[Cryptography] Summary: compression before encryption

[Ray Dillinger]

On 01/14/2015 02:38 PM, Jerry Leichter wrote:

> A number of people, of course, wrote in to point out that "didn't he realize that he was just XOR'ing the message with itself so that the result was always all 0's."
> 
> Others responded, pointing to the (April 1) date of the issue....
> 
>                                                         -- Jerry :-)

Oh, Jerry, you skipped the punch line!

Of course a uniform string of zeros is amenable to a VERY tight
encryption scheme - you can express it as a one-place number using
hexadecimal notation. It works out to nicely compressed numbers
in other bases as well, thanks to some interesting properties of
the Chinese Remainder Theorem with respect to a universal-
remainder property that applies to all nonnegative integers
smaller than the least prime...

				Bear :-)


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