diff --git a/src/main/java/org/qortal/arbitrary/misc/Service.java b/src/main/java/org/qortal/arbitrary/misc/Service.java
index 27557045..e0caa2a5 100644
--- a/src/main/java/org/qortal/arbitrary/misc/Service.java
+++ b/src/main/java/org/qortal/arbitrary/misc/Service.java
@@ -9,7 +9,6 @@ import org.qortal.utils.FilesystemUtils;
 import java.io.File;
 import java.io.IOException;
 import java.nio.charset.StandardCharsets;
-import java.nio.file.Files;
 import java.nio.file.Path;
 import java.nio.file.Paths;
 import java.util.*;
@@ -20,9 +19,9 @@ import static java.util.Arrays.stream;
 import static java.util.stream.Collectors.toMap;
 
 public enum Service {
-    AUTO_UPDATE(1, false, null, false, null),
-    ARBITRARY_DATA(100, false, null, false, null),
-    QCHAT_ATTACHMENT(120, true, 1024*1024L, true, null) {
+    AUTO_UPDATE(1, false, null, false, false, null),
+    ARBITRARY_DATA(100, false, null, false, false, null),
+    QCHAT_ATTACHMENT(120, true, 1024*1024L, true, false, null) {
         @Override
         public ValidationResult validate(Path path) throws IOException {
             ValidationResult superclassResult = super.validate(path);
@@ -47,11 +46,14 @@ public enum Service {
             return ValidationResult.OK;
         }
     },
-    ATTACHMENT(130, false, null, true, null),
-    FILE(140, false, null, true, null),
-    FILES(150, false, null, false, null),
-    CHAIN_DATA(160, true, 239L, true, null),
-    WEBSITE(200, true, null, false, null) {
+    QCHAT_ATTACHMENT_PRIVATE(121, true, 1024*1024L, true, true, null),
+    ATTACHMENT(130, false, 50*1024*1024L, true, false, null),
+    ATTACHMENT_PRIVATE(131, true, 50*1024*1024L, true, true, null),
+    FILE(140, false, null, true, false, null),
+    FILE_PRIVATE(141, true, null, true, true, null),
+    FILES(150, false, null, false, false, null),
+    CHAIN_DATA(160, true, 239L, true, false, null),
+    WEBSITE(200, true, null, false, false, null) {
         @Override
         public ValidationResult validate(Path path) throws IOException {
             ValidationResult superclassResult = super.validate(path);
@@ -73,25 +75,30 @@ public enum Service {
             return ValidationResult.MISSING_INDEX_FILE;
         }
     },
-    GIT_REPOSITORY(300, false, null, false, null),
-    IMAGE(400, true, 10*1024*1024L, true, null),
-    THUMBNAIL(410, true, 500*1024L, true, null),
-    QCHAT_IMAGE(420, true, 500*1024L, true, null),
-    VIDEO(500, false, null, true, null),
-    AUDIO(600, false, null, true, null),
-    QCHAT_AUDIO(610, true, 10*1024*1024L, true, null),
-    QCHAT_VOICE(620, true, 10*1024*1024L, true, null),
-    VOICE(630, true, 10*1024*1024L, true, null),
-    PODCAST(640, false, null, true, null),
-    BLOG(700, false, null, false, null),
-    BLOG_POST(777, false, null, true, null),
-    BLOG_COMMENT(778, true, 500*1024L, true, null),
-    DOCUMENT(800, false, null, true, null),
-    LIST(900, true, null, true, null),
-    PLAYLIST(910, true, null, true, null),
-    APP(1000, true, 50*1024*1024L, false, null),
-    METADATA(1100, false, null, true, null),
-    JSON(1110, true, 25*1024L, true, null) {
+    GIT_REPOSITORY(300, false, null, false, false, null),
+    IMAGE(400, true, 10*1024*1024L, true, false, null),
+    IMAGE_PRIVATE(401, true, 10*1024*1024L, true, true, null),
+    THUMBNAIL(410, true, 500*1024L, true, false, null),
+    QCHAT_IMAGE(420, true, 500*1024L, true, false, null),
+    VIDEO(500, false, null, true, false, null),
+    VIDEO_PRIVATE(501, true, null, true, true, null),
+    AUDIO(600, false, null, true, false, null),
+    AUDIO_PRIVATE(601, true, null, true, true, null),
+    QCHAT_AUDIO(610, true, 10*1024*1024L, true, false, null),
+    QCHAT_VOICE(620, true, 10*1024*1024L, true, false, null),
+    VOICE(630, true, 10*1024*1024L, true, false, null),
+    VOICE_PRIVATE(631, true, 10*1024*1024L, true, true, null),
+    PODCAST(640, false, null, true, false, null),
+    BLOG(700, false, null, false, false, null),
+    BLOG_POST(777, false, null, true, false, null),
+    BLOG_COMMENT(778, true, 500*1024L, true, false, null),
+    DOCUMENT(800, false, null, true, false, null),
+    DOCUMENT_PRIVATE(801, true, null, true, true, null),
+    LIST(900, true, null, true, false, null),
+    PLAYLIST(910, true, null, true, false, null),
+    APP(1000, true, 50*1024*1024L, false, false, null),
+    METADATA(1100, false, null, true, false, null),
+    JSON(1110, true, 25*1024L, true, false, null) {
         @Override
         public ValidationResult validate(Path path) throws IOException {
             ValidationResult superclassResult = super.validate(path);
@@ -110,7 +117,7 @@ public enum Service {
             }
         }
     },
-    GIF_REPOSITORY(1200, true, 25*1024*1024L, false, null) {
+    GIF_REPOSITORY(1200, true, 25*1024*1024L, false, false, null) {
         @Override
         public ValidationResult validate(Path path) throws IOException {
             ValidationResult superclassResult = super.validate(path);
@@ -146,27 +153,30 @@ public enum Service {
             return ValidationResult.OK;
         }
     },
-    STORE(1300, false, null, true, null),
-    PRODUCT(1310, false, null, true, null),
-    OFFER(1330, false, null, true, null),
-    COUPON(1340, false, null, true, null),
-    CODE(1400, false, null, true, null),
-    PLUGIN(1410, false, null, true, null),
-    EXTENSION(1420, false, null, true, null),
-    GAME(1500, false, null, false, null),
-    ITEM(1510, false, null, true, null),
-    NFT(1600, false, null, true, null),
-    DATABASE(1700, false, null, false, null),
-    SNAPSHOT(1710, false, null, false, null),
-    COMMENT(1800, true, 500*1024L, true, null),
-    CHAIN_COMMENT(1810, true, 239L, true, null),
-    MAIL(1900, true, 1024*1024L, true, null),
-    MESSAGE(1910, true, 1024*1024L, true, null);
+    STORE(1300, false, null, true, false, null),
+    PRODUCT(1310, false, null, true, false, null),
+    OFFER(1330, false, null, true, false, null),
+    COUPON(1340, false, null, true, false, null),
+    CODE(1400, false, null, true, false, null),
+    PLUGIN(1410, false, null, true, false, null),
+    EXTENSION(1420, false, null, true, false, null),
+    GAME(1500, false, null, false, false, null),
+    ITEM(1510, false, null, true, false, null),
+    NFT(1600, false, null, true, false, null),
+    DATABASE(1700, false, null, false, false, null),
+    SNAPSHOT(1710, false, null, false, false, null),
+    COMMENT(1800, true, 500*1024L, true, false, null),
+    CHAIN_COMMENT(1810, true, 239L, true, false, null),
+    MAIL(1900, true, 1024*1024L, true, false, null),
+    MAIL_PRIVATE(1901, true, 1024*1024L, true, true, null),
+    MESSAGE(1910, true, 1024*1024L, true, false, null),
+    MESSAGE_PRIVATE(1911, true, 1024*1024L, true, true, null);
 
