diff --git a/fints4javaLib/src/main/kotlin/net/dankito/fints/messages/Nachrichtenteil.kt b/fints4javaLib/src/main/kotlin/net/dankito/fints/messages/Nachrichtenteil.kt
index 9aff09ef..181f8cd8 100644
--- a/fints4javaLib/src/main/kotlin/net/dankito/fints/messages/Nachrichtenteil.kt
+++ b/fints4javaLib/src/main/kotlin/net/dankito/fints/messages/Nachrichtenteil.kt
@@ -8,7 +8,7 @@ abstract class Nachrichtenteil(protected val messageUtils: MessageUtils = Messag
     abstract fun format(): String
 
 
-    open fun maskMessagePart(messagePart: String, separator: String): String {
+    open fun maskMessagePart(messagePart: String, separators: List<String>): String {
 
         var maskedMessagePart = messagePart
         val binaryDataRanges = messageUtils.findBinaryDataRanges(messagePart)
@@ -20,9 +20,24 @@ abstract class Nachrichtenteil(protected val messageUtils: MessageUtils = Messag
             .maskCharacterAtIndices(maskedMessagePart, Separators.MaskingCharacter, unmaskedMaskingCharacterIndices)
 
 
-        val separatorIndices = messageUtils.findSeparatorIndices(maskedMessagePart, separator, binaryDataRanges)
+        separators.forEach { separator ->
+            maskedMessagePart = maskSeparators(maskedMessagePart, separator, binaryDataRanges)
+        }
 
-        return messageUtils.maskCharacterAtIndices(maskedMessagePart, separator, separatorIndices)
+        maskedMessagePart = maskSeparators(maskedMessagePart, Separators.DataElementGroupsSeparator, binaryDataRanges)
+
+        return maskedMessagePart
+    }
+
+    protected open fun maskSeparators(unmaskedMessagePart: String, separator: String, binaryDataRanges: List<IntRange>): String {
+
+        val separatorIndices = messageUtils.findSeparatorIndices(unmaskedMessagePart, separator, binaryDataRanges)
+
+        if (separatorIndices.isNotEmpty()) {
+            return messageUtils.maskCharacterAtIndices(unmaskedMessagePart, separator, separatorIndices)
+        }
+
+        return unmaskedMessagePart
     }
 
 }
\ No newline at end of file
diff --git a/fints4javaLib/src/main/kotlin/net/dankito/fints/messages/datenelemente/basisformate/TextDatenelement.kt b/fints4javaLib/src/main/kotlin/net/dankito/fints/messages/datenelemente/basisformate/TextDatenelement.kt
index 04ad4da0..eb6f3feb 100644
--- a/fints4javaLib/src/main/kotlin/net/dankito/fints/messages/datenelemente/basisformate/TextDatenelement.kt
+++ b/fints4javaLib/src/main/kotlin/net/dankito/fints/messages/datenelemente/basisformate/TextDatenelement.kt
@@ -25,7 +25,7 @@ abstract class TextDatenelement(val value: String?, existenzstatus: Existenzstat
     }
 
     protected open fun formatValue(value: String): String {
-        return maskMessagePart(value, Separators.DataElementsSeparator) // may overwritten in sub classes
+        return maskMessagePart(value, Separators.AllSeparators) // may overwritten in sub classes
     }
 
 
diff --git a/fints4javaLib/src/test/kotlin/net/dankito/fints/messages/datenelemente/basisformate/TextDatenelementTest.kt b/fints4javaLib/src/test/kotlin/net/dankito/fints/messages/datenelemente/basisformate/TextDatenelementTest.kt
index 4bbad140..b128b09f 100644
--- a/fints4javaLib/src/test/kotlin/net/dankito/fints/messages/datenelemente/basisformate/TextDatenelementTest.kt
+++ b/fints4javaLib/src/test/kotlin/net/dankito/fints/messages/datenelemente/basisformate/TextDatenelementTest.kt
@@ -1,6 +1,8 @@
 package net.dankito.fints.messages.datenelemente.basisformate
 
 import net.dankito.fints.messages.Existenzstatus
+import net.dankito.fints.messages.datenelementgruppen.implementierte.signatur.SicherheitsidentifikationDetails
+import org.assertj.core.api.Assertions.assertThat
 import org.junit.Test
 
 
@@ -59,6 +61,80 @@ class TextDatenelementTest {
     }
 
 
+    @Test
+    fun maskDataElementsSeparator() {
+
+        // given
+        val customerSystemIdWithDataElementsSeparator = "f8Clj:x3BG4BAACI/459llkXrAQA"
+
+        val expected = "1::" + customerSystemIdWithDataElementsSeparator.replace(":", "?:")
+
+        val underTest = SicherheitsidentifikationDetails(customerSystemIdWithDataElementsSeparator)
+
+        // when
+        val result = underTest.format()
+
+
+        // then
+        assertThat(result).isEqualTo(expected)
+    }
+
+    @Test
+    fun maskDataElementGroupsSeparator() {
+
+        // given
+        val customerSystemIdWithDataElementGroupsSeparator = "f8Clj+x3BG4BAACI/459llkXrAQA"
+
+        val expected = "1::" + customerSystemIdWithDataElementGroupsSeparator.replace("+", "?+")
+
+        val underTest = SicherheitsidentifikationDetails(customerSystemIdWithDataElementGroupsSeparator)
+
+        // when
+        val result = underTest.format()
+
+
+        // then
+        assertThat(result).isEqualTo(expected)
+    }
+
+    @Test
+    fun maskSegmentsSeparator() {
+
+        // given
+        val customerSystemIdWithSegmentsSeparator = "f8Clj\'x3BG4BAACI/459llkXrAQA"
+
+        val expected = "1::" + customerSystemIdWithSegmentsSeparator.replace("'", "?'")
+
+        val underTest = SicherheitsidentifikationDetails(customerSystemIdWithSegmentsSeparator)
+
+        // when
+        val result = underTest.format()
+
+
+        // then
+        assertThat(result).isEqualTo(expected)
+    }
+
+    @Test
+    fun maskMaskingCharacter() {
+
+        // given
+        val customerSystemIdWithMaskingCharacter = "f8Clj?x3BG4BAACI/459llkXrAQA"
+
+        val expected = "1::" + customerSystemIdWithMaskingCharacter.replace("?", "??")
+
+        val underTest = SicherheitsidentifikationDetails(customerSystemIdWithMaskingCharacter)
+
+
+        // when
+        val result = underTest.format()
+
+
+        // then
+        assertThat(result).isEqualTo(expected)
+    }
+
+
     private fun createTextDatenelement(text: String): TextDatenelement {
         return object : TextDatenelement(text, Existenzstatus.Mandatory) { }
     }