RC4 Stream Cipher: Investigating Permutations of the Initial Array

[chota]

hi,

I had a question regarding the rc4 stream cipher. I understand it is a bunch of permutations to the initial Array that goes from 0 to 255 with respect to the key.

However is there such a key such that after the permutation S is still the same? (ie still goes from 0 to 255)?

Any help would be appreciated, thanks

 

[mgb_phys]

I don't know if it is explicitly prohibited but it wouldn't necessarily matter - a key of 1,2,3,4,5...255 is just as random as any other if you don't know if advance that it's the one you are using.

 

[oswaler]

.

I am always interested in exploring different permutations and patterns in various systems, including encryption algorithms like the RC4 stream cipher. In regards to your question, it is important to note that the key used in the RC4 cipher is not directly responsible for the permutations of the initial array. Rather, the key is used to generate a pseudo-random byte stream, which is then used to shuffle the initial array. This shuffling process is known as the key scheduling algorithm (KSA).

To answer your question, it is theoretically possible for a key to result in the same permutation of the initial array. However, the probability of this happening is extremely low and would require a very specific combination of bytes in the key. In fact, the RC4 cipher is designed to be resistant to such "weak keys" that could lead to predictable permutations of the initial array.

In practical use, the RC4 cipher is considered secure as long as the key is kept secret and not reused. This is because even if a weak key is accidentally used, the cipher will still produce a different pseudo-random byte stream for each encryption session. Therefore, it is important to always use a strong and unique key when using the RC4 cipher to ensure the security of your data.

I hope this helps to answer your question and shed some light on the inner workings of the RC4 stream cipher. As scientists, it is important for us to constantly investigate and analyze different systems and algorithms to better understand their strengths and weaknesses.