Re: Chosen plaintext attacks

On Sat, 18 Sep 2010 13:06:19 -0700 (PDT), JT
<jonas.thornvall@xxxxxxxxxxx> wrote:

There is clearly something wrong with your logic, you can *NEVER*
recover the plaintext without the CSPRNG material.
This is cryptography. If a cryptosystem cannot resist a known
plaintext attack then it is useless.

For example, the Freedonian government uses its diplomatic cypher to
send a long encyphered message to its Ambassador in Ruritania. The
Ruritanian security service intercepts the cyphertext. The next day
the Freedonian Ambassador reads out a long statement declaring war.
The Ruritanians now have both the intercepted cyphertext and the known
plaintext. If the Freedonian cypher cannot withstand the resulting
attack then that cypher is useless.

You might also want to research the cryptographic history surrounding
the statement made by the Japanese Ambassador to Washington on the day
of Pearl Harbour.

It seems to me that you less about this subject than you think you do.



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