prinet-proxy: Bugfix handling of decryption data length

src/main/pumpnet/prinet-proxy/main.c

@@ -34,7 +34,7 @@ static bool _transform_data_request(const struct pumpnet_prinet_proxy_packet* pa
         enc_data_len,
         dec_data->bytes);
 
-    if (dec_data_len != enc_data_len) {
+    if (dec_data_len < 0) {
         log_error("Decrypting data failed");
         return false;
     }

src/main/sec/prinet/prinet.c

@@ -83,7 +83,8 @@ size_t sec_prinet_decrypt(
         return -1;
     }
 
-    return enc_data_len;
+    // cut off the macbytes at the end of the message
+    return enc_data_len - crypto_box_MACBYTES;
 }
 
 size_t sec_prinet_encrypt(