diff --git a/src/highlevelcrypto.py b/src/highlevelcrypto.py
index f89a31c8..82743acf 100644
--- a/src/highlevelcrypto.py
+++ b/src/highlevelcrypto.py
@@ -10,17 +10,22 @@ High level cryptographic functions based on `.pyelliptic` OpenSSL bindings.
 from binascii import hexlify
 
 import pyelliptic
-from bmconfigparser import BMConfigParser
 from pyelliptic import OpenSSL
 from pyelliptic import arithmetic as a
 
+from bmconfigparser import BMConfigParser
+
+__all__ = ['encrypt', 'makeCryptor', 'pointMult', 'privToPub', 'sign', 'verify']
+
 
 def makeCryptor(privkey):
     """Return a private `.pyelliptic.ECC` instance"""
     private_key = a.changebase(privkey, 16, 256, minlen=32)
     public_key = pointMult(private_key)
-    privkey_bin = '\x02\xca\x00\x20' + private_key
-    pubkey_bin = '\x02\xca\x00\x20' + public_key[1:-32] + '\x00\x20' + public_key[-32:]
+    privkey_bin = b'\x02\xca\x00\x20' + private_key
+    pubkey_bin = (
+        b'\x02\xca\x00\x20' + public_key[1:-32] + b'\x00\x20' + public_key[-32:]
+    )
     cryptor = pyelliptic.ECC(
         curve='secp256k1', privkey=privkey_bin, pubkey=pubkey_bin)
     return cryptor
@@ -29,7 +34,7 @@ def makeCryptor(privkey):
 def hexToPubkey(pubkey):
     """Convert a pubkey from hex to binary"""
     pubkey_raw = a.changebase(pubkey[2:], 16, 256, minlen=64)
-    pubkey_bin = '\x02\xca\x00 ' + pubkey_raw[:32] + '\x00 ' + pubkey_raw[32:]
+    pubkey_bin = b'\x02\xca\x00 ' + pubkey_raw[:32] + b'\x00 ' + pubkey_raw[32:]
     return pubkey_bin