ZyXEL Communications MAX-200M1 Series, Руководство пользователя

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ZyXEL MAX-200M1 Series User’s Guide
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In order to ensure network security, the access point and the RADIUS server use a shared
secret key, which is a password they both know. The key is not sent over the network. In
addition to the shared key, password information exchanged is also encrypted to protect the
network from unauthorized access.
Diameter
Diameter (RFC 3588) is a type of AAA server that provides several improvements over
RADIUS in efficiency, security, and support for roaming.
Security Association
The set of information about user authentication and data encryption between two computers
is known as a security association (SA). In a WiMAX network, the process of security
association has three stages.
• Authorization request and reply
The MS/SS presents its public certificate to the base station. The base station verifies the
certificate and sends an authentication key (AK) to the MS/SS.
• Key request and reply
The MS/SS requests a transport encryption key (TEK) which the base station generates
and encrypts using the authentication key.
• Encrypted traffic
The MS/SS decrypts the TEK (using the authentication key). Both stations can now
securely encrypt and decrypt the data flow.
CCMP
All traffic in a WiMAX network is encrypted using CCMP (Counter Mode with Cipher Block
Chaining Message Authentication Protocol). CCMP is based on the 128-bit Advanced
Encryption Standard (AES) algorithm.
‘Counter mode’ refers to the encryption of each block of plain text with an arbitrary number,
known as the counter. This number changes each time a block of plain text is encrypted.
Counter mode avoids the security weakness of repeated identical blocks of encrypted text that
makes encrypted data vulnerable to pattern-spotting.
‘Cipher Block Chaining Message Authentication’ (also known as CBC-MAC) ensures
message integrity by encrypting each block of plain text in such a way that its encryption is
dependent on the block before it. This series of ‘chained’ blocks creates a message
authentication code (MAC or CMAC) that ensures the encrypted data has not been tampered
with.