message: changed to reflect ietf implementation
diff: @@ -473,7 +473,7 @@ impl CryptoCommandExecutor {
  //structure protected and base64URL encode it
  let protected_struct = Protected {
  - enc: "xchacha20poly1305".to_string(),
  + enc: "xchacha20poly1305_ietf".to_string(),
  typ: "JWM/1.0".to_string(),
  alg: alg_val,
  recipients: encrypted_recipients_struct,
  