Support for traditional PKWARE encryption for Zip files in Python 2.7 & 3.4

Description

• Modified versions of /usr/lib64/python2.7/zipfile.py and /usr/lib64/python3.4/zipfile.py
• Python Software Foundation License applies
• Implemented for ZipFile.write() -- file operations
• Implemented for ZipFile.writestr() -- in-memory operations
• Encryption is active if password is set with ZipFile.setpassword()
• Default password is set to 'infected' for cli commands
• This implementation is probably not very good at handling large files
• WARNING (you already know this) This encryption scheme should not be used to protect sensitive information, it is known to be broken (see this paper).

Example usage

• Python 2.7 - in-memory operations

   ...
   # Initialize a new password protected zip file from an empty buffer
   zipfile_as_buffer = ''
   zipfile_as_stream = io.BytesIO(zipfile_as_buffer)
   zipfile_object = ZipFile(zipfile_as_stream, 'w', allowZip64=True)
   zipfile_object.setpassword("infected")
  
   # Define data to be archived
   data1 = "blabla"
   data1_as_stream = io.BytesIO(data1)
   data2 = "blibli"
   data2_as_stream = io.BytesIO(data2)
  
   # Deflate & add two file entries to the encrypted archive
   zipfile_object.writestr('bla', data1, compress_type=ZIP_DEFLATED)
   zipfile_object.writestr('bli', data2, compress_type=ZIP_DEFLATED)
   zipfile_object.close()
  
   # Do whatever you want with the resulting zip file
   zipfile_as_stream.seek(0)
   sys.stdout.write(zipfile_as_stream.read())
   ...

• Python 3.4 - in-memory operations

   ...
   # Initialize a new password protected zip file from an empty buffer
   zipfile_as_buffer = ''
   zipfile_as_stream = io.BytesIO(bytes(zipfile_as_buffer, "utf-8"))
   zipfile_object = ZipFile(zipfile_as_stream, 'w', allowZip64=True)
   zipfile_object.setpassword(bytes("infected", "utf-8"))
  
   # Define data to be archived
   data1 = "blabla"
   data1_as_stream = io.BytesIO(bytes(data1, "utf-8"))
   data2 = "blibli"
   data2_as_stream = io.BytesIO(bytes(data2, "utf-8"))
  
   # Deflate & add two file entries to the encrypted archive
   zipfile_object.writestr('bla', data1, compress_type=ZIP_DEFLATED)
   zipfile_object.writestr('bli', data2, compress_type=ZIP_DEFLATED)
   zipfile_object.close()
  
   # Do whatever you want with the resulting zip file
   zipfile_as_stream.seek(0)
   sys.stdout.buffer.write(zipfile_as_stream.read())
   ...