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After reading about RC4, it seems that it's nothing else than:

  1. the plaintext stream is just XOR'ed with a pseudo-random sequence that

  2. is initialized/seeded with the key

Is there something else in the algorithm?

Is there a general name for stream ciphers that use a XOR with a (pseudo-random) sequence seeded by key?

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Is there something else in the algorithm?

No, that's it: just a pseudorandom generator (which in RC4's case turned out not to be that random) whose output is XORed with the message.

Is there a general name for stream ciphers that use a XOR with a (pseudo-random) sequence seeded by key?

Yes — it's stream cipher.

(While you could certainly apply a stream cipher using different invertible binary operations (e.g., addition or subtraction modulo 256), that provides absolutely no benefit over XOR, so nobody ever does it. In both theory and practice, everybody will think of XOR when you say "stream cipher".)

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