title: python "RSA key format is not supported" when reading from .pem file
body: <p>Here is my code:</p>
  
  <pre><code>from Crypto.PublicKey import RSA
  
  #Write key to file
  key = RSA.generate(4096)
  privateKey = key.exportKey()
  file1 = open('keyfile.pem', 'wb')
  file1.write(privateKey)
  file1.close()
  
  #Read key from file
  file2 = open('keyfile.pem', 'rb')
  key = RSA.importKey(file2.read()) #this is the problem
  </code></pre>
  
  <p>The error is "RSA key format is not supported." Can anyone help me with the best way to write/read the private key from a file?</p>