diff --git a/hoauth.cabal b/hoauth.cabal
--- a/hoauth.cabal
+++ b/hoauth.cabal
@@ -1,5 +1,5 @@
 name: hoauth
-version: 0.0.4
+version: 0.1.0
 category: Network,Protocol,OAuth
 license: BSD3
 license-file: LICENSE
@@ -10,15 +10,15 @@
 cabal-version: >= 1.6
 tested-with: GHC==6.8.2,GHC==6.10.4
 synopsis: A Haskell implementation of OAuth 1.0 protocol.
-description: This library implements both PLAINTEXT and HMAC-SHA1 signatures
-             as defined in the specification 1.0. Currently it supports only
-             /consumer/ related functions, but there are plans to add support
-             /service providers/ as well.
+description: This library implements all PLAINTEXT, HMAC-SHA1 and RSA-SHA1
+             signatures as defined in the specification 1.0. Currently it
+             supports only /consumer/ related functions, but there are plans to
+             add support /service providers/ as well.
 
              More info at: <http://oauth.net/>
 
 library
-  build-depends: base>=3&&<=4,bytestring,SHA,base64-string,utf8-string
+  build-depends: base>=3&&<=4,bytestring>=0.9.0.1,SHA>=1.4.0,RSA>=1.0.2,base64-string>=0.1,utf8-string>=0.3.3
   exposed-modules: Network.Protocol.OAuth.Consumer,Network.Protocol.OAuth.Request,Network.Protocol.OAuth.Signature
   hs-source-dirs: src/main/haskell
   ghc-options: -Wall -fwarn-tabs
@@ -28,7 +28,7 @@
   Default: False
 
 executable test_hoauth
-  build-depends: base>=3&&<=4,bytestring,SHA,base64-string,HUnit
+  build-depends: base>=3&&<=4,bytestring>=0.9.0.1,SHA>=1.4.0,RSA>=1.0.2,base64-string>=0.1,utf8-string>=0.3.3,HUnit>=1.2.0.0
   ghc-options: -fno-ignore-asserts -fwarn-tabs
   hs-source-dirs: src/main/haskell,src/test/haskell
   main-is: Tests.hs
diff --git a/src/main/haskell/Network/Protocol/OAuth/Consumer.hs b/src/main/haskell/Network/Protocol/OAuth/Consumer.hs
--- a/src/main/haskell/Network/Protocol/OAuth/Consumer.hs
+++ b/src/main/haskell/Network/Protocol/OAuth/Consumer.hs
@@ -27,7 +27,7 @@
 -- | A pure library that implements oauth authentication protocol as defined in <http://oauth.net/core/1.0a>.
 --
 -- Refer to <http://oauth.net/> for more information about the oauth protocol.
-module Network.Protocol.OAuth.Consumer (Token(),Consumer(..),request,response,oauth_token,oauth_token_secret,oauth_extra) where
+module Network.Protocol.OAuth.Consumer (Token(),Consumer(..),request,response,oauth_token,oauth_token_secret,oauth_extra,plaintext_signature,hmacsha1_signature) where
 
 import Network.Protocol.OAuth.Request as R
 import qualified Data.ByteString.Lazy as B
@@ -49,6 +49,16 @@
   | Authenticated String String Token
   deriving (Show,Read,Eq)
 
+-- | The PLAINTEXT signature for a given consumer
+plaintext_signature :: Consumer -> S.Method
+plaintext_signature (Authenticated _ s t) = S.PLAINTEXT s ((Just . oauth_token_secret) t)
+plaintext_signature (Unauthenticated _ s) = S.PLAINTEXT s Nothing
+
+-- | The HMAC-SHA1 signature for a given consumer 
+hmacsha1_signature :: Consumer -> S.Method
+hmacsha1_signature (Authenticated _ s t) = S.HMAC_SHA1 s ((Just . oauth_token_secret) t)
+hmacsha1_signature (Unauthenticated _ s) = S.HMAC_SHA1 s Nothing
+
 -- | Sign a request for oauth request. Use this either to sign requests with a proper Access token or to use the oauth protocol to get a token from service provider.
 --
 -- The request you provide /must/ contain /oauth_nonce/ and /oauth_timestamp/ parameters properly defined.
@@ -79,6 +89,6 @@
                                     >>| _sign csec tsec met
 
