IVs in WEP encryption First, I'm pretty new to the world of encryption. As I understand it, in WEP, the plaintext and CRC are XOR'd with the IV and the key (or more accurately, the key/stream, which is produced by a pseudo-random generator) to get the resulting ciphertext.

Basically, given two different messages encrypted with the same IV and key, an attacker can XOR both ciphertexts and soon reveal the plaintext.

So, why is the IV sent in plaintext with the message? When the attacker knows the IV, isn't it easier to work out the key and decrypt the messages?
Generally, the security contract for a cipher involving an IV or nonce does not require the IV/nonce to be secret, for the cipher to provide any security.  Not only is there no need to keep the IV/nonce secret, but it often provides negligible additional security to do so, and it often enhances security to use a (public, observable) message sequence number as a nonce.

However, it's anyone's guess what ‘design’ might have gone into WEP, and certainly it had no input from any competent cryptographer, who might have alerted them to the stupidity of their design and to the fact that RC4 was $55v$1@mhadg.production.compuserve.com&gt;, 1994-09-15.">broken within 48 hours of its publication, not to mention the plethora of other ways it has been found to broken since then because people kept using it in protocol after protocol despite being broken.

You could change one small part of WEP's cryptography at a time, and the rest would be just as much of a disaster; the only thing to be done with it is to throw the whole thing out and start over.