diff --git a/steam/core/crypto.py b/steam/core/crypto.py
index 3872a3d..2cb701b 100644
--- a/steam/core/crypto.py
+++ b/steam/core/crypto.py
@@ -1,3 +1,5 @@
+import sys
+from struct import pack
 from base64 import b64decode
 from Crypto import Random
 from Crypto.Cipher import PKCS1_OAEP, AES
@@ -12,11 +14,15 @@ gdTckPv+T1JzZsuVcNfFjrocejN1oWI0Rrtgt4Bo+hOneoo3S57G9F1fOpn5nsQ6
 """
 
 BS = AES.block_size
-pad = lambda s: s + (BS - len(s) % BS) * chr(BS - len(s) % BS)
-unpad = lambda s: s[0:-ord(s[-1])]
+pad = lambda s: s + (BS - len(s) % BS) * pack('B', BS - len(s) % BS)
 
+if sys.version_info < (3,):
+    unpad = lambda s: s[0:-ord(s[-1])]
+else:
+    unpad = lambda s: s[0:-s[-1]]
 
-def generate_session_key(hmac_secret=''):
+
+def generate_session_key(hmac_secret=b''):
     session_key = Random.new().read(32)
     cipher = PKCS1_OAEP.new(RSA.importKey(b64decode(public_key)))
     encrypted_session_key = cipher.encrypt(session_key + hmac_secret)
diff --git a/tests/test_core_crypto.py b/tests/test_core_crypto.py
index 6b7eae1..f46aac4 100644
--- a/tests/test_core_crypto.py
+++ b/tests/test_core_crypto.py
@@ -1,5 +1,6 @@
 import unittest
 import mock
+from binascii import hexlify
 
 from steam.core import crypto
 
@@ -8,7 +9,7 @@ class crypto_testcase(unittest.TestCase):
     def setUp(self):
         class NotRandom:
             def read(self, n):
-                return '1' * n
+                return b'1' * n
 
         def fakeNew():
             return NotRandom()
@@ -20,38 +21,38 @@ class crypto_testcase(unittest.TestCase):
         crypto.Random.new = self._oldnew
 
     def test_keygen(self):
-        expected_key = '1' * 32
-        expected_ekey = ('82a5d4d6de38e443ed3e6f0a1701a2c47bc98e0860e7883638ea5263a1744d02'
-                         'f733f09bc6b0f9b2a371bbb79b639208521f88658aab38c23e181d39a58ae39e'
-                         'c4e207fba822d523028d3c04e812abdc2247aa8d8e6e4a89c7a65671c5bcb329'
-                         '51c6d721ccf57cc2920d6ff3b69bfb2c611b1275badcd3e37fe024c9a25bf4b0'
+        expected_key = b'1' * 32
+        expected_ekey = (b'82a5d4d6de38e443ed3e6f0a1701a2c47bc98e0860e7883638ea5263a1744d02'
+                         b'f733f09bc6b0f9b2a371bbb79b639208521f88658aab38c23e181d39a58ae39e'
+                         b'c4e207fba822d523028d3c04e812abdc2247aa8d8e6e4a89c7a65671c5bcb329'
+                         b'51c6d721ccf57cc2920d6ff3b69bfb2c611b1275badcd3e37fe024c9a25bf4b0'
                          )
 
         key, ekey = crypto.generate_session_key()
-        ekey = ekey.encode('hex')
+        ekey = hexlify(ekey)
 
         self.assertEqual(key, expected_key)
         self.assertEqual(ekey, expected_ekey)
 
     def test_keygen_with_challenge(self):
-        expected_key = '1' * 32
-        expected_ekey = ('d710c55122f9bf772ec9c0f21d75c05055764d5445902577340029b4707e1725'
-                         'd61bec77f41b17faed6577d08c812cef76dca8b0b0b2329e1f33ea4cfa31f1e6'
-                         '0babc859c55b6ac94497b5dc9b0bc89629290dc038274af4377771e088e92887'
-                         '30d3906f6b698fd113ba36e3d28a5e1ce0283b27a1adda538df5dc5b179cf84f'
+        expected_key = b'1' * 32
+        expected_ekey = (b'd710c55122f9bf772ec9c0f21d75c05055764d5445902577340029b4707e1725'
+                         b'd61bec77f41b17faed6577d08c812cef76dca8b0b0b2329e1f33ea4cfa31f1e6'
+                         b'0babc859c55b6ac94497b5dc9b0bc89629290dc038274af4377771e088e92887'
+                         b'30d3906f6b698fd113ba36e3d28a5e1ce0283b27a1adda538df5dc5b179cf84f'
                          )
 
-        key, ekey = crypto.generate_session_key('5'*16)
-        ekey = ekey.encode('hex')
+        key, ekey = crypto.generate_session_key(b'5'*16)
+        ekey = hexlify(ekey)
 
         self.assertEqual(key, expected_key)
         self.assertEqual(ekey, expected_ekey)
 
 
     def test_encryption(self):
-        message = "My secret message"
-        key = '9' * 32
-        hmac = '3' * 16
+        message = b'My secret message'
+        key = b'9' * 32
+        hmac = b'3' * 16
 
         # legacy
         cyphertext = crypto.symmetric_encrypt(message, key)
@@ -67,6 +68,6 @@ class crypto_testcase(unittest.TestCase):
 
         # failing HMAC check
         with self.assertRaises(RuntimeError):
-            crypto.symmetric_decrypt_HMAC(cyphertext, key, '4'*16)
+            crypto.symmetric_decrypt_HMAC(cyphertext, key, b'4'*16)