hisoka Posted June 13, 2018 Share Posted June 13, 2018 This is about RC4 encryption . It is well known that in RC4 encryption , the keystream is xored with the plaintext to give the ciphertext . It is well known too that , in order to generate the keystream , which is needed in the process of encryption as i mentioned , a user defined password is used . That is to say a password is needed to generate the keystream . So my question is this : If we , ONLY , know the ciphertext and know that the PASSWORD used to generate the keystream - and therefore that ciphertext - is an ENGLISH WORD composed of 6 characters . Is it possible , based only on these two piece of information , to get this English word or this password . If yes . HOW? Link to comment Share on other sites More sharing options...
justsomeguy Posted June 13, 2018 Share Posted June 13, 2018 It sounds like you want to brute force it. That means trying all combinations. So you just need to loop through all possible 6-character words (I'm assuming case matters, so that's 52 letters, assuming no accented or non-Latin characters), and try each one with all possible inputs up to the length you want to check, to see if that passphrase plus that input results in the output you're looking for. If you start this now then one of your descendants will probably get the answer. I'm only partly serious. There are several descriptions of attacks against RC4 that you may be able to use depending on how the original keystream was generated. Link to comment Share on other sites More sharing options...
hisoka Posted June 13, 2018 Author Share Posted June 13, 2018 Quote There are several descriptions of attacks against RC4 that you may be able to use depending on how the original keystream was generated. there are of course but I could not find methods , concerning RC4 , that can help me recover the password used in RC4 encryption supposing that the password is an English word of 6 letters . Could you describe some because I could not find concrete ones . Quote It sounds like you want to brute force it do you know a software or a tool that can be used to brute force this 6 letters password ? I looked for hours in the internet but I could not find a tool . Link to comment Share on other sites More sharing options...
justsomeguy Posted June 13, 2018 Share Posted June 13, 2018 I have not done any research into breaking RC4, I'm sorry. Link to comment Share on other sites More sharing options...
hisoka Posted June 13, 2018 Author Share Posted June 13, 2018 ok thank you Link to comment Share on other sites More sharing options...
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