diff --git a/native/cpp/CommonCpp/CryptoTools/CryptoModule.h b/native/cpp/CommonCpp/CryptoTools/CryptoModule.h
--- a/native/cpp/CommonCpp/CryptoTools/CryptoModule.h
+++ b/native/cpp/CommonCpp/CryptoTools/CryptoModule.h
@@ -83,7 +83,7 @@
   std::string signMessage(const std::string &message);
   static void verifySignature(
       const std::string &publicKey,
-      const std::string &message,
+      const OlmBuffer &message,
       const std::string &signature);
   std::optional<std::string> validatePrekey();
 };
diff --git a/native/cpp/CommonCpp/CryptoTools/CryptoModule.cpp b/native/cpp/CommonCpp/CryptoTools/CryptoModule.cpp
--- a/native/cpp/CommonCpp/CryptoTools/CryptoModule.cpp
+++ b/native/cpp/CommonCpp/CryptoTools/CryptoModule.cpp
@@ -449,7 +449,7 @@
 
 void CryptoModule::verifySignature(
     const std::string &publicKey,
-    const std::string &message,
+    const OlmBuffer &message,
     const std::string &signature) {
   OlmBuffer utilityBuffer;
   utilityBuffer.resize(::olm_utility_size());
@@ -458,8 +458,8 @@
       olmUtility,
       (uint8_t *)publicKey.data(),
       publicKey.length(),
-      (uint8_t *)message.data(),
-      message.length(),
+      message.data(),
+      message.size(),
       (uint8_t *)signature.data(),
       signature.length());
   if (verificationResult == -1) {
@@ -470,7 +470,7 @@
 
 std::optional<std::string> CryptoModule::validatePrekey() {
   static const uint64_t maxPrekeyPublishTime = 30 * 24 * 60 * 60; // 30 days
-  static const uint64_t maxOldPrekeyAge = 24 * 60 * 60; // 24 hours
+  static const uint64_t maxOldPrekeyAge = 24 * 60 * 60;           // 24 hours
   std::optional<std::string> maybeNewPrekey;
 
   bool prekeyDoesntExist = this->prekeyDoesntExist();
diff --git a/native/cpp/CommonCpp/NativeModules/CommCoreModule.cpp b/native/cpp/CommonCpp/NativeModules/CommCoreModule.cpp
--- a/native/cpp/CommonCpp/NativeModules/CommCoreModule.cpp
+++ b/native/cpp/CommonCpp/NativeModules/CommCoreModule.cpp
@@ -2073,8 +2073,10 @@
         taskType job = [=, &innerRt]() {
           std::string error;
           try {
+            crypto::OlmBuffer messageBuffer(
+                messageStr.begin(), messageStr.end());
             crypto::CryptoModule::verifySignature(
-                keyStr, messageStr, signatureStr);
+                keyStr, messageBuffer, signatureStr);
           } catch (const std::exception &e) {
             error = "verifying signature failed with: " + std::string(e.what());
           }