A classical cipher in which the ciphertext is obtained by scrambling the letters of the plaintext.

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How to break a columnar transposition cipher?

I'm currently studying for a cryptography exam. I've been given ciphertext that has been encrypted by a columnar transposition cipher. I've been given no shift key length or key word, the only thing I ...
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Blowfish and DES small block size and maximum message size

Would the following affect the maximum message size limititaion of Blowfish and DES due their small 64 bit block size? Let's take Blowfish for example. You take a 256 bit Blowfish key, quickly ...
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Bit level permutation

Could anyone explain how secure is bit level permutation? What is the most serious threat against the security of this kind of cipher? Thank you