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

On Oct 30, 8:41 am, wangyong <hell...@xxxxxxx> wrote:
On 10 30 , 7 32 , William Hughes <wpihug...@xxxxxxxxxxx> wrote:



On Oct 30, 2:07 am, wangyong <hell...@xxxxxxx> wrote:

Due to the mapping of M, K and C, the probabilities of M, K and C are
complicatedly interactional. For the above example, the probability
of
plaintext changes when the ciphertext is fixed, even though the
ciphertext is unknown.
When only considering the fixed ciphertext and the equiprobability of
key, ...

If the cyphertext is fixed then the key probablility is not uniform.
It is unknown (it depends both on the fixed value of the cyphertext,
and the probability distribution on the plaintext, neither
of which is known). The conclusion is not that the plaintext
probability
is uniform, but that the plaintext probability is unknown.

- William
Hughes

============================you should see the preconditions I set.you
are addlepated for you do not know there is a one-to-one
correspondence between all the plaintexts and keys, so the
probabilities of the corresponding plaintext and key are the same. As
all the keys are equally likely ...

No.

True: For a fixed plaintext the keys are equally likely.

False: For a fixed cyphertext the keys are equally likely.

For a fixed cyphertext the probability of the keys depends
on the probability of the plaintext, which is unknown. So for
a fixed cyphertext the probability distribution on the keys
is unknown.


-William Hughes

.

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