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The biggest reason is performance. Stream ciphers are generally faster than block ciphers and perform fewer operations. Stream ciphers only need to generate a pseudorandom output while block ciphers need to be pseudorandom permutations. So when you create a steam cipher out of a block cipher, you are doing a lot more work to get the same effect. To get an ...


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There are two answers, really depending on your specifications and how your generator will be evaluated. If all you need is to have a PRNG with statistically excellent random, but really don't care about predictability or cryptographic considerations, go for something simple like a Mersenne Twister. If you actually need some effective stream-cipher, look ...


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Synchronous stream cipher, or just stream cipher. In a synchronous stream cipher a stream of pseudo-random digits is generated independently of the plaintext and ciphertext messages, and then combined with the plaintext (to encrypt) or the ciphertext (to decrypt). In the most common form, binary digits are used (bits), and the keystream is combined with ...


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Yes, you can do that. Start by generating a random key and encrypting the data under that key. Now, you in turn encrypt that key with your password-derived key. The twist is that you include the already encrypted file in your PBKDF. So you generate a random key $k$ and then encapsulate it as $\mathcal{E}_{k'}(k)$, where $k' = H(PBKDF(\text{password}) \| ...


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I have looked at some attacks on RC4 and be curious if some of them can be applied to Spritz as well. Does anybody else has analysed Spritz so far? Or is it far too early for results against Spritz? No third party analysis. Probably way too early. (Even the paper you linked is unpublished.) The answer may of course change any time. From the ...


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To answer the question "why does a block cipher use a Mode of Operation", we need to first examine the question "what is a block cipher?" A block cipher is a keyed operation that converts a string of N bits to a string of N bits (where N is usually fixed by the block cipher; for AES, N=128), in a way that, without the key, looks like a random permutation, ...



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