diff --git a/Data/Conduit/OpenPGP/Filter.hs b/Data/Conduit/OpenPGP/Filter.hs
--- a/Data/Conduit/OpenPGP/Filter.hs
+++ b/Data/Conduit/OpenPGP/Filter.hs
@@ -3,6 +3,8 @@
 -- This software is released under the terms of the Expat license.
 -- (See the LICENSE file).
 
+{-# LANGUAGE RecordWildCards #-}
+
 module Data.Conduit.OpenPGP.Filter (
    conduitFilter
  , FilterPredicates(..)
@@ -19,6 +21,7 @@
  , OVar(..)
  , OOp(..)
  , OValue(..)
+ , UPredicate(..)
 ) where
 
 import Control.Error.Util (hush)
@@ -27,17 +30,20 @@
 import Data.Conduit
 import qualified Data.Conduit.List as CL
 import Data.Maybe (fromMaybe)
+import Data.Serialize (runPut, put)
 
 import Codec.Encryption.OpenPGP.Fingerprint (eightOctetKeyID, fingerprint)
 import Codec.Encryption.OpenPGP.Internal (sigType, sigPKA, sigHA)
 import Codec.Encryption.OpenPGP.KeyInfo (pubkeySize)
 import Codec.Encryption.OpenPGP.Types
 
+{-# DEPRECATED PKPPredicate, SPPredicate, OPredicate "Use UPredicate instead" #-}
+
 data FilterPredicates = FilterPredicates {
     _pubKeyPktPredicate :: Expr PKPPredicate
   , _sigPktPredicate :: Expr SPPredicate
   , _otherPredicate :: Expr OPredicate
-}
+} | UnifiedFilterPredicate (Expr UPredicate)
 
 data Expr a = EAny
             | E a
@@ -104,23 +110,31 @@
 
 data OPredicate = OPredicate OVar OOp OValue
 
-data OVar = OVTag   -- ^ OpenPGP packet tag
+data OVar = OVTag    -- ^ OpenPGP packet tag
+          | OVLength -- ^ packet length (length of what, though?)
 
 data OValue = OInt Int
+            | OInteger Integer
     deriving Eq
 
 instance Ord OValue where
-    compare i j = compare (ovToInt i) (ovToInt j)
+    compare i j = compare (ovToInteger i) (ovToInteger j)
 
-ovToInt (OInt i) = i
+ovToInteger (OInt i) = fromIntegral i
+ovToInteger (OInteger i) = i
 
+data UPredicate = UPKPP PKPPredicate
+                | USPP SPPredicate
+                | UOP OPredicate
+
 conduitFilter :: Monad m => FilterPredicates -> Conduit Pkt m Pkt
 conduitFilter = CL.filter . superPredicate
 
 superPredicate :: FilterPredicates -> Pkt -> Bool
-superPredicate fp (PublicKeyPkt pkp) = eval pkpEval (_pubKeyPktPredicate fp) pkp
-superPredicate fp (SignaturePkt sp) = eval spEval (_sigPktPredicate fp) sp
-superPredicate fp p = eval oEval (_otherPredicate fp) p
+superPredicate fp@FilterPredicates{..} (PublicKeyPkt pkp) = eval pkpEval _pubKeyPktPredicate pkp
+superPredicate fp@FilterPredicates{..} (SignaturePkt sp) = eval spEval _sigPktPredicate sp
+superPredicate fp@FilterPredicates{..} p = eval oEval _otherPredicate p
+superPredicate (UnifiedFilterPredicate ufp) p = eval uEval ufp p
 
 pkpEval :: PKPPredicate -> PKPayload -> Bool
 pkpEval (PKPPredicate lhs o rhs) pkp = uncurry (opreduce o) (vreduce (lhs,pkp),rhs)
@@ -159,4 +173,11 @@
         opreduce OEquals = (==)
         opreduce OLessThan = (<)
         opreduce OGreaterThan = (>)
-        vreduce (OVTag, p) = OInt (fromIntegral (pktTag p))
+        vreduce (OVTag, p) = OInteger (fromIntegral (pktTag p))
+        vreduce (OVLength, p) = OInteger (fromIntegral (B.length (runPut $ put p)))  -- FIXME: this should be a length that makes sense
+
+uEval :: UPredicate -> Pkt -> Bool
+uEval (UPKPP pred) (PublicKeyPkt p) = pkpEval pred p
+uEval (USPP pred) (SignaturePkt s) = spEval pred s
+uEval (UOP pred) pkt = oEval pred pkt
+uEval _ _ = False  -- do not match packets of wrong type
diff --git a/hOpenPGP.cabal b/hOpenPGP.cabal
--- a/hOpenPGP.cabal
+++ b/hOpenPGP.cabal
@@ -1,5 +1,5 @@
 Name:                hOpenPGP
-Version:             1.6
+Version:             1.7
 Synopsis:            native Haskell implementation of OpenPGP (RFC4880)
 Description:         native Haskell implementation of OpenPGP (RFC4880)
 Homepage:            http://floss.scru.org/hOpenPGP/
@@ -255,4 +255,4 @@
 source-repository this
   type:     git
   location: git://git.debian.org/users/clint/hOpenPGP.git
-  tag:      v1.6
+  tag:      v1.7