diff --git a/cmd/signer/api.go b/cmd/signer/api.go
index c7926276bd..2e07dd13ec 100644
--- a/cmd/signer/api.go
+++ b/cmd/signer/api.go
@@ -36,9 +36,6 @@ import (
 	"github.com/ethereum/go-ethereum/rlp"
 )
 
-//type Stringer interface  {String()}
-
-
 type SignerAPI struct {
 	chainID *big.Int
 	am      *accounts.Manager
@@ -52,75 +49,67 @@ type Metadata struct {
 	scheme string
 }
 
-type credPreference int
-
-const (
-	forgetPw credPreference = iota
-	rememberPwNow
+// types for the requests/response types
+type (
+	// SignTxRequest contains info about a transaction to sign
+	SignTxRequest struct {
+		transaction *types.Transaction
+		from        accounts.Account
+		callinfo    fmt.Stringer
+	}
+	// SignTxResponse result from SignTxRequest
+	SignTxResponse struct {
+		hash     common.Hash
+		approved bool
+		pw       string
+	}
+	// ExportRequest info about query to export accounts
+	ExportRequest struct {
+		account accounts.Account
+		file    string
+	}
+	// ExportResponse response to export-request
+	ExportResponse struct {
+		approved bool
+	}
+	// ImportRequest info about request to import an account
+	ImportRequest struct {
+		account accounts.Account
+	}
+	ImportResponse struct {
+		approved    bool
+		oldPassword string
+		newPassword string
+	}
+	SignDataRequest struct {
+		account accounts.Account
+		rawdata hexutil.Bytes
+		message string
+		hash    hexutil.Bytes
+	}
+	SignDataResponse struct {
+		approved bool
+		pw       string
+	}
+	NewAccountRequest  struct{}
+	NewAccountResponse struct {
+		approved bool
+		pw       string
+	}
+	ListRequest struct {
+		accounts []Account
+	}
+	ListResponse struct {
+		accounts []Account
+	}
 )
 
-type Credentials struct {
-	password string
-}
-
-// SignTxRequest contains info about a transaction to sign
-type SignTxRequest struct {
-	transaction *types.Transaction
-	from        accounts.Account
-	callinfo    fmt.Stringer
-}
-type SignTxResponse struct {
-	hash     common.Hash
-	approved bool
-	pw       string
-}
-
-type ExportRequest struct {
-	account accounts.Account
-	file    string
-}
-type ExportResponse struct {
-	approved bool
-}
-
-type ImportRequest struct {
-	account accounts.Account
-}
-
-type ImportResponse struct {
-	approved    bool
-	oldPassword string
-	newPassword string
-}
-
-type SignDataRequest struct {
-	account accounts.Account
-	rawdata hexutil.Bytes
-	message string
-	hash    hexutil.Bytes
-}
-type SignDataResponse struct {
-	approved bool
-	pw       string
-}
-
-type NewAccountRequest struct{}
-type NewAccountResponse struct {
-	approved bool
-	pw       string
-}
-
-type ListRequest struct {
-	accounts []Account
-}
-type ListResponse struct {
-	accounts []Account
-}
-type errorWrapper struct{
+type errorWrapper struct {
 	msg string
 	err error
 }
-func (ew errorWrapper) String() string{
+
+func (ew errorWrapper) String() string {
 	return fmt.Sprintf("%s\n%s", ew.msg, ew.err)
 }
 
@@ -281,16 +270,16 @@ func (api *SignerAPI) SignTransaction(ctx context.Context, from common.Address,
 	}
 
 	req := SignTxRequest{transaction: tx, from: acc}
-	if len(tx.Data()) > 3{
+	if len(tx.Data()) > 3 {
 		var abidef string
 
 		// Try to make sense of the data
 		abidef, err = lookupABI(tx.Data()[:4])
-		if err != nil{
+		if err != nil {
 			req.callinfo = errorWrapper{"Warning! Could not locate ABI", err}
-		}else{
-			req.callinfo, err  = parseCallData(tx.Data(),abidef)
-			if err != nil{
+		} else {
+			req.callinfo, err = parseCallData(tx.Data(), abidef)
+			if err != nil {
 				req.callinfo = errorWrapper{"Warning! Could not validate ABI-data against calldata", err}
 			}
 		}
diff --git a/cmd/signer/cliui.go b/cmd/signer/cliui.go
index 30f0ba67ed..1b22face47 100644
--- a/cmd/signer/cliui.go
+++ b/cmd/signer/cliui.go
@@ -24,14 +24,16 @@ import (
 	"github.com/ethereum/go-ethereum/common"
 	"github.com/ethereum/go-ethereum/log"
 	"golang.org/x/crypto/ssh/terminal"
+	"sync"
 )
 
 type CommandlineUI struct {
 	in *bufio.Reader
+	mu sync.Mutex
 }
 
 func NewCommandlineUI() *CommandlineUI {
-	return &CommandlineUI{bufio.NewReader(os.Stdin)}
+	return &CommandlineUI{in: bufio.NewReader(os.Stdin)}
 }
 
