old_contents: #!/usr/bin/env python2 
  # Copyright (c) 2015-2016 The Bitcoin Core developers
  # Distributed under the MIT software license, see the accompanying 
  # file COPYING or http://www.opensource.org/licenses/mit-license.php.
  
  import hashlib
  import sys
  import os
  from random import SystemRandom
  import base64
  import hmac
  
  if len(sys.argv) < 2:
      sys.stderr.write('Please include username as an argument.\n')
      sys.exit(0)
  
  username = sys.argv[1]
  
  #This uses os.urandom() underneath
  cryptogen = SystemRandom()
  
  #Create 16 byte hex salt
  salt_sequence = [cryptogen.randrange(256) for i in range(16)]
  hexseq = list(map(hex, salt_sequence))
  salt = "".join([x[2:] for x in hexseq])
  
  #Create 32 byte b64 password
  password = base64.urlsafe_b64encode(os.urandom(32))
  
  digestmod = hashlib.sha256
  
  if sys.version_info.major >= 3:
      password = password.decode('utf-8')
      digestmod = 'SHA256'
   
  m = hmac.new(bytearray(salt, 'utf-8'), bytearray(password, 'utf-8'), digestmod)
  result = m.hexdigest()
  
  print("String to be appended to chaincoin.conf:")
  print("rpcauth="+username+":"+salt+"$"+result)
  print("Your password:\n"+password)
  
new_contents: #!/usr/bin/env python
  # Copyright (c) 2015-2016 The Bitcoin Core developers
  # Distributed under the MIT software license, see the accompanying 
  # file COPYING or http://www.opensource.org/licenses/mit-license.php.
  
  import hashlib
  import sys
  import os
  from random import SystemRandom
  import base64
  import hmac
  
  if len(sys.argv) < 2:
      sys.stderr.write('Please include username as an argument.\n')
      sys.exit(0)
  
  username = sys.argv[1]
  
  #This uses os.urandom() underneath
  cryptogen = SystemRandom()
  
  #Create 16 byte hex salt
  salt_sequence = [cryptogen.randrange(256) for i in range(16)]
  hexseq = list(map(hex, salt_sequence))
  salt = "".join([x[2:] for x in hexseq])
  
  #Create 32 byte b64 password
  password = base64.urlsafe_b64encode(os.urandom(32))
  
  digestmod = hashlib.sha256
  
  if sys.version_info.major >= 3:
      password = password.decode('utf-8')
      digestmod = 'SHA256'
   
  m = hmac.new(bytearray(salt, 'utf-8'), bytearray(password, 'utf-8'), digestmod)
  result = m.hexdigest()
  
  print("String to be appended to chaincoin.conf:")
  print("rpcauth="+username+":"+salt+"$"+result)
  print("Your password:\n"+password)
  
subject: Use 'python' not 'python2'