A method and apparatus are described for performing cipher communication in a wireless local area network system. A pseudo noise (PN) code sequence for a plaintext Medium Access Control (MAC) protocol data unit (MPDU) is obtained. An additional authentication data (AAD) is constructed by using at least one field in a header of the plaintext MPDU. A Nonce is constructed from the PN code sequence, an Address 2 field in the header of the plaintext MPDU and a Priority field in the header of the plaintext MPDU. A counter mode (CTR) is generated with cipher block chaining (CBC)-MAC Protocol (CCMP) header. Encrypted data and Message Integrity Code (MIC) are generated by using a temporal key, the AAD, and the Nonce. An encrypted MPDU is generated to be transmitted to a peer station by combining the plaintext MPDU header, the CCMP header, the encrypted data and the MIC.