diff --git a/native/cpp/CommonCpp/Tools/OlmUtils.h b/native/cpp/CommonCpp/Tools/OlmUtils.h
--- a/native/cpp/CommonCpp/Tools/OlmUtils.h
+++ b/native/cpp/CommonCpp/Tools/OlmUtils.h
@@ -12,4 +12,12 @@
  */
 std::string parseOLMPrekey(std::string prekeyBlob);
 
+/**
+ * Extracts the ed25519 signing public key from an identity keys JSON blob
+ * @param identityKeysBlob JSON string with identity keys
+ * @return The ed25519 public key string
+ * @throws std::runtime_error if parsing fails
+ */
+std::string getSigningPublicKey(const std::string &identityKeysBlob);
+
 } // namespace comm
diff --git a/native/cpp/CommonCpp/Tools/OlmUtils.cpp b/native/cpp/CommonCpp/Tools/OlmUtils.cpp
--- a/native/cpp/CommonCpp/Tools/OlmUtils.cpp
+++ b/native/cpp/CommonCpp/Tools/OlmUtils.cpp
@@ -33,4 +33,25 @@
   return parsedPrekey["curve25519"].values().begin()->asString();
 }
 
+std::string getSigningPublicKey(const std::string &identityKeysBlob) {
+  folly::dynamic parsedKeys;
+  try {
+    parsedKeys = folly::parseJson(identityKeysBlob);
+  } catch (const folly::json::parse_error &e) {
+    std::string errorMessage{
+        "parsing identity keys failed with: " + std::string(e.what())};
+    Logger::log(errorMessage);
+    throw std::runtime_error(errorMessage);
+  }
+
+  if (!parsedKeys.count("ed25519") || !parsedKeys["ed25519"].isString()) {
+    std::string errorMessage{
+        "parsing identity keys failed: ed25519 key missing or malformed"};
+    Logger::log(errorMessage);
+    throw std::runtime_error(errorMessage);
+  }
+
+  return parsedKeys["ed25519"].asString();
+}
+
 } // namespace comm