Product manual

System description, DECT air interface

Technical Product Manual - DCT1800-GAP

TD 92093 (1/LZBNB 103 108 R4D) / 2006-03-09/ Ver.C

Fig. 43 Authentication of user

6.11.5 Authentication of fixed part

Authentication of the fixed part is invoked/activated by the portable part, typically when it receives the

ZAP command from the fixed part.

The authentication protocol is graphically represented in figures 44 and 45 and follows the following

steps:

1. The portable part sends the message ‘Authentication request’. It contains the authentication

algorithm type and authentication key type to be used and the random number RAND-P.

2. The fixed part calculates K based on UAK and B1 process (see paragraph 6.9). The response

RES2 is based on K, RS and RAND-P.

3. The fixed part sends RS and RES2 to portable part.

4. The portable part calculates K based on UAK and B1 process. The portable part calculates

response XRES2 based on K, RAND-P, RS.

5. The portable part compares RES2 and XRES2. If UAK in fixed part and portable part are the

same (due to subscription process), the results RES2 and XRES2 are the same. In this case the

portable part accepts the authenticity of the fixed part.

Portable

part

Fixed part

Authentication request

- Authentication algorithm type (DSAA)

- Authentication type key (UAK, UPI)

- Random number (RAND-F)

- Number (RS)

Authentication reply

- Response (RES1)

User authenticated

User inputs UPI. UPI, UAK, B2 => K. PP

calculates RES1 based on K, RAND-F,

UAK (subscription data)

UAK,

UPI, B2=> K. FP calculates

XRES1 based on K, RAND-F and RS

FP compares RES1 with XRES1. If

RES1 = XRES1 then user PP

authenticated

UAK, UPI (subscription

data)

- Expected response (XRES1)

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