Pure Python Data Mangling or Encrypting
Randall Smith
randall at tnr.cc
Sat Jun 27 14:17:09 EDT 2015
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
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