Re: Confirmation of Shannon's Mistake about Perfect Secrecy of One-time-pad

On 11 5 , 10 38 , William Hughes <wpihug...@xxxxxxxxxxx> wrote:
On Nov 4, 9:33 pm, wangyong <hell...@xxxxxxx> wrote:





On 11 5 , 10 20 , William Hughes <wpihug...@xxxxxxxxxxx> wrote:

On Nov 4, 8:51 pm, wangyong <hell...@xxxxxxx> wrote:

On 11 5 , 9 36 , wangyong <hell...@xxxxxxx> wrote:

On 11 4 , 8 52 , William Hughes <wpihug...@xxxxxxxxxxx> wrote:

On Nov 4, 6:41 am, wangyong <hell...@xxxxxxx> wrote:

On 11 4 , 12 17 , David Bernier <david...@xxxxxxxxxxxx> wrote:

wangyong wrote:

[...]

In practice, when using OTP, the ciphertext can be anything.
If the ciphertext is fixed, something is going on to block
the ciphertexts that are different from the first
ciphertext. What mechanism does this?
===========the condition conflict and then compromise,just like the
four feet table In my paper.

What is the compromise? I don't understand.
Are you calculating a conditional probability?
Something like:
"Suppose event 'X' is observed. What is the chance that event 'Y' is
observed?"

David Bernier

We give a simple example of OPT to discuss the problem, plaintext
space is M {0,1}, ciphertext space is C {0,1} and key space is K
{0,1}. According to the information that cryptanalysts got
beforehand,
they can get the prior probability of plaintext as P(M=0) = 0.9 and
P(M=1) = 0.1. Later the ciphertext C=0 is intercepted. When only
considering C=0 and the cryptosystem (regardless of the prior

Note we are explicitely condidering a fixed cyphertext.

probability of plaintext), we can educe that the plaintexts are
equally likely, for there is a one-to-one correspondence between all
the plaintexts and keys for C=0.

However, the key probabilities are not equal for a fixed cyphertext so
the correxpondence tells you nothing about the probability
distribution
on the plaintext.

- William Hughes- -

- -

you admit the key is not equal, but you get the probability from equal
key.

The stinking point lies in you get the probability from the condition
c is not fixed.- -

- -

--------------------when c is fixed is considered, the probability of
k is not equal, as you have admit.
since that, how can you get the probability by the k is equal,
In that case, k and P is not independant,

If the cypertext is not fixed k and P are
independent.

For a fixed cyphertext k and P are not independent.
Trivially true.

- William Hughes- -

- -

if c is fixed,we ======do not =========have both
the key uniformly distributed and the plaintext not uniformly
distributed at the same time.

Correct. Because the key is not uniformly distributed.

I just think they are conflicting and need compromise

Since when c is fixed the key is not uniformly distributed there is no
problem.

- William Hughes- -

- -

Correct. Because the key is not uniformly distributed.


I just think they are conflicting and need compromise


Since when c is fixed the key is not uniformly distributed there is
no
problem.
=============yes,but you use the c is uniform to get the probability
distribution.
If not so, tell me how you get the 0.05,0.45-------when c is fixed.

.

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