Pure Python Data Mangling or Encrypting

[Randall Smith]

On 06/27/2015 03:29 AM, Peter Otten wrote:


> Would it be sufficient to prepend the chunk with one block, say, of random
> data? To unmangle you'd just strip off that block.
>
> BLOCK = os.urandom(BLOCKSIZE)
>
> def mangle(source, dest):
>      dest.write(BLOCK)
>      shutil.copyfileobj(source, dest)
>
> def unmangle(source, dest):
>      source.read(BLOCKSIZE)
>      shutil.copyfileobj(source, dest)
>
> Disclaimer: I did not follow the ongoing discussion.
>

That is happening as a side effect.  Though not completely random, after 
running the data through a translation table, the 256 byte table is 
prepended.  Then a 4 byte checksum is calculated and prepended.

-Randall