 _sign :: (S.Signer s,Show s) => String -> Maybe String -> s -> R.Request -> R.Request
-_sign csec tsec met req = let sig = S.sign met csec tsec req
+_sign csec tsec met req = let sig = S.sign met req
                           in req >>+ ("oauth_signature",Just sig)
 
diff --git a/src/main/haskell/Network/Protocol/OAuth/Signature.hs b/src/main/haskell/Network/Protocol/OAuth/Signature.hs
--- a/src/main/haskell/Network/Protocol/OAuth/Signature.hs
+++ b/src/main/haskell/Network/Protocol/OAuth/Signature.hs
@@ -33,6 +33,7 @@
 import qualified Data.ByteString.Lazy as B
 import qualified Data.ByteString.Lazy.Char8 as B1
 import qualified Codec.Binary.Base64.String as B2
+import qualified Codec.Crypto.RSA as R1
 
 -- | The signature method which will be used to sign requests.
 data Method =   
@@ -40,7 +41,8 @@
         SHOULD only be used over a secure channel such as /HTTPS/. It does
         not use the Signature Base String.
     -}
-    PLAINTEXT 
+    PLAINTEXT String         -- ^ The consumer secret
+              (Maybe String) -- ^ The token secret
     {-| The 'HMAC_SHA1' signature method uses the /HMAC-SHA1/ signature
         algorithm as defined in <http://tools.ietf.org/html/rfc2104> where
         the Signature Base String is the text and the key is the
@@ -48,8 +50,15 @@
         the Consumer Secret and Token Secret, separated by an /&/ character
         (ASCII code 38) even if empty.
     -}
-  | HMAC_SHA1 
-  deriving (Eq)
+  | HMAC_SHA1 String         -- ^ The consumer secret
+              (Maybe String) -- ^ The token secret
+    {-| The RSA-SHA1 signature method uses the RSASSA-PKCS1-v1_5 signature
+        algorithm as defined in [RFC3447] section 8.2 (more simply known as
+        PKCS#1), using SHA-1 as the hash function for EMSA-PKCS1-v1_5. It is
+        assumed that the Consumer has provided its RSA public key in a verified
+        way to the Service Provider.
+    -}
+  | RSA_SHA1 R1.PrivateKey
 
 -- | Functions to sign requests according oauth spec.
 class Signer a where
@@ -58,28 +67,26 @@
       at <http://oauth.net/core/1.0a#signing_process>.
   -}
   sign :: a                -- ^ The signature method to use
-          -> String        -- ^ The consumer secret
-          -> Maybe String  -- ^ The token secret
           -> R.Request 
           -> String        -- ^ The signature
 
 instance Signer Method where
-  sign PLAINTEXT k (Just s) _ = k ++ "&" ++ s
-  sign PLAINTEXT k Nothing  _ = k ++ "&"
+  sign (PLAINTEXT k (Just s)) _ = k ++ "&" ++ s
+  sign (PLAINTEXT k Nothing)  _ = k ++ "&"
 
-  sign HMAC_SHA1 k Nothing  r = let secret = B.concat [R.encodes k, _froms "&"]
-                                in (B2.encode . B1.unpack . S.bytestringDigest . S.hmacSha1 secret . _basestr) r
-  sign HMAC_SHA1 k (Just s) r = let secret = B.concat [R.encodes k, _froms "&", R.encodes s]
-                                in (B2.encode . B1.unpack . S.bytestringDigest . S.hmacSha1 secret . _basestr) r
+  sign (HMAC_SHA1 k Nothing)  r = let secret = B.concat [R.encodes k, _froms "&"]
+                                  in (B2.encode . B1.unpack . S.bytestringDigest . S.hmacSha1 secret . _basestr) r
+  sign (HMAC_SHA1 k (Just s)) r = let secret = B.concat [R.encodes k, _froms "&", R.encodes s]
+                                  in (B2.encode . B1.unpack . S.bytestringDigest . S.hmacSha1 secret . _basestr) r
 
+  sign (RSA_SHA1 k) r           = (B2.encode . B1.unpack . R1.rsassa_pkcs1_v1_5_sign R1.ha_SHA1 k . _basestr) r
+
 instance Show Method where
-  showsPrec _ PLAINTEXT = showString "PLAINTEXT"
-  showsPrec _ HMAC_SHA1 = showString "HMAC-SHA1"
+  showsPrec _ (PLAINTEXT _ _) = showString "PLAINTEXT"
 
-instance Read Method where
-  readsPrec _ ('P':'L':'A':'I':'N':'T':'E':'X':'T':r) = (PLAINTEXT,r) : []
-  readsPrec _ ('H':'M':'A':'C':'-':'S':'H':'A':'1':r) = (HMAC_SHA1,r) : []
-  readsPrec _ _                                       = []
+  showsPrec _ (HMAC_SHA1 _ _) = showString "HMAC-SHA1"
+
+  showsPrec _ (RSA_SHA1 _)    = showString "RSA-SHA1"
 
 _basestr :: R.Request -> B.ByteString
 _basestr r = let endpoint' = (R.encodes . _endpoint) r