diff --git a/native/android/app/src/cpp/PlatformSpecificTools.cpp b/native/android/app/src/cpp/PlatformSpecificTools.cpp
--- a/native/android/app/src/cpp/PlatformSpecificTools.cpp
+++ b/native/android/app/src/cpp/PlatformSpecificTools.cpp
@@ -65,6 +65,13 @@
     return method(cls, backupID)->toStdString();
   }
 
+  static std::string getSIWEBackupMessagePath(std::string backupID) {
+    static const auto cls = javaClassStatic();
+    static auto method =
+        cls->getStaticMethod<JString(std::string)>("getSIWEBackupMessagePath");
+    return method(cls, backupID)->toStdString();
+  }
+
   static void removeBackupDirectory() {
     static const auto cls = javaClassStatic();
     static auto method = cls->getStaticMethod<void()>("removeBackupDirectory");
@@ -135,6 +142,15 @@
   return path;
 }
 
+std::string
+PlatformSpecificTools::getSIWEBackupMessagePath(std::string backupID) {
+  std::string path;
+  NativeAndroidAccessProvider::runTask([&path, backupID]() {
+    path = PlatformSpecificToolsJavaClass::getSIWEBackupMessagePath(backupID);
+  });
+  return path;
+}
+
 void PlatformSpecificTools::removeBackupDirectory() {
   NativeAndroidAccessProvider::runTask(
       []() { PlatformSpecificToolsJavaClass::removeBackupDirectory(); });
diff --git a/native/android/app/src/main/java/app/comm/android/fbjni/PlatformSpecificTools.java b/native/android/app/src/main/java/app/comm/android/fbjni/PlatformSpecificTools.java
--- a/native/android/app/src/main/java/app/comm/android/fbjni/PlatformSpecificTools.java
+++ b/native/android/app/src/main/java/app/comm/android/fbjni/PlatformSpecificTools.java
@@ -87,6 +87,12 @@
     return String.join(File.separator, backupDirPath, filename);
   }
 
+  public static String getSIWEBackupMessagePath(String backupID) {
+    String backupDirPath = PlatformSpecificTools.getBackupDirectoryPath();
+    String filename = String.join("-", "backup", backupID, "siweBackupMsg");
+    return String.join(File.separator, backupDirPath, filename);
+  }
+
   public static void removeBackupDirectory() {
     String backupDirPath = PlatformSpecificTools.getBackupDirectoryPath();
     try {
diff --git a/native/cpp/CommonCpp/Tools/PlatformSpecificTools.h b/native/cpp/CommonCpp/Tools/PlatformSpecificTools.h
--- a/native/cpp/CommonCpp/Tools/PlatformSpecificTools.h
+++ b/native/cpp/CommonCpp/Tools/PlatformSpecificTools.h
@@ -17,6 +17,7 @@
       std::string logID,
       bool isAttachments);
   static std::string getBackupUserKeysFilePath(std::string backupID);
+  static std::string getSIWEBackupMessagePath(std::string backupID);
   static void removeBackupDirectory();
 };
 
diff --git a/native/ios/Comm/PlatformSpecificTools.mm b/native/ios/Comm/PlatformSpecificTools.mm
--- a/native/ios/Comm/PlatformSpecificTools.mm
+++ b/native/ios/Comm/PlatformSpecificTools.mm
@@ -122,6 +122,16 @@
   return [[backupDir URLByAppendingPathComponent:filename].path UTF8String];
 }
 
+std::string
+PlatformSpecificTools::getSIWEBackupMessagePath(std::string backupID) {
+  NSURL *backupDir = getBackupDirAsURL();
+  NSString *backupIDObjC = [NSString stringWithCString:backupID.c_str()
+                                              encoding:NSUTF8StringEncoding];
+  NSString *filename = [@[ @"backup", backupIDObjC, @"siweBackupMsg" ]
+      componentsJoinedByString:@"-"];
+  return [[backupDir URLByAppendingPathComponent:filename].path UTF8String];
+}
+
 void PlatformSpecificTools::removeBackupDirectory() {
   NSURL *backupDir = getBackupDirAsURL();
   if (![NSFileManager.defaultManager fileExistsAtPath:backupDir.path]) {
diff --git a/native/native_rust_library/RustBackupExecutor.h b/native/native_rust_library/RustBackupExecutor.h
--- a/native/native_rust_library/RustBackupExecutor.h
+++ b/native/native_rust_library/RustBackupExecutor.h
@@ -9,6 +9,7 @@
 rust::String
 getBackupLogFilePath(rust::Str backupID, rust::Str logID, bool isAttachments);
 rust::String getBackupUserKeysFilePath(rust::Str backupID);
+rust::String getSIWEBackupMessagePath(rust::Str backupID);
 void createMainCompaction(rust::Str backupID, size_t futureID);
 void restoreFromMainCompaction(
     rust::Str mainCompactionPath,
diff --git a/native/native_rust_library/RustBackupExecutor.cpp b/native/native_rust_library/RustBackupExecutor.cpp
--- a/native/native_rust_library/RustBackupExecutor.cpp
+++ b/native/native_rust_library/RustBackupExecutor.cpp
@@ -26,6 +26,11 @@
       PlatformSpecificTools::getBackupUserKeysFilePath(std::string(backupID)));
 }
 
+rust::String getSIWEBackupMessagePath(rust::Str backupID) {
+  return rust::String(
+      PlatformSpecificTools::getSIWEBackupMessagePath(std::string(backupID)));
+}
+
 void createMainCompaction(rust::Str backupID, size_t futureID) {
   BackupOperationsExecutor::createMainCompaction(
       std::string(backupID), futureID);
diff --git a/native/native_rust_library/src/lib.rs b/native/native_rust_library/src/lib.rs
--- a/native/native_rust_library/src/lib.rs
+++ b/native/native_rust_library/src/lib.rs
@@ -401,6 +401,9 @@
     #[cxx_name = "getBackupUserKeysFilePath"]
     fn get_backup_user_keys_file_path(backup_id: &str) -> Result<String>;
 
+    #[cxx_name = "getSIWEBackupMessagePath"]
+    fn get_siwe_backup_message_path(backup_id: &str) -> Result<String>;
+
     #[cxx_name = "createMainCompaction"]
     fn create_main_compaction(backup_id: &str, future_id: usize);