UNBWTS vs BWT for pre-encryption pass
- From: biject <biject.bwts@xxxxxxxxx>
- Date: Tue, 22 Jul 2008 07:45:03 -0700 (PDT)
Take a simple key then repeatedly XOR it the length of a long text
file. This kind of encryption is what most beginners come up with as
a safe encryption however it is one of the easiest to brake if
underlying file plaintext English.
The question is does doing a BWT or UNBWT before this encryption
offer any extra protection assuming the attacker has only access to
what you did and the results. I am only looking at binary version of
BWTS and UNBWTS since that would be better but one could use the
ordinary 256 symbol BWTS.
The BWTS of long text file would create very long strings of zeros
and ones. This would cause the repeated key to likely be exposed in
the sequences of zeros as unchanged and inverted in a long series of
ones. Without to much difficulty one could test each sequence of
bits in ciphertext for either the inverted key or the actual key. If
none leads to correct key one could even test for the underlying
binary bwts to have ben 000...111.. or the opposite. The point is
that doing a BWTS as a stand alone for the encryption pass would
weaken this kind of encryption and would make it easier to bust than
What about doing a binay UNBWTS on text before an encryption pass.
Well there would not be long string of ones and zeros so the same kind
of brake is not possible.
Its seems as with compression on text or most useful files. A BWTS
make compression or breaking of encryption easier. While doing a
UNBWTS makes not only compression harder but the decryption of a
simple encryptor would be harder. Any comments welcome excpt those
flaming my english it sucks I already now that.
David A. Scott
My Crypto code
http://www.jim.com/jamesd/Kong/scott19u.zip old version
My Compression code http://bijective.dogma.net/
**TO EMAIL ME drop the roman "five" **
Disclaimer:I am in no way responsible for any of the statements
made in the above text. For all I know I might be drugged.
As a famous person once said "any cryptograhic
system is only as strong as its weakest link"
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