First off, it is not clear we should implement WEP at all since it is fatally flawed. This has been known for about a decade, there have been at least two better algorithms added to the standards, & the only reason anyone would need WEP today would be to connect to an old router in an obviously insecure way. https://www.schneier.com/blog/archives/2007/04/breaking_wep_in.html https://www.tomshardware.com/reviews/wireless-security-hack,2981-4.html Twenty years ago the FreeS/WAN project implemented IPsec for Linux & deliberately did not include things like single DES which were known to be insecure: https://www.freeswan.org/freeswan_trees/freeswan-1.99/doc/compat.html#dropped I think a similar policy was would be a fine idea for the kernel today & WEP is hopelessly insecure. > > As I am attempting to explain, ecb(arc4) does not implement this API correctly > > because it updates the *key* after each operation, not the IV. I doubt this is > > documented anywhere, but this can only be changed if people aren't relying on it > > already. It is more the case that the API does not apply to arc4, or more generally to stream ciphers, than that "ecb(arc4) does not implement this API correctly". ECB (electronic code book) is a mode of operation for block ciphers https://en.wikipedia.org/wiki/Block_cipher_mode_of_operation Stream ciphers do not have those modes. For that matter, not all block cipher modes use an IV. The very common CBC mode -- the only mode used in IPsec, for example -- does, but others including ECB do not. I do not know of any mode that ever updates the IV. CBC uses the IV with the first block & on all other blocks uses the ciphertext from the previous block the same way; one might call that updating the IV I suppose, but I do not see why one would want to. > It sounds to me like it was broken and should be fixed. So our vote / > preference is to have ARC4 fixed to follow the proper semantics. As I see it, those are clearly not "he proper semantics" for a stream cipher & the question of forcing it into them should not even arise. One alternative would be to drop arc4. That would make sense if WEP is the only usage & we elect to drop WEP. One could also argue the arc4 itself is insecure & should go, but I'm not sure that is accurate. Certainly there have been some published attacks & other stream ciphers are now generally preferrred, but I have not followed things closely enough to know if RC$ should be considered fatally flawed. A better choice might be to change the interface, defining a new interface for stream ciphers and/or generalising the interface so it works for either stream ciphers or block ciphers.
