Cryptanalysis
Dale Harrison AEGIS
daleh at ix.netcom.com
Thu Jan 12 07:38:43 PST 1995
You wrote:
>If the encryption method is any good, the output will be pseudo-random
>with no digit being more frequent than any other. This certainly applies
>to IDEA and DES. With RSA, you usually have a random (IDEA) session key
>encrypted using the senders private key. This will also be an effectively
>'random' number.
Just a technical note, but a normal distribution of digits (i.e. 'no digit
more frequent than any other') is no inidication of either randomness or
'good' encryption. A better test is to look for a normal distribution at
all scale levels. For example, the following text block: "UUU" (in ASCII)
has a normal distribution at the bit level "0101 0101 0101 0101 0101 0101",
but not at the byte level.
Dale H.
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