Tue, 14 Jun 2016 19:00:52 GMT in alt.home.repair, wrote:
Rot13 has been used on online forums and usenet for years to hide
spoilers, demonstrate extremely 'weak' crypto, etc. It's like the
answers to the crossword puzzle being printed upside down somewhere
else on the page. It wasn't ever a UN*X only thing. Rot13 is a caeser
cipher that because of the specific shift number, is inversing. IE:
the same process used with no changes required will also decrypt
I'm not entirely sure what you mean by apparent distribution of
symbols. Do you mean you haven't seen/heard of any which (for
example) have the word frog to encrypt and begin writing the
encrypted data, say, in reverse? Or do you mean that the encrypted
message doesn't look like total garbage and things seem like you
could determine what they represent? IE: you see a pattern. One or
more symbols that may represent common letters?
If the latter, the Vigenere table does a very good job of eliminating
patterns if used with a proper key. The issue only comes up if you're
using a bad key. And by bad, one that's shorter than the message
being encrypted by it and it doesnt consist of random characters.
Instead, it's actually a word or a series of them,grouped together.
This will certainly cause issue with the encryption process in so far
as weakness to patterns, freq based attacks; including those
discovered by Kerckhoffs, Friedman, and, Kasiski.
Now, concerning the caeser shift cipher...You don't need a
significantly long message to crack a caeser shift cipher. A short
sentence is often enough. And, If you know how a single letter should
be deciphered, you then also know the shift amount (which is the real
key to that cipher) and can decrypt the rest of the message with
In other words, it looks like this (shift 5):
Plain - ABCDEFGHIJKLMNOPQRSTUVWXYZ
More about the Vigenere cipher:
An example of semi best practice encryption using the default offset
style Vigenere cipher:
NonEncrypted Text Src:
Encrypted text result:
The above short message is likely, not 'crackable' using any of the
attack methods known for the cipher. The key is random and is longer
than the message to be encrypted. Despite this, the key imho, could
be made stronger by using more letters and/or reducing the unintended
frequency of certain repeats too often. For the purposes of this
though, it's solid enough.
Although this is still using the original Vigenere cipher and not a
scrambled version (more on that below) due to details concerning the
key covered above, the encrypted material is immune to the attacks
created/devised by Friedman, Kasiski, and, Kerckhoffs. Kerckhoff had
another trick up his sleeve so if you want to ensure you stop his
attacks dead in their tracks, use the same principles as described
above, but, use a scrambled version of the cipher instead.
A scrambled Vigenere cipher doesn't use shifting as the original
does. Instead, each one of the 26 lines containing the alphabet has
them in a preferably completely random order. The idea is to stop the
shifting, as that makes the cipher potentially vulnerable to an
attack devised by Kerckhoffs.
The Friedman, Kasiski, and, Kerckhoffs tests can't reliably be used
for attack vectors when using the cipher modified as described above
with a good key! As they rely on frequency analysis, poorly chosen
keys, and stacked caeser cipher shifting.
MID: <nb7u27$crn$ email@example.com>
Hmmm. I most certainly don't understand how I can access a copy of a
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