diff --git a/poi/src/main/java/org/apache/poi/poifs/crypt/agile/CertificateKeyEncryptor.java b/poi/src/main/java/org/apache/poi/poifs/crypt/agile/CertificateKeyEncryptor.java
index 938b04f466..706ec93f2e 100644
--- a/poi/src/main/java/org/apache/poi/poifs/crypt/agile/CertificateKeyEncryptor.java
+++ b/poi/src/main/java/org/apache/poi/poifs/crypt/agile/CertificateKeyEncryptor.java
@@ -17,13 +17,12 @@
 
 package org.apache.poi.poifs.crypt.agile;
 
-import static org.apache.poi.poifs.crypt.agile.EncryptionDocument.getBinAttr;
-import static org.apache.poi.poifs.crypt.agile.EncryptionDocument.setBinAttr;
-
 import org.apache.poi.EncryptedDocumentException;
 import org.w3c.dom.Document;
 import org.w3c.dom.Element;
 
+import static org.apache.poi.poifs.crypt.agile.EncryptionDocument.*;
+
 public class CertificateKeyEncryptor {
 
     /**
@@ -60,9 +59,9 @@ public class CertificateKeyEncryptor {
 
     void write(Element encryption) {
         Document doc = encryption.getOwnerDocument();
-        Element keyEncryptor = (Element) encryption.appendChild(doc.createElement("keyEncryptor"));
+        Element keyEncryptor = (Element) encryption.appendChild(doc.createElementNS(ENC_NS, "keyEncryptor"));
         keyEncryptor.setAttribute("uri", KeyEncryptor.CERT_NS);
-        Element encryptedKey = (Element) keyEncryptor.appendChild(doc.createElement("c:encryptedKey"));
+        Element encryptedKey = (Element) keyEncryptor.appendChild(doc.createElementNS(KeyEncryptor.CERT_NS, "c:encryptedKey"));
 
         setBinAttr(encryptedKey, "encryptedKeyValue", encryptedKeyValue);
         setBinAttr(encryptedKey, "x509Certificate", x509Certificate);
diff --git a/poi/src/main/java/org/apache/poi/poifs/crypt/agile/DataIntegrity.java b/poi/src/main/java/org/apache/poi/poifs/crypt/agile/DataIntegrity.java
index 5d067b0232..37c90e4904 100644
--- a/poi/src/main/java/org/apache/poi/poifs/crypt/agile/DataIntegrity.java
+++ b/poi/src/main/java/org/apache/poi/poifs/crypt/agile/DataIntegrity.java
@@ -59,7 +59,7 @@ public class DataIntegrity {
 
     void write(Element encryption) {
         Document doc = encryption.getOwnerDocument();
-        Element dataIntegrity = (Element)encryption.appendChild(doc.createElement("dataIntegrity"));
+        Element dataIntegrity = (Element)encryption.appendChild(doc.createElementNS(ENC_NS, "dataIntegrity"));
         setBinAttr(dataIntegrity, "encryptedHmacKey", encryptedHmacKey);
         setBinAttr(dataIntegrity, "encryptedHmacValue", encryptedHmacValue);
     }
diff --git a/poi/src/main/java/org/apache/poi/poifs/crypt/agile/EncryptionDocument.java b/poi/src/main/java/org/apache/poi/poifs/crypt/agile/EncryptionDocument.java
index fd5e53a2b9..659507a574 100644
--- a/poi/src/main/java/org/apache/poi/poifs/crypt/agile/EncryptionDocument.java
+++ b/poi/src/main/java/org/apache/poi/poifs/crypt/agile/EncryptionDocument.java
@@ -76,7 +76,7 @@ public class EncryptionDocument {
         if (dataIntegrity != null) {
             dataIntegrity.write(encryption);
         }
-        Element keyEncryptors = (Element)encryption.appendChild(doc.createElement("keyEncryptors"));
+        Element keyEncryptors = (Element)encryption.appendChild(doc.createElementNS(ENC_NS, "keyEncryptors"));
         boolean hasPass = false;
         boolean hasCert = false;
         for (KeyEncryptor ke : this.keyEncryptors) {
diff --git a/poi/src/main/java/org/apache/poi/poifs/crypt/agile/KeyData.java b/poi/src/main/java/org/apache/poi/poifs/crypt/agile/KeyData.java
index fba57eb2c4..5ed0d14db3 100644
--- a/poi/src/main/java/org/apache/poi/poifs/crypt/agile/KeyData.java
+++ b/poi/src/main/java/org/apache/poi/poifs/crypt/agile/KeyData.java
@@ -71,7 +71,7 @@ public class KeyData {
 
