Fingerprint.hs

   1 -- This file is part of htalkat
   2 -- Copyright (C) 2021 Martin Bays <mbays@sdf.org>
   3 --
   4 -- This program is free software: you can redistribute it and/or modify
   5 -- it under the terms of version 3 of the GNU General Public License as
   6 -- published by the Free Software Foundation, or any later version.
   7 --
   8 -- You should have received a copy of the GNU General Public License
   9 -- along with this program.  If not, see http://www.gnu.org/licenses/.
  10
  11 {-# LANGUAGE Safe #-}
  12
  13 module Fingerprint where
  14
  15 import           Control.Monad   (guard)
  16
  17 import qualified Data.ByteString as BS
  18
  19 import           HexString
  20
  21 -- | 16-byte SHA256/128 fingerprint
  22 newtype Fingerprint = Fingerprint BS.ByteString
  23     deriving (Eq,Ord,Show)
  24
  25 parseFingerprint :: String -> Maybe Fingerprint
  26 parseFingerprint s = do
  27     guard $ length s == 32
  28     Fingerprint <$> parseHexString s
  29
  30 showFingerprint :: Fingerprint -> String
  31 showFingerprint (Fingerprint fp) = showHexString fp