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One of the weaknesses of Ceasar is that an attacker knows the order of my alphabet, IE ABC...Z

If I scramble this, then are there enough permutations to ensure my resultant ciphertext cannot be brute forced. Does this then only leave me vulnerable to frequency analysis.

Adrian
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1 Answers1

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This is a monoalphabetic substitution cipher (with a mixed alphabet; in the first section of the article there is a paragraph about its security)

While the keyspace of this cipher is huge (relatively speaking for a classical cipher) with $26!\approx 2^{88.4}$ possible keys, it is still quite easy to break with frequency analysis.

Caesar is much worse of course, because you can simply try out all $26$ possible keys, and that is not possible for a simple substitution cipher (with arbitrary permutation).

Does this then only leave me vulnerable to frequency analysis.

Well, that statement is true. But "more than almost nothing" doesn't mean much.

tylo
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  • But you don't know the key, I've scrambled the 26 letters up. – Adrian Feb 27 '17 at 21:35
  • So? You still have just one letter being substituted with a single other letter. Which part don't you understand? – Maarten Bodewes Feb 27 '17 at 21:38
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    @Adrian The key isn't necessary. For example, copy and paste the following into an online solver such as quipqiup: zqu eqd'm dooe k poz mq eofszwm mjtn; asoguodfz kdkxzntn kxqdo tn nuaatftodm – r3mainer Feb 27 '17 at 21:52
  • So I put that into the online Solver and it solved it using Frequency analysis. Which is what my original question was about. – Adrian Feb 28 '17 at 02:22
  • So, my scrambled alphabet will be susceptable to Freq Anal. My next task is to address this weakness in my App. Thanks. – Adrian Feb 28 '17 at 02:37
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    @Adrian Classical ciphers are only toy exercises in today's world, you should never use that in an actual application. You can not fix all the issues with those, especially if you start with basically zero security (which all classical ciphers have from a modern point of view). – tylo Feb 28 '17 at 09:34
  • I understand their problems, this is an interesting programming exercise for me. – Adrian Feb 28 '17 at 13:46