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Compared to fixed rotations, data-dependent rotations improve resistance to differential and linear cryptanalysis. A fixed rotation has no effect (beyond helping with diffusion) in the probability of a (xor-)differential characteristic, whereas a data-dependent rotation also introduces differences in the rotation amounts, which brings probabilities down. ...


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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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You are correct about extending number of rounds. It is safe to increase number of rounds. In most cases it will increase safety margin. Removing constants doesn't seem to be a good idea to me, as Salsa20 and ChaCha don't have any round constants. Purpose of constants is also to reduce number of bits that can be controlled by attacker, however key is not ...


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Although I do not have a formal proof I think a compressing encryption algorithm could not be secure. The reason is that we know there is no way to compress every input (information theoretically this is impossible). That means that a lossless compression algorithm can really only compress certain input strings. That in turn means that if our encryption ...


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Say you have the value $n$ which is the size of the alphabet (i.e. the range of characters that make up your plaintext and ciphertext). And say $m = x \times n$ is the largest value you have that is not higher than $y$ where $y$ is the largest size produced by your random number generator. For each character: Take values from the random number generator ...



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