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But this increases the keys, you need to store these permutations. Is it a good idea? I wouldn't think so; not so much from a subkey storage perspective, but from a performance perspective. Storage could be do-able; $\log_2 128! \approx 716.16$; $20$ of these could be stored in $1791$ bytes, although it is likely that you wouldn't store them in a storage-...


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Oh, that one is simple: any key size is possible. The key size for RSA is set to the size of the modulus. The modulus in turn is the multiplication of two (or more) large primes. Of course, multiplication means that all prime sizes are added together (give or take a bit). However, not every implementation will allow any key size. Since computers are byte ...


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Appending the CRC to the data and then encrypting the whole block before sending will severely compromise the error detection capabilities of the CRC. In fact, a single bit error during transmission can cause you to decrypt a completely garbage message and still have a valid CRC check with a non-negligible probability. A CRC is designed to detect a small ...


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Is this cryptographic standard relevant for this kind of task? Yes to a degree, but with what's in the description (and assuming the CRC is checked after AES-CBC decryption) There is no protection against replay of earlier captured messages. The usual options to protect from replay are a two-way protocol where the receiver generates a nounce made part of ...


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