 // readString reads a single line from stdin, trimming if from spaces, enforcing
@@ -76,15 +78,18 @@ func showMetadata(metadata Metadata) {
 
 // ApproveTx prompt the user for confirmation to request to sign transaction
 func (ui *CommandlineUI) ApproveTx(request *SignTxRequest, metadata Metadata, ch chan SignTxResponse) {
-
+	ui.mu.Lock()
+	defer ui.mu.Unlock()
 	weival := request.transaction.Value()
 
 	fmt.Printf("--------- Transaction request-------------\n")
 	fmt.Printf("to:    %v\n", request.transaction.To().Hex())
 	fmt.Printf("from:  %v\n", request.from.Address.Hex())
 	fmt.Printf("value: %v wei\n", weival)
-	fmt.Printf("data:  %v\n", common.Bytes2Hex(request.transaction.Data()))
-	if request.callinfo != nil{
+	if len(request.transaction.Data()) > 0{
+		fmt.Printf("data:  %v\n", common.Bytes2Hex(request.transaction.Data()))
+	}
+	if request.callinfo != nil {
 		fmt.Printf("\nNote: This transaction contains data. Review abi-decoding info below:")
 		fmt.Printf("\nCall info:\n\t%v\n", request.callinfo.String())
 
@@ -98,6 +103,8 @@ func (ui *CommandlineUI) ApproveTx(request *SignTxRequest, metadata Metadata, ch
 
 // ApproveSignData prompt the user for confirmation to request to sign data
 func (ui *CommandlineUI) ApproveSignData(request *SignDataRequest, metadata Metadata, ch chan SignDataResponse) {
+	ui.mu.Lock()
+	defer ui.mu.Unlock()
 
 	fmt.Printf("-------- Sign data request--------------\n")
 	fmt.Printf("account:  %x\n", request.account.Address)
@@ -111,6 +118,9 @@ func (ui *CommandlineUI) ApproveSignData(request *SignDataRequest, metadata Meta
 
 // ApproveExport prompt the user for confirmation to export encrypted account json
 func (ui *CommandlineUI) ApproveExport(request *ExportRequest, metadata Metadata, ch chan ExportResponse) {
+	ui.mu.Lock()
+	defer ui.mu.Unlock()
+
 	fmt.Printf("-------- Export account request--------------\n")
 	fmt.Printf("A request has been made to export the (encrypted) keyfile\n")
 	fmt.Printf("Approving this operation means that the caller obtains the (encrypted) contents\n")
@@ -124,6 +134,9 @@ func (ui *CommandlineUI) ApproveExport(request *ExportRequest, metadata Metadata
 
 // ApproveImport prompt the user for confirmation to import account json
 func (ui *CommandlineUI) ApproveImport(request *ImportRequest, metadata Metadata, ch chan ImportResponse) {
+	ui.mu.Lock()
+	defer ui.mu.Unlock()
+
 	fmt.Printf("-------- Export account request--------------\n")
 	fmt.Printf("A request has been made to import an encrypted keyfile\n")
 	fmt.Printf("-------------------------------------------\n")
@@ -135,6 +148,9 @@ func (ui *CommandlineUI) ApproveImport(request *ImportRequest, metadata Metadata
 // the list of accounts to list can be modified by the ui
 func (ui *CommandlineUI) ApproveListing(request *ListRequest, metadata Metadata, ch chan ListResponse) {
 
+	ui.mu.Lock()
+	defer ui.mu.Unlock()
+
 	fmt.Printf("-------- List account request--------------\n")
 	fmt.Printf("A request has been made to list all accounts. \n")
 	fmt.Printf("You can select which accounts the caller can see\n")
@@ -152,6 +168,10 @@ func (ui *CommandlineUI) ApproveListing(request *ListRequest, metadata Metadata,
 
 // ApproveNewAccount prompt the user for confirmation to create new account, and reveal to caller
 func (ui *CommandlineUI) ApproveNewAccount(requst *NewAccountRequest, metadata Metadata, ch chan NewAccountResponse) {
+
+	ui.mu.Lock()
+	defer ui.mu.Unlock()
+
 	fmt.Printf("-------- New account request--------------\n")
 	fmt.Printf("A request has been made to create a new. \n")
 	fmt.Printf("Approving this operation means that a new account is created,\n")