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IEEE Std 802.16-2001

LOCAL AND METROPOLITAN AREA NETWORKS—PART 16:

Code: 5

Attributes are shown in Table 28.

 

Table 28—Auth Reply attributes

 

 

Attribute

Contents

 

 

AUTH-Key

Authorization (AUTH) Key, encrypted with the target client SS’s public key

 

 

Key-Lifetime

Authorization Key’s active lifetime

 

 

Key-Sequence-Number

Authorization key sequence number

 

 

(one or more) SA-

Each compound SA-Descriptor Attribute specifies an SAID and additional properties

Descriptor(s)

of the SA.

 

 

6.2.2.3.9.4 Authorization Reject (Auth Reject) message

The BS responds to an SS’s authorization request with an Authorization Reject message if the BS rejects the SS’s authorization request.

Code: 6

Attributes are shown in Table 29.

 

Table 29—Auth Reject attributes

 

 

Attribute

Contents

 

 

Error-Code

Error code identifying reason for rejection of authorization request.

 

 

Display-String (optional)

Display String providing reason for rejection of authorization request.

 

 

The Error-Code and Display-String attributes describe to the requesting SS the reason for the authorization failure.

6.2.2.3.9.5 Key Request message

Code: 7

Attributes are shown in Table 30.

 

Table 30—Key Request attributes

 

 

Attribute

Contents

 

 

Key-Sequence-Number

Authorization key sequence number

 

 

SAID

Security Association ID

 

 

HMAC-Digest

Keyed secure hash algorithm (SHA) message digest

 

 

58

Copyright © 2002 IEEE. All rights reserved.

AIR INTERFACE FOR FIXED BROADBAND WIRELESS ACCESS SYSTEMS

IEEE Std 802.16-2001

The HMAC Digest attribute shall be the final attribute in the message’s attribute list.

Inclusion of the keyed digest allows the BS to authenticate the Key Request message. The HMAC-Digest’s authentication key is derived from the Authorization Key. See 7.5 for details.

6.2.2.3.9.6 Key Reply message

Code: 8

Attributes are shown in Table 31.

 

Table 31—Key Reply attributes

 

 

Attribute

Contents

 

 

Key-Sequence-Number

Authorization key sequence number

 

 

SAID

Security Association ID

 

 

TEK-Parameters

“Older” generation of key parameters relevant to SAID

 

 

TEK-Parameters

“Newer” generation of key parameters relevant to SAID

 

 

HMAC-Digest

Keyed SHA message digest

 

 

The TEK-Parameters Attribute is a compound attribute containing all of the keying material corresponding to a particular generation of an SAID’s TEK. This would include the TEK, the TEK’s remaining key lifetime, its key sequence number, and the cipher block chaining (CBC) initialization vector. The TEK is encrypted. See 11.2.8 for details.

At all times the BS maintains two sets of active generations of keying material per SAID. (A set of keying material includes a TEK and its corresponding CBC initialization vector.) One set corresponds to the “older” generation of keying material, the second set corresponds to the “newer” generation of keying material. The newer generation has a key sequence number one greater than (modulo 4) that of the older generation. 7.4.1 specifies BS requirements for maintaining and using an SAID’s two active generations of keying material.

The BS distributes to a client SS both generations of active keying material. Thus, the Key Reply message contains two TEK-Parameters Attributes, each containing the keying material for one of the SAID’s two active sets of keying material.

The HMAC Digest attribute shall be the final attribute in the message’s attribute list.

Inclusion of the keyed digest allows the receiving client to authenticate the Key Reply message and ensure SS and BS have synchronized Authorization Keys. The HMAC-Digest’s authentication key is derived from the Authorization Key. See 7.5 for details.

6.2.2.3.9.7 Key Reject message

Receipt of a Key Reject indicates the receiving client SS is no longer authorized for a particular SAID.

Code: 9

Copyright © 2002 IEEE. All rights reserved.

