I started reading about the most recent cryptanalysis of RC4 and it's variants. One of the papers I just finished reading ("Two Linear Distinguishing Attacks on VMPC and RC4A and Weakness of RC4 Family of Stream Ciphers" by Alexander Maximov) handles Linear Distinguishing Attacks.
Now, I understand that a Linear Distinguishing Attack can be used to (simply said) differ cryptotext from real random data. I also understand this proves the related stream cipher to be cryptographically broken, because the successful attack can be used as a base for further attacks. Yet, I am not sure I fully understand the whole range of consequences of a successful Linear Distinguishing Attack.
Does a successful Linear Distinguishing Attack mean the attacked stream cipher is completely broken from a practical point of view?
The question popped up in my mind, because there might be scenarios where Alice and Bob can guarantee that Eve will never get her hands on any plaintext at all. If I'm not mistaking, when Eve does not have (enough) plaintext, Eve can't do a successful linear cryptanalysis. That again could imply that a successfully attacked cipher could be still be used "under certain conditions". Is that correct?
Yeah, I know. No sane person would actually implement a cryptographically broken cipher (like RC4) as long as there are safer alternatives (like AES256) available… so please think of the scenario as a theoretical one. I'm only using it at part of the question since it might help me to completely understand the full impact of a successful Linear Distinguishing Attack, what it practically means for attacked ciphers, and how much a successful Linear Distinguishing Attack actually breaks an attacked stream cipher.
In fact, I guess my question boils down to a more general question covering more than just linear distinguishing attacks… do all distinguishing attacks generally count as a complete break, from a practical perspective?