Given a password as a seed for a Psuedo Random number generator and Fisher Yates Algorithm to shuffle bytes of a string to random places like Hello World to ldWoeHor ll, is it practically and/or theoretically impossible to break such cipher if plaintext contains enough words like >100?

Like for example, a string is shuffled and cipher generated is tca, if cryptanalysist tries to find dictionary words, he might get act or cat but he cannot be sure which one is right. Similarly bigger strings would have more such possibilities like trillions so it would be just too expensive to crack such cipher.

  • 2
    $\begingroup$ It doesn't matter how many words you have, you can still easily extract some information. For example: from the frequency of characters one can easily identify the language used by the text, probably even something more (e.g. I assume if you take medical research papers in English they might have a slightly different frequency spectrum than "normal" English so you might now that the "encrypted" text is a Medical research paper written in English). Modern ciphers employ both substitution & translation to be stronger. $\endgroup$
    – Bakuriu
    Commented Aug 26, 2023 at 13:30
  • $\begingroup$ You can also turn this around, and ask yourself if you cannot $\endgroup$
    – Maarten Bodewes
    Commented Aug 27, 2023 at 7:54
  • $\begingroup$ It also depends on what is meant by unbreakable. If you mean find the exact plaintext corresponding to the ciphertext, then it's probably somewhat difficult for large messages. But as @Bakuriu mentioned, you can still extract some information from the ciphertext. Furthermore, the encryption scheme is clearly not IND-CPA secure, which a property you want for most schemes. $\endgroup$ Commented Aug 29, 2023 at 8:29


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