     public final int value;
     private final boolean requiresValidation;
     private final Long maxSize;
     private final boolean single;
+    private final boolean isPrivate;
     private final List<String> requiredKeys;
 
     private static final Map<Integer, Service> map = stream(Service.values())
@@ -175,11 +185,14 @@ public enum Service {
     // For JSON validation
     private static final ObjectMapper objectMapper = new ObjectMapper();
 
-    Service(int value, boolean requiresValidation, Long maxSize, boolean single, List<String> requiredKeys) {
+    private static final String encryptedDataPrefix = "qortalEncryptedData";
+
+    Service(int value, boolean requiresValidation, Long maxSize, boolean single, boolean isPrivate, List<String> requiredKeys) {
         this.value = value;
         this.requiresValidation = requiresValidation;
         this.maxSize = maxSize;
         this.single = single;
+        this.isPrivate = isPrivate;
         this.requiredKeys = requiredKeys;
     }
 
@@ -203,6 +216,17 @@ public enum Service {
             return ValidationResult.INVALID_FILE_COUNT;
         }
 
+        // Validate private data for single file resources
+        if (this.single) {
+            String dataString = new String(data, StandardCharsets.UTF_8);
+            if (this.isPrivate && !dataString.startsWith(encryptedDataPrefix)) {
+                return ValidationResult.DATA_NOT_ENCRYPTED;
+            }
+            if (!this.isPrivate && dataString.startsWith(encryptedDataPrefix)) {
+                return ValidationResult.DATA_ENCRYPTED;
+            }
+        }
+
         // Validate required keys if needed
         if (this.requiredKeys != null) {
             if (data == null) {
@@ -221,7 +245,8 @@ public enum Service {
     }
 
     public boolean isValidationRequired() {
-        return this.requiresValidation;
+        // We must always validate single file resources, to ensure they are actually a single file
+        return this.requiresValidation || this.single;
     }
 
     public static Service valueOf(int value) {
@@ -242,7 +267,9 @@ public enum Service {
         INVALID_FILE_EXTENSION(6),
         MISSING_DATA(7),
         INVALID_FILE_COUNT(8),
-        INVALID_CONTENT(9);
+        INVALID_CONTENT(9),
+        DATA_NOT_ENCRYPTED(10),
+        DATA_ENCRYPTED(10);
 
