I am studying the RC4 stream cipher, particularly when it used to be applied in the TLS/SSL protocol.
Is it safe to say the KSA acts like an extractor taking in the shared secret key, k (between 128bits and 256bits) and then blows it up to a scrambled 256 byte array?
Then this is essentially used as a "seed" for the PRGA that comes next?
If the above is correct, then what is the difference then between an extractor and a key-scheduling algorithm?
NOTE: I have zero intention of using RC4 in any TLS application, this is purely for my own education.