diff --git a/Network/TLS/Extra/Certificate.hs b/Network/TLS/Extra/Certificate.hs
--- a/Network/TLS/Extra/Certificate.hs
+++ b/Network/TLS/Extra/Certificate.hs
@@ -10,6 +10,8 @@
 	( certificateVerifyChain
 	, certificateVerifyAgainst
 	, certificateVerifyDomain
+	, certificateVerifyValidity
+	, certificateFingerprint
 	) where
 
 import qualified Data.ByteString as B
@@ -26,6 +28,8 @@
 
 import Data.Certificate.X509Cert (oidCommonName)
 
+import Data.Time.Calendar
+
 #if defined(NOCERTVERIFY)
 
 # warning "********certificate verify chain doesn't yet work on your platform *************"
@@ -149,3 +153,13 @@
 		splitDot x  =
 			let (y, z) = break (== '.') x in
 			y : (if z == "" then [] else splitDot $ drop 1 z)
+
+-- Maybe should verify whole chain
+certificateVerifyValidity :: Day -> [X509] -> Bool
+certificateVerifyValidity _ []                         = False
+certificateVerifyValidity ctime (X509 cert _ _ _ _ :_) =
+	let ((beforeDay,_,_) , (afterDay,_,_)) = certValidity cert in
+	beforeDay < ctime && ctime <= afterDay
+
+certificateFingerprint :: (L.ByteString -> B.ByteString) -> X509 -> B.ByteString
+certificateFingerprint hash x509 = hash $ getSigningData x509
diff --git a/tls-extra.cabal b/tls-extra.cabal
--- a/tls-extra.cabal
+++ b/tls-extra.cabal
@@ -1,5 +1,5 @@
 Name:                tls-extra
-Version:             0.2.2
+Version:             0.2.3
 Description:
    a set of extra definitions, default values and helpers for tls.
 License:             BSD3
@@ -28,7 +28,7 @@
 
 Library
   Build-Depends:     base > 3 && < 5
-                   , tls >= 0.6.3 && < 0.7
+                   , tls >= 0.6.4 && < 0.7
                    , mtl
                    , network >= 2.3
                    , cryptohash >= 0.6
@@ -36,8 +36,9 @@
                    , vector
                    , crypto-api >= 0.5
                    , cryptocipher >= 0.2.5
-                   , certificate >= 0.8.1 && < 0.9
+                   , certificate >= 0.9 && < 1.0
                    , text >= 0.5 && < 1.0
+                   , time
   Exposed-modules:   Network.TLS.Extra
   other-modules:     Network.TLS.Extra.Certificate
                      Network.TLS.Extra.Cipher