         public final int value;
 
diff --git a/src/main/java/org/qortal/controller/arbitrary/ArbitraryDataManager.java b/src/main/java/org/qortal/controller/arbitrary/ArbitraryDataManager.java
index 567dcdd3..9284e672 100644
--- a/src/main/java/org/qortal/controller/arbitrary/ArbitraryDataManager.java
+++ b/src/main/java/org/qortal/controller/arbitrary/ArbitraryDataManager.java
@@ -16,7 +16,6 @@ import org.qortal.arbitrary.misc.Service;
 import org.qortal.controller.Controller;
 import org.qortal.data.transaction.ArbitraryTransactionData;
 import org.qortal.data.transaction.TransactionData;
-import org.qortal.list.ResourceListManager;
 import org.qortal.network.Network;
 import org.qortal.network.Peer;
 import org.qortal.repository.DataException;
diff --git a/src/test/java/org/qortal/test/arbitrary/ArbitraryServiceTests.java b/src/test/java/org/qortal/test/arbitrary/ArbitraryServiceTests.java
index 940b33a9..45960a25 100644
--- a/src/test/java/org/qortal/test/arbitrary/ArbitraryServiceTests.java
+++ b/src/test/java/org/qortal/test/arbitrary/ArbitraryServiceTests.java
@@ -436,4 +436,71 @@ public class ArbitraryServiceTests extends Common {
         assertEquals(ValidationResult.INVALID_FILE_COUNT, service.validate(path));
     }
 
+    @Test
+    public void testValidPrivateData() throws IOException {
+        String dataString = "qortalEncryptedDatabMx4fELNTV+ifJxmv4+GcuOIJOTo+3qAvbWKNY2L1rfla5UBoEcoxbtjgZ9G7FLPb8V/Qfr0bfKWfvMmN06U/pgUdLuv2mGL2V0D3qYd1011MUzGdNG1qERjaCDz8GAi63+KnHHjfMtPgYt6bcqjs4CNV+ZZ4dIt3xxHYyVEBNc=";
+
+        // Write the data a single file in a temp path
+        Path path = Files.createTempDirectory("testValidPrivateData");
+        Path filePath = Paths.get(path.toString(), "test");
+        filePath.toFile().deleteOnExit();
+
+        BufferedWriter writer = new BufferedWriter(new FileWriter(filePath.toFile()));
+        writer.write(dataString);
+        writer.close();
+
+        Service service = Service.FILE_PRIVATE;
+        assertTrue(service.isValidationRequired());
+
+        assertEquals(ValidationResult.OK, service.validate(filePath));
+    }
+
+    @Test
+    public void testEncryptedData() throws IOException {
+        String dataString = "qortalEncryptedDatabMx4fELNTV+ifJxmv4+GcuOIJOTo+3qAvbWKNY2L1rfla5UBoEcoxbtjgZ9G7FLPb8V/Qfr0bfKWfvMmN06U/pgUdLuv2mGL2V0D3qYd1011MUzGdNG1qERjaCDz8GAi63+KnHHjfMtPgYt6bcqjs4CNV+ZZ4dIt3xxHYyVEBNc=";
+
+        // Write the data a single file in a temp path
+        Path path = Files.createTempDirectory("testValidPrivateData");
+        Path filePath = Paths.get(path.toString(), "test");
+        filePath.toFile().deleteOnExit();
+
+        BufferedWriter writer = new BufferedWriter(new FileWriter(filePath.toFile()));
+        writer.write(dataString);
+        writer.close();
+
+        // Validate a private service
+        Service service = Service.FILE_PRIVATE;
+        assertTrue(service.isValidationRequired());
+        assertEquals(ValidationResult.OK, service.validate(filePath));
+
+        // Validate a regular service
+        service = Service.FILE;
+        assertTrue(service.isValidationRequired());
+        assertEquals(ValidationResult.DATA_ENCRYPTED, service.validate(filePath));
+    }
+
+    @Test
+    public void testPlainTextData() throws IOException {
+        String dataString = "plaintext";
+
+        // Write the data a single file in a temp path
+        Path path = Files.createTempDirectory("testInvalidPrivateData");
+        Path filePath = Paths.get(path.toString(), "test");
+        filePath.toFile().deleteOnExit();
+
+        BufferedWriter writer = new BufferedWriter(new FileWriter(filePath.toFile()));
+        writer.write(dataString);
+        writer.close();
+
+        // Validate a private service
+        Service service = Service.FILE_PRIVATE;
+        assertTrue(service.isValidationRequired());
+        assertEquals(ValidationResult.DATA_NOT_ENCRYPTED, service.validate(filePath));
+
+        // Validate a regular service
+        service = Service.FILE;
+        assertTrue(service.isValidationRequired());
+        assertEquals(ValidationResult.OK, service.validate(filePath));
+    }
+
 }
\ No newline at end of file