Re: A twist on OTP for an outstandingly secure channel?



On 12 Jan 2007 11:08:58 -0800, "Jean-François Michaud"
<cometaj@xxxxxxxxxxx> wrote:

So, if I understand you correctly, you're basically saying that there's
no difference between having a whole sequential padded plaintext and
having sparse pseudo randomly positioned plaintext drowned in a sea of
bogus random data?

What's the reasoning behind this? I must say I don't see at all why
that would be the case.
Take the 40 byte cyphertext from your example:

@@@@@@@@@@
@@@@@@@@@@
@@@@@@@@@@
@@@@@@@@@@

Since this was encrypted with an OTP all possible plaintexts are
equally probable.

One of those possible plaintexts is your:

***e******
********l*
H*********
*****l****

Another of those possible plaintexts is my:

Hell100000
0000000000
0000000000
0000000000

Another possible plaintext is:

Bill100000
0000000000
0000000000
0000000000

Another possible plaintext is:

***i******
********l*
B*********
*****l****

Another possible plaintext is:

All your b
ases are b
elong to u
s.XXXXXXXX

and so on for all possible 2**320 possible plaintexts. The attacker
has no way of knowing which of the plaintexts is the correct one. All
the messages are equally secure since for each message there is a 1 in
2**320 chance of the attacker picking the right message.

rossum

.