refactor: use common.NewRandomString() for generating keyshareserver usernames

internal/common/common.go

@@ -26,9 +26,10 @@ var Logger *logrus.Logger
 var ForceHTTPS = true
 
 const (
-	sessionChars       = "abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ0123456789"
+	AlphanumericChars = "abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ0123456789"
+	NumericChars      = "0123456789"
+
 	sessionTokenLength = 20
-	pairingCodeChars   = "0123456789"
 	pairingCodeLength  = 4
 )
 
@@ -276,14 +277,14 @@ type SSECtx struct {
 }
 
 func NewSessionToken() string {
-	return newRandomString(sessionTokenLength, sessionChars)
+	return NewRandomString(sessionTokenLength, AlphanumericChars)
 }
 
 func NewPairingCode() string {
-	return newRandomString(pairingCodeLength, pairingCodeChars)
+	return NewRandomString(pairingCodeLength, NumericChars)
 }
 
-func newRandomString(count int, characterSet string) string {
+func NewRandomString(count int, characterSet string) string {
 	r := make([]byte, count)
 	_, err := rand.Read(r)
 	if err != nil {

server/keyshare/keyshareserver/server.go

@@ -456,8 +456,7 @@ func (s *Server) handleRegister(w http.ResponseWriter, r *http.Request) {
 
 func (s *Server) register(msg irma.KeyshareEnrollment) (*irma.Qr, error) {
 	// Generate keyshare server account
-	username := common.NewSessionToken() // TODO use newRandomString() for this when shoulder-surf is merged
-	username = username[:12]
+	username := common.NewRandomString(12, common.AlphanumericChars)
 
 	secrets, err := s.core.NewUserSecrets(msg.Pin)
 	if err != nil {