1 files changed, 21 insertions, 16 deletions

diff --git a/Data/OpenPGP/Util/Fingerprint.hs b/Data/OpenPGP/Util/Fingerprint.hs
index 20b6e72..b2e3904 100644
--- a/Data/OpenPGP/Util/Fingerprint.hs
+++ b/Data/OpenPGP/Util/Fingerprint.hs
@@ -1,5 +1,5 @@
 {-# LANGUAGE CPP #-}
-module Data.OpenPGP.Util.Fingerprint (fingerprint) where
+module Data.OpenPGP.Util.Fingerprint (fingerprint,Fingerprint(..)) where
 
 import qualified Data.OpenPGP as OpenPGP
 import qualified Data.ByteString as BS
@@ -17,12 +17,29 @@ import Crypto.Hash.MD5 as MD5
 import Crypto.Hash.SHA1 as SHA1
 #endif
 
+oo :: (b -> c) -> (a -> a1 -> b) -> a -> a1 -> c
+oo = (.) . (.)
+
+newtype Fingerprint = Fingerprint BS.ByteString
+
+instance Show Fingerprint where
+ show (Fingerprint bs) = hexify bs
+  where
+    hexify = map toUpper . hexString . BS.unpack
+
+    hexString :: [Word8] -> String
+    hexString = foldr (pad `oo` showHex) ""
+        where
+        pad s | odd $ length s = '0':s
+              | otherwise = s
+
+
 -- | Generate a key fingerprint from a PublicKeyPacket or SecretKeyPacket
 -- <http://tools.ietf.org/html/rfc4880#section-12.2>
-fingerprint :: OpenPGP.Packet -> String
+fingerprint :: OpenPGP.Packet -> Fingerprint
 fingerprint p
-    | OpenPGP.version p == 4 = hexify $ sha1 material
-    | OpenPGP.version p `elem` [2, 3] = hexify $ md5 material
+    | OpenPGP.version p == 4 = Fingerprint $ sha1 material
+    | OpenPGP.version p `elem` [2, 3] = Fingerprint $ md5 material
     | otherwise = error "Unsupported Packet version or type in fingerprint"
     where
 
@@ -35,15 +52,3 @@ fingerprint p
 #endif
 
     material = LZ.concat $ OpenPGP.fingerprint_material p
-
-    hexify = map toUpper . hexString . BS.unpack
-
-    hexString :: [Word8] -> String
-    hexString = foldr (pad `oo` showHex) ""
-        where
-        pad s | odd $ length s = '0':s
-              | otherwise = s
-
-    oo :: (b -> c) -> (a -> a1 -> b) -> a -> a1 -> c
-    oo = (.) . (.)
-