[:6561/3])