diff --git a/Data/OTP.hs b/Data/OTP.hs
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--- /dev/null
+++ b/Data/OTP.hs
@@ -0,0 +1,39 @@
+-- |Implements HMAC-Based One-Time Password Algorithm as defined in RFC 4226 and
+-- Time-Based One-Time Password Algorithm as defined in RFC 6238.
+module Data.OTP (hotp, totp) where
+
+import Codec.Utils
+import Data.Bits
+import Data.HMAC
+import Data.Time.Clock
+import Data.Time.Clock.POSIX
+
+-- | Compute an HOTP using secret key and counter value.
+hotp
+    :: [Octet]  -- ^ Secret key
+    -> Int      -- ^ Counter value
+    -> Int      -- ^ Number of digits in password
+    -> Int      -- ^ HOTP
+hotp key count digit' = truncate_hotp (hmac_sha1 key count') digit'
+    where truncate_hotp hmac_result digit' = snum `mod` (10 ^ digit')
+            where snum  = fromTwosComp sbits
+                  sbits = dt hmac_result
+                  dt hmac_r = [(head p) .&. 0x7F] ++ (tail p)
+                      where offsetBits = (hmacr !! 19) .&. 0xF
+                            offset = fromTwosComp [offsetBits]
+                            p = take 4 (drop offset hmacr)
+                            hmacr = pad hmac_r
+                                where pad xs = if length xs < 20 then pad (0 : xs) else xs
+          count' = pad (toTwosComp count)
+              where pad xs = if length xs < 8 then pad (0 : xs) else xs
+
+-- | Compute an TOTP using secret key and time.
+totp
+    :: [Octet]  -- ^ Secret key
+    -> UTCTime  -- ^ Time
+    -> Int      -- ^ Number of digits in password
+    -> Int      -- ^ Period
+    -> Int      -- ^ TOTP
+totp key time digit' period = hotp key timeCounter digit'
+    where timePOSIX = utcTimeToPOSIXSeconds time
+          timeCounter = (floor timePOSIX) `div` period
diff --git a/LICENSE b/LICENSE
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--- /dev/null
+++ b/LICENSE
@@ -0,0 +1,18 @@
+Copyright (c) 2012 Artem Leshchev
+
+Permission is hereby granted, free of charge, to any person obtaining a copy
+of this software and associated documentation files (the "Software"), to deal
+in the Software without restriction, including without limitation the rights
+to use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies
+of the Software, and to permit persons to whom the Software is furnished
+to do so, subject to the following conditions:
+
+The above copyright notice and this permission notice shall be included
+in all copies or substantial portions of the Software.
+
+THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS
+FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR
+COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER
+IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR
+IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
diff --git a/OTP.cabal b/OTP.cabal
new file mode 100644
--- /dev/null
+++ b/OTP.cabal
@@ -0,0 +1,35 @@
+name:                OTP
+-- PVP summary:      +-+------- breaking API changes
+--                   | | +----- non-breaking API additions
+--                   | | | +--- code changes with no API change
+version:             0.0.0.1
+synopsis:            HMAC-Based and Time-Based One-Time Passwords
+description:         Implements HMAC-Based One-Time Password Algorithm as defined in RFC 4226 and Time-Based One-Time Password Algorithm as defined in RFC 6238.
+license:             MIT
+license-file:        LICENSE
+copyright:           (c) 2012 Artem Leshchev
+author:              Artem Leshchev
+maintainer:          matshch@gmail.com
+homepage:            https://github.com/matshch/OTP
+bug-reports:         https://github.com/matshch/OTP/issues
+category:            Cryptography
+build-type:          Simple
+cabal-version:       >=1.8
+
+library
+  exposed-modules:     Data.OTP
+  build-depends:       base >= 3 && < 5, Crypto >= 4, time >= 1.1
+
+Test-Suite tests
+    type:               exitcode-stdio-1.0
+    main-is:            Test/opt.hs
+    build-depends:      base >= 3 && < 5, Crypto >= 4, time >= 1.1
+
+source-repository head
+  type:     git
+  location: git://github.com/matshch/OTP.git
+
+source-repository this
+  type:     git
+  location: git://github.com/matshch/OTP.git
+  tag:      v0.0.0.1
diff --git a/Setup.hs b/Setup.hs
new file mode 100644
--- /dev/null
+++ b/Setup.hs
@@ -0,0 +1,2 @@
+import Distribution.Simple
+main = defaultMain
diff --git a/Test/opt.hs b/Test/opt.hs
new file mode 100644
--- /dev/null
+++ b/Test/opt.hs
@@ -0,0 +1,23 @@
+module Main where
+
+import Codec.Utils
+import Data.OTP
+import Data.Time
+import System.Exit (exitFailure)
+
+secret_otp :: [Octet]
+secret_otp = [49,50,51,52,53,54,55,56,57,48,49,50,51,52,53,54,55,56,57,48]
+
+hotp_t = zipWith (\x y -> (hotp secret_otp x 6) == y) [0..9]
+        [755224, 287082, 359152, 969429, 338314, 254676, 287922, 162583, 399871, 520489]
+
+totp_t = zipWith (\x y -> (totp secret_otp x 8 30) == y) (map (read) ["1970-01-01 00:00:59 UTC",
+        "2005-03-18 01:58:29 UTC", "2005-03-18 01:58:31 UTC", "2009-02-13 23:31:30 UTC",
+        "2033-05-18 03:33:20 UTC"])
+        [94287082, 07081804, 14050471, 89005924, 69279037]
+tests = hotp_t ++ totp_t
+
+main =  if (and tests) then putStrLn "Tests succeful!"
+        else do
+                putStrLn "Tests falls!"
+                exitFailure