59

IEEE Std 802.16-2001

LOCAL AND METROPOLITAN AREA NETWORKS—PART 16:

Attributes are shown in Table 32.

 

Table 32—Key Reject attributes

 

 

Attribute

Contents

 

 

Key-Sequence-Number

Authorization key sequence number

 

 

SAID

Security Association ID

 

 

Error-Code

Error code identifying reason for rejection of Key Request

 

 

Display-String (optional)

Display string containing reason for Key Reject

 

 

HMAC-Digest

Keyed SHA message digest

 

 

The HMAC-Digest attribute shall be the final attribute in the message’s attribute list.

Inclusion of the keyed digest allows the receiving client to authenticate the Key Reject message and ensure SS and BS have synchronized Authorization Keys. The HMAC-Digest’s authentication key is derived from the Authorization Key. See 7.5 for details.

6.2.2.3.9.8 Authorization Invalid message

The BS may send an Authorization Invalid message to a client SS as:

a)an unsolicited indication, or

b)a response to a message received from that SS.

In either case, the Authorization Invalid message instructs the receiving SS to reauthorize with its BS.

The BS sends an Authorization Invalid in response to a Key Request if (1) the BS does not recognize the SS as being authorized (i.e., no valid Authorization Key associated with the requesting SS) or (2) verification of the Key Request’s keyed message digest (in HMAC-Digest Attribute) failed, indicating a loss of Authorization Key synchronization between SS and BS.

Code: 10

Attributes are shown in Table 33.

 

Table 33—Authorization Invalid attributes

 

 

Attribute

Contents

 

 

Error-Code

Error code identifying reason for Authorization Invalid

 

 

Display-String (optional)

Display String describing failure condition

 

 

60

Copyright © 2002 IEEE. All rights reserved.

AIR INTERFACE FOR FIXED BROADBAND WIRELESS ACCESS SYSTEMS

IEEE Std 802.16-2001

6.2.2.3.9.9 TEK Invalid message

The BS sends a TEK Invalid message to a client SS if the BS determines that the SS encrypted an uplink PDU with an invalid TEK (i.e., an SAID’s TEK key sequence number), contained within the received packet’s MAC Header, is out of the BS’s range of known, valid sequence numbers for that SAID.

Code: 11

Attributes are shown in Table 34.

 

Table 34—TEK Invalid attributes

 

 

Attribute

Contents

 

 

Key-Sequence-Number

Authorization key sequence number

 

 

SAID

Security Association ID

 

 

Error-Code

Error code identifying reason for TEK Invalid message

 

 

Display-String (optional)

Display string containing vendor-defined information

 

 

HMAC-Digest

Keyed SHA message digest

 

 

The HMAC-Digest attribute shall be the final attribute in the message’s attribute list.

Inclusion of the keyed digest allows the receiving client to authenticate the TEK Invalid message and ensure SS and BS have synchronized Authorization Keys. The HMAC-Digest’s authentication key is derived from the Authorization Key. See 7.5 for details.

6.2.2.3.9.10 Authentication Information (Authent Info) message

The Authent Info message contains a single CA-Certificate Attribute, containing an X.509 CA certificate for the manufacturer of the SS. The SS’s X.509 user certificate shall have been issued by the certification authority identified by the X.509 CA certificate.

Authent Info messages are strictly informative; while the SS shall transmit Authent Info messages as indicated by the Authentication state model (7.2.4), the BS may ignore them.

Code: 12

Attributes are shown in Table 35.

 

Table 35—Authent Info attributes

 

 

Attribute

Contents

 

 

CA-Certificate

Certificate of manufacturer CA that issued SS certificate

 

 

The CA-certificate attribute contains an X.509 CA certificate for the CA that issued the SS’s X.509 user certificate. The external certification authority issues these CA certificates to SS manufacturers.

Copyright © 2002 IEEE. All rights reserved.

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