Data Encryption - Symbol Spectrum24 AP-3020 Reference Manual

A TIM is a compressed virtual bitmap identifying the AP associated MUs in
PSP mode that have buffered directed messages. MUs issue a poll request
when APs issue a TIM. A beacon with the broadcast-indicator bit set causes
the MU to note DTIM Count field value. The value informs the MU of the
beacons remaining before next DTIM. This ensures the MU turns on the
receiver for the DTIM and the following BC/MC packet transmissions.

1.3.10 Data Encryption

Mobile nodes and other hosts on any network face possible information
theft. This occurs when an unauthorized user eavesdrops on someone else to
glean information. The absence of a physical connection makes wireless
links particularly vulnerable to this form of theft. Encryption becomes the
most efficient method in preventing information theft and improving data
security. Encryption requires scrambling and coding of information, typically
with mathematical formulas called algorithms, before the information is
transmitted over a communications link or network. An algorithm is a set of
instructions or formula for scrambling the data. A key is the specific code
used by the algorithm to encrypt or decrypt the data. Decryption is the
decoding and unscrambling of the received encrypted data. The same
device, host computer or front-end processor, usually performs both
encryption and decryption. The data transmit or receive direction determines
whether the encryption or decryption function is performed. This device takes
the plain text and scrambles or encrypts it and transmits the data over the
network, typically by mathematically combining the key with the plain text as
prescribed by the algorithm. At the receiving end another device takes the
encrypted text and decrypts, unscrambles, the text resulting in the original
plain text. An authorized user can know the algorithm, but cannot interpret
the encrypted data without the appropriate key. Only the sender and receiver
of the transmitted data know the secret key. Symbol uses the Wired
Equivalent Privacy (WEP) algorithm, specified in IEEE 802.11 section 8, for
encryption and decryption. WEP uses the same secret key for both encrypting
and decrypting plain text. Typically an external key management service
distributes the secret key. Users should change the key often for added
security. IEEE 802.11 defines two types of authentication, Open System and
Shared Key. Open system authentication is a null authentication algorithm.
Shared key authentication is an algorithm where both the AP and the MU
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Introduction
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