Which encryption algorithm does WPA use?

Explanation:

The RC4 Encryption Algorithm, developed by Ronald Rivest of RSA, is a shared key stream
cipher algorithm requiring a secure exchange of a shared key. The symmetric key algorithm is
used identically for encryption and decryption such that the data stream is simply XORed with the
generated key sequence. The algorithm is serial as it requires successive exchanges of state
entries based on the key sequence. Hence implementations can be very computationally
intensive. The RC4 encryption algorithm is used by standards such as IEEE 802.11 within WEP
(Wireless Encryption Protocol) using 40 and 128-bit keys. Published procedures exist for cracking
the security measures as implemented in WEP.