diff --git a/src/tools.cpp b/src/tools.cpp
index a123280..e889274 100644
--- a/src/tools.cpp
+++ b/src/tools.cpp
@@ -796,12 +796,17 @@ namespace xmreg
 
         const size_t prefix_size = sizeof(chacha8_iv)
                                    + (authenticated ? sizeof(crypto::signature) : 0);
+        if (ciphertext.size() < prefix_size)
+        {
+            cerr <<  "Unexpected ciphertext size" << endl;
+            return {};
+        }
 
         crypto::chacha8_key key;
-
         crypto::generate_chacha8_key(&skey, sizeof(skey), key);
 
         const crypto::chacha8_iv &iv = *(const crypto::chacha8_iv*)&ciphertext[0];
+
         std::string plaintext;
 
         plaintext.resize(ciphertext.size() - prefix_size);
@@ -813,6 +818,11 @@ namespace xmreg
             crypto::public_key pkey;
             crypto::secret_key_to_public_key(skey, pkey);
 
+            const crypto::signature &signature =
+                    *(const crypto::signature*)&ciphertext[ciphertext.size()
+                                                           - sizeof(crypto::signature)];
+
+
             const crypto::signature &signature =
                     *(const crypto::signature*)&ciphertext[ciphertext.size()
                                                            - sizeof(crypto::signature)];