     void write(Element encryption) {
         Document doc = encryption.getOwnerDocument();
-        Element keyData = (Element)encryption.appendChild(doc.createElement("keyData"));
+        Element keyData = (Element)encryption.appendChild(doc.createElementNS(ENC_NS, "keyData"));
         setIntAttr(keyData, "saltSize", saltSize);
         setIntAttr(keyData, "blockSize", blockSize);
         setIntAttr(keyData, "keyBits", keyBits);
diff --git a/poi/src/main/java/org/apache/poi/poifs/crypt/agile/PasswordKeyEncryptor.java b/poi/src/main/java/org/apache/poi/poifs/crypt/agile/PasswordKeyEncryptor.java
index 1e3f8640ff..c31caaba40 100644
--- a/poi/src/main/java/org/apache/poi/poifs/crypt/agile/PasswordKeyEncryptor.java
+++ b/poi/src/main/java/org/apache/poi/poifs/crypt/agile/PasswordKeyEncryptor.java
@@ -17,12 +17,6 @@
 
 package org.apache.poi.poifs.crypt.agile;
 
-import static org.apache.poi.poifs.crypt.agile.EncryptionDocument.getBinAttr;
-import static org.apache.poi.poifs.crypt.agile.EncryptionDocument.getIntAttr;
-import static org.apache.poi.poifs.crypt.agile.EncryptionDocument.setAttr;
-import static org.apache.poi.poifs.crypt.agile.EncryptionDocument.setBinAttr;
-import static org.apache.poi.poifs.crypt.agile.EncryptionDocument.setIntAttr;
-
 import org.apache.poi.EncryptedDocumentException;
 import org.apache.poi.poifs.crypt.ChainingMode;
 import org.apache.poi.poifs.crypt.CipherAlgorithm;
@@ -30,6 +24,9 @@ import org.apache.poi.poifs.crypt.HashAlgorithm;
 import org.w3c.dom.Document;
 import org.w3c.dom.Element;
 
+import static org.apache.poi.poifs.crypt.agile.EncryptionDocument.*;
+import static org.apache.poi.poifs.crypt.agile.KeyEncryptor.PASS_NS;
+
 public class PasswordKeyEncryptor {
 
     /**
@@ -124,9 +121,9 @@ public class PasswordKeyEncryptor {
 
     void write(Element encryption) {
         Document doc = encryption.getOwnerDocument();
-        Element keyEncryptor = (Element) encryption.appendChild(doc.createElement("keyEncryptor"));
-        keyEncryptor.setAttribute("uri", KeyEncryptor.PASS_NS);
-        Element encryptedKey = (Element) keyEncryptor.appendChild(doc.createElement("p:encryptedKey"));
+        Element keyEncryptor = (Element) encryption.appendChild(doc.createElementNS(ENC_NS, "keyEncryptor"));
+        keyEncryptor.setAttribute("uri", PASS_NS);
+        Element encryptedKey = (Element) keyEncryptor.appendChild(doc.createElementNS(PASS_NS, "p:encryptedKey"));
 
         setIntAttr(encryptedKey, "saltSize", saltSize);
         setIntAttr(encryptedKey, "blockSize", blockSize);
diff --git a/poi/src/main/java9/module-info.class b/poi/src/main/java9/module-info.class
index a27868cdf4..7ca4ecd882 100644
Binary files a/poi/src/main/java9/module-info.class and b/poi/src/main/java9/module-info.class differ