diff --git a/eopayment/paybox.py b/eopayment/paybox.py
index 15ea18e..4333173 100644
--- a/eopayment/paybox.py
+++ b/eopayment/paybox.py
@@ -1,5 +1,6 @@
 # -*- coding: utf-8
 
+import codecs
 from collections import OrderedDict
 import datetime
 import logging
@@ -10,6 +11,7 @@ from Crypto.Signature import PKCS1_v1_5
 from Crypto.PublicKey import RSA
 from Crypto.Hash import SHA
 
+import six
 from six.moves.urllib import parse as urlparse
 from six.moves.urllib import parse as urllib
 
@@ -19,7 +21,7 @@ import string
 import warnings
 
 from .common import (PaymentCommon, PaymentResponse, FORM, PAID, ERROR, Form,
-        ORDERID_TRANSACTION_SEPARATOR, ResponseError)
+        ORDERID_TRANSACTION_SEPARATOR, ResponseError, force_text)
 
 __all__ = ['sign', 'Payment']
 
@@ -111,9 +113,10 @@ def sign(data, key):
             algo = ALGOS[v]
             break
     assert algo, 'Missing or invalid PBX_HASH'
-    tosign = ['%s=%s' % (k, unicode(v).encode('utf-8')) for k, v in data]
+    tosign = ['%s=%s' % (k, force_text(v)) for k, v in data]
     tosign = '&'.join(tosign)
     logger.debug('signed string %r', tosign)
+    tosign = tosign.encode('utf-8')
     signature = hmac.new(key, tosign, algo)
     return tuple(data) + (('PBX_HMAC', signature.hexdigest().upper()),)
 
@@ -210,22 +213,22 @@ class Payment(PaymentCommon):
 
     def request(self, amount, email, name=None, orderid=None, **kwargs):
         d = OrderedDict()
-        d['PBX_SITE'] = unicode(self.site)
-        d['PBX_RANG'] = unicode(self.rang).strip()[-2:]
-        d['PBX_IDENTIFIANT'] = unicode(self.identifiant)
+        d['PBX_SITE'] = force_text(self.site)
+        d['PBX_RANG'] = force_text(self.rang).strip()[-2:]
+        d['PBX_IDENTIFIANT'] = force_text(self.identifiant)
         d['PBX_TOTAL'] = (amount * Decimal(100)).to_integral_value(ROUND_DOWN)
-        d['PBX_DEVISE'] = unicode(self.devise)
+        d['PBX_DEVISE'] = force_text(self.devise)
         transaction_id = kwargs.get('transaction_id') or \
             self.transaction_id(12, string.digits, 'paybox', self.site,
                                 self.rang, self.identifiant)
-        d['PBX_CMD'] = unicode(transaction_id)
+        d['PBX_CMD'] = force_text(transaction_id)
         # prepend order id command reference
         if orderid:
             d['PBX_CMD'] = orderid + ORDERID_TRANSACTION_SEPARATOR + d['PBX_CMD']
-        d['PBX_PORTEUR'] = unicode(email)
+        d['PBX_PORTEUR'] = force_text(email)
         d['PBX_RETOUR'] = 'montant:M;reference:R;code_autorisation:A;erreur:E;signature:K'
         d['PBX_HASH'] = 'SHA512'
-        d['PBX_TIME'] = kwargs.get('time') or (unicode(datetime.datetime.utcnow().isoformat('T')).split('.')[0]+'+00:00')
+        d['PBX_TIME'] = kwargs.get('time') or (force_text(datetime.datetime.utcnow().isoformat('T')).split('.')[0]+'+00:00')
         d['PBX_ARCHIVAGE'] = transaction_id
         if self.normal_return_url:
             d['PBX_EFFECTUE'] = self.normal_return_url
@@ -238,16 +241,21 @@ class Payment(PaymentCommon):
                           "use automatic_return_url", DeprecationWarning)
             automatic_return_url = self.callback
         if automatic_return_url:
-            d['PBX_REPONDRE_A'] = unicode(automatic_return_url)
+            d['PBX_REPONDRE_A'] = force_text(automatic_return_url)
         d = d.items()
-        d = sign(d, self.shared_secret.decode('hex'))
+
+        if six.PY3:
+            shared_secret = codecs.decode(bytes(self.shared_secret, 'ascii'), 'hex')
+        else:
+            shared_secret = codecs.decode(bytes(self.shared_secret), 'hex')
+        d = sign(d, shared_secret)
         url = URLS[self.platform]
         fields = []
         for k, v in d:
             fields.append({
                 'type': u'hidden',
-                'name': unicode(k),
-                'value': unicode(v),
+                'name': force_text(k),
+                'value': force_text(v),
             })
         form = Form(url, 'POST', fields, submit_name=None,
                     submit_value=u'Envoyer', encoding='utf-8')
diff --git a/tests/test_paybox.py b/tests/test_paybox.py
index 2e9156b..bedcb69 100644
--- a/tests/test_paybox.py
+++ b/tests/test_paybox.py
@@ -1,5 +1,6 @@
 # -*- coding: utf-8 -*-
 
+import codecs
 from unittest import TestCase
 from decimal import Decimal
 import base64
@@ -19,7 +20,8 @@ BACKEND_PARAMS = {
 
 class PayboxTests(TestCase):
     def test_sign(self):
-        key = '0123456789ABCDEF0123456789ABCDEF0123456789ABCDEF0123456789ABCDEF0123456789ABCDEF0123456789ABCDEF0123456789ABCDEF0123456789ABCDEF'.decode('hex')
+        key = b'0123456789ABCDEF0123456789ABCDEF0123456789ABCDEF0123456789ABCDEF0123456789ABCDEF0123456789ABCDEF0123456789ABCDEF0123456789ABCDEF'
+        key = codecs.decode(key, 'hex')
         d = dict(paybox.sign([
                     ['PBX_SITE', u'12345678'],
                     ['PBX_RANG', u'32'],
@@ -97,7 +99,7 @@ UX4D2A/QcMvkEcRVXFx5tQqcE9/JnMqE41TF/ebn7jC/MBxxtPFkUN7+EZoeMN7x
 OWzAMDm/xsCWRvvel4GGixgm3aQRUPyTrlm4Ksy32Ya0rNnEDMAvB3dxOn7cp8GR
 ZdzrudBlevZXpr6iYwIDAQAB
 -----END PUBLIC KEY-----'''
-        data = 'coin\n'
+        data = b'coin\n'
         sig64 = '''VCt3sgT0ecacmDEWWNVXJ+jGmIPBMApK42tBJV0FlDjpllOGPy8MsAmLW4/QjTtx
 z0Dkz0NjxvU+5WzQZh9Uuxr/egRCwV4NMRWqu0zaVVioeBvl4/5CWm4f4/1L9+0m
 FBFKOZhgBJnkC+l6+XhT4aYWKaQ4ocmOMV92yjeXTE4='''