python3 compatibility. speed up tests for travis

coldwallet/command_line.py

@@ -1,11 +1,12 @@
 from __future__ import absolute_import, division, print_function
 
 import argparse
+import sys
+
 import coldwallet
 import coldwallet.bitcoin
 import coldwallet.crypto
 import coldwallet.encoding
-import sys
 
 def main():
   parser = argparse.ArgumentParser()

coldwallet/crypto.py

@@ -5,8 +5,9 @@
 import base64
 import math
 import os
-import pylibscrypt
+
 import coldwallet.aes
+import pylibscrypt
 
 def disable_randomness():
   '''Make the random number generator produce deterministic (ie. non-random)
@@ -17,8 +18,13 @@ def disable_randomness():
   import sys
   sys.stderr.write('\n-- coldwallet running in test mode - random number generation disabled --\n\n')
   def fakerandom(b):
-    return "".join(chr(random.randrange(256)) for x in range(b))
-  random.seed(0)
+    # bytes/bytearray conversion and use and rounding of
+    # random.random() is required for Python2/3 compatibility.
+    return bytes(bytearray((int(round(random.random(), 10) * 256) for x in range(b))))
+  if sys.hexversion >= 0x03000000:
+    random.seed(a=0, version=1)
+  else:
+    random.seed(a=0)
   os.urandom = fakerandom
 
 def generate_random_string(bits):
@@ -33,35 +39,35 @@ def generate_random_string(bits):
   zero_padding = stringbytes * 8 - bits
   if zero_padding:
     mask = 0x100 - (2 ** zero_padding)
-    rand_string = rand_string[:-1] + chr(ord(rand_string[-1]) & mask)
+    rand_string = rand_string[:-1] + bytes(bytearray((ord(rand_string[-1:]) & mask,)))
 
   return rand_string
 
-def encrypt_secret_key(secret, coldkey, public_address):
+def encrypt_secret_key(secret, coldkey, public_address, scrypt_N=2**14, scrypt_p=1):
   '''Encrypt a secret exponent using an individual symmetric key. The symmetric
-     key is generated from the shared coldwallet key and the public bitcoin
-     address using the memory-hard scrypt hash. The result is returned in base64
-     encoding.
+     key is generated from the shared coldwallet key (given as byte string) and
+     the public bitcoin address (given in human readable format) using the
+     memory-hard scrypt hash. The result is returned in base64 encoding.
   '''
-  # Generate the symmetric key from the coldwallet key and the public bitcoin address
-  symmetric_key = pylibscrypt.scrypt(coldkey, public_address, N=2**15, p=3, olen=32)
+  # Generate a 256 bit symmetric key from the coldwallet key and the public bitcoin address
+  symmetric_key = pylibscrypt.scrypt(coldkey, public_address.encode('ascii'), olen=32, N=scrypt_N, p=scrypt_p)
 
   # Encrypt the secret exponent with the symmetric key
   encrypted_secret = coldwallet.aes.encrypt_block(secret, symmetric_key)
 
   # Base64 encode the result
-  return base64.b64encode(encrypted_secret)
+  return base64.b64encode(encrypted_secret).decode('ascii')
 
-def decrypt_secret_key(code, coldkey, public_address):
+def decrypt_secret_key(code, coldkey, public_address, scrypt_N=2**14, scrypt_p=1):
   '''Decrypt a secret exponent, given in base64 encoding, using an individual
      symmetric key. The symmetric key is generated as above. The result is
      returned as a byte string.
   '''
   # Base64 decode the input
-  code = base64.b64decode(code)
+  code = base64.b64decode(code.encode('ascii'))
 
-  # Generate the symmetric key from the coldwallet key and the public bitcoin address
-  symmetric_key = pylibscrypt.scrypt(coldkey, public_address, N=2**15, p=3, olen=32)
+  # Generate a 256 bit symmetric key from the coldwallet key and the public bitcoin address
+  symmetric_key = pylibscrypt.scrypt(coldkey, public_address.encode('ascii'), olen=32, N=scrypt_N, p=scrypt_p)
 
   # Decrypt the secret exponent with the symmetric key
   secret = coldwallet.aes.decrypt_block(code, symmetric_key)

tests/test_command_line.py

@@ -1,8 +1,9 @@
 from __future__ import absolute_import, division
 
-import pytest
 import sys
 
+import pytest
+
 def test_get_command_line_help(capsys):
   import coldwallet.command_line
   sys.argv = [ 'coldwallet', '--help' ]

tests/test_crypto.py

@@ -26,7 +26,7 @@ def test_random_string_generation():
   # If number of bits is not divisble by 8 then the remaining bits must be 0
   rand = coldwallet.crypto.generate_random_string(bits=36)
   assert len(rand) == 5
-  assert ord(rand[4]) & 0x0F == 0
+  assert bytearray(rand)[4] & 0x0F == 0
 
 def test_random_string_padding():
   import coldwallet.crypto
@@ -61,26 +61,29 @@ def test_encoding_and_decoding_secret_key():
   # Generate a coldwallet key
   coldkey = coldwallet.crypto.generate_random_string(bits=36*8)
 
+  # Use weaker scrypt parameter setting to speed up testing
+  N = 2**8 # default: 2**14
+
   # Encrypt one with the other
-  code = coldwallet.crypto.encrypt_secret_key(private_key, coldkey, public_address)
-  assert code == "I06olv7sBr0mZ0DOV5qR8edp1rLF2x+nolKlAV+/kOj8aGp4jAHW1VuTawB90+fU"
+  code = coldwallet.crypto.encrypt_secret_key(private_key, coldkey, public_address, scrypt_N=N)
+  assert code == "I06olv7sBr0mZ0DOV5qR8RyvXPWt8yGjFbuhlj1vDO+clw/KLpS3mhEerUyRKgft"
 
   # Encrypt one with the other again
-  code = coldwallet.crypto.encrypt_secret_key(private_key, coldkey, public_address)
+  code = coldwallet.crypto.encrypt_secret_key(private_key, coldkey, public_address, scrypt_N=N)
   # A new initialization vector is used, so the resulting code changes
-  assert code == "70vfOobHgodn7ICiLPWlbBgQKSc6X4c8ZUAalNq6URJ3UeNJJptdPEzbt4ceQMWs"
+  assert code == "70vfOobHgodn7ICiLPWlbPAlhoCCCt5enrC9fM/Ml0uyM7gqGuiGZPPyAa5kRpK4"
 
   # Decrypt the private key again
-  verify_key = coldwallet.crypto.decrypt_secret_key(code, coldkey, public_address)
+  verify_key = coldwallet.crypto.decrypt_secret_key(code, coldkey, public_address, scrypt_N=N)
   assert verify_key == private_key
 
   # Attempt decryption with wrong public address
   public_address = "3DR2Dp74CqtqXhU9MznV2r4qTuZBGYagP"
-  verify_key = coldwallet.crypto.decrypt_secret_key(code, coldkey, public_address)
+  verify_key = coldwallet.crypto.decrypt_secret_key(code, coldkey, public_address, scrypt_N=N)
   assert verify_key != private_key
 
   # Attempt decryption with wrong coldwallet key
   public_address = "1DR2Dp74CqtqXhU9MznV2r4qTuZBGYagP"
   coldkey = coldwallet.crypto.generate_random_string(bits=36*8)
-  verify_key = coldwallet.crypto.decrypt_secret_key(code, coldkey, public_address)
+  verify_key = coldwallet.crypto.decrypt_secret_key(code, coldkey, public_address, scrypt_N=N)
   assert verify_key != private_key