message: leverage rust's possibility to view strings as bytes
diff: @@ -11,8 +11,8 @@ use std::iter::repeat;
  use hdwallet::{XPub};
  use cbor;
  -const NONCE : [u8;12] = [115,101,114,111,107,101,108,108,102,111,114,101]; // "serokellfore"
  -const SALT : [u8;15] = [97,100,100,114,101,115,115,45,104,97,115,104,105,110,103]; // "address-hashing"
  +const NONCE : &'static [u8] = b"serokellfore";
  +const SALT : &'static [u8] = b"address-hashing";
  const TAG_LEN : usize = 16;
  #[derive(Debug, PartialEq, Eq, PartialOrd, Ord, Clone)]
  