[bug] content of the op_return wasn't correctly serialized

src/silentpayments.rs

@@ -4,6 +4,7 @@ use std::str::FromStr;
 use anyhow::{Error, Result};
 
 use rand::{thread_rng, Rng, RngCore};
+use sp_client::bitcoin::hex::FromHex;
 use sp_client::bitcoin::psbt::raw;
 use sp_client::bitcoin::{Psbt, Transaction};
 use sp_client::bitcoin::{Amount, OutPoint};
@@ -149,10 +150,12 @@ pub fn create_transaction_for_address_with_shared_secret(
         return Err(Error::msg("Not enough available funds"));
     }
 
+    let message_bin = if message.is_some() { Vec::from_hex(message.unwrap())? } else { vec![] };
+
     let mut new_psbt = sp_wallet.get_client().create_new_psbt(
         inputs,
         vec![recipient],
-        message.map(|m| m.as_bytes()),
+        if !message_bin.is_empty() { Some(&message_bin) } else { None },
     )?;
 
     let change_addr = sp_wallet.get_client().sp_receiver.get_change_address();