ETSI ETS 300 175-7 ed.3 (1997-09)

SLOVENSKI STANDARD
SIST ETS 300 175-7 E3:2005
01-julij-2005
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Digital Enhanced Cordless Telecommunications (DECT); Common Interface (CI); Part 7:
Security features
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ICS:
33.070.30 'LJLWDOQHL]EROMãDQH Digital Enhanced Cordless
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SIST ETS 300 175-7 E3:2005 en
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.

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SIST ETS 300 175-7 E3:2005

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SIST ETS 300 175-7 E3:2005
EUROPEAN ETS 300 175-7
TELECOMMUNICATION September 1997
STANDARD Third Edition
Source: DECT Reference: RE/DECT-030122-7
ICS: 33.020
Key words: DECT, radio, security
Digital Enhanced Cordless Telecommunications (DECT);
Common Interface (CI);
Part 7: Security features
ETSI
European Telecommunications Standards Institute
ETSI Secretariat
Postal address: F-06921 Sophia Antipolis CEDEX - FRANCE
Office address: 650 Route des Lucioles - Sophia Antipolis - Valbonne - FRANCE
X.400: c=fr, a=atlas, p=etsi, s=secretariat - Internet: secretariat@etsi.fr
Tel.: +33 4 92 94 42 00 - Fax: +33 4 93 65 47 16
Copyright Notification: No part may be reproduced except as authorized by written permission. The copyright and the
foregoing restriction extend to reproduction in all media.
© European Telecommunications Standards Institute 1997. All rights reserved.

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ETS 300 175-7: September 1997
Whilst every care has been taken in the preparation and publication of this document, errors in content,
typographical or otherwise, may occur. If you have comments concerning its accuracy, please write to
"ETSI Editing and Committee Support Dept." at the address shown on the title page.

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ETS 300 175-7: September 1997
Contents
Foreword .9
Amendments in this edition .9
Introduction.10
1 Scope .13
2 Normative references.13
3 Definitions and abbreviations .14
3.1 Definitions .14
3.2 Abbreviations .16
4 Security architecture.17
4.1 Background.17
4.2 Security services.17
4.2.1 Authentication of a PT.17
4.2.2 Authentication of an FT .17
4.2.3 Mutual authentication .17
4.2.4 Data confidentiality .17
4.2.5 User authentication .17
4.3 Security mechanisms.18
4.3.1 Authentication of a PT.18
4.3.2 Authentication of an FT .19
4.3.3 Mutual authentication .20
4.3.4 Data confidentiality .20
4.3.4.1 Derived Cipher Key (DCK).21
4.3.4.2 Static Cipher Key (SCK) .21
4.3.5 User authentication .21
4.4 Cryptographic parameters and keys.22
4.4.1 Overview.22
4.4.2 Cryptographic parameters.22
4.4.3 Cryptographic keys.24
4.4.3.1 Authentication key K .24
4.4.3.2 Authentication session keys KS and KS' .25
4.4.3.3 Cipher Key (CK).26
4.5 Security processes.26
4.5.1 Overview.26
4.5.2 Derivation of authentication key, K.26
4.5.2.1 K is derived from UAK .26
4.5.2.2 K is derived from AC.27
4.5.2.3 K is derived from UAK and UPI .27
4.5.3 Authentication processes .27
4.5.3.1 Processes for the derivation of KS and KS'.27
4.5.3.2 Processes for the derivation of DCK, RES1 and RES2.28
4.5.4 Key stream generation .28
4.6 Combinations of security services .29
5 Algorithms for security processes .29
5.1 Background.29
5.1.1 A algorithm .30
5.2 Derivation of session authentication key(s) .30
5.2.1 A11 process .30
5.2.2 A21 process .30
5.3 Authentication and cipher key generation processes .31
5.3.1 A12 process .31

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5.3.2 A22 process. 31
6 Integration of security . 32
6.1 Background . 32
6.2 Association of keys and identities . 32
6.2.1 Authentication key. 32
6.2.1.1 K is derived from UAK. 32
6.2.1.2 K derived from AC. 32
6.2.1.3 K derived from UAK and UPI . 33
6.2.2 Cipher keys. 33
6.3 NWK layer procedures. 33
6.3.1 Background. 33
6.3.2 Authentication exchanges. 34
6.3.3 Authentication procedures. 35
6.3.3.1 Authentication of a PT. 35
6.3.3.2 Authentication of an FT. 36
6.3.4 Transfer of Cipher Key, CK. 36
6.4 MAC layer procedures. 36
6.4.1 Background. 36
6.4.2 MAC layer field structure . 36
6.4.3 Data to be encrypted. 37
6.4.4 Encryption process . 38
6.4.5 Initialization and synchronization of the encryption process . 40
6.4.6 Encryption mode control . 41
6.4.6.1 Background. 41
6.4.6.2 MAC layer messages. 41
6.4.6.3 Procedures for switching to encrypt mode. 41
6.4.6.4 Procedures for switching to clear mode. 44
6.4.7 Handover of the encryption process. 45
6.4.7.1 Bearer handover, uninterrupted ciphering. 45
6.4.7.2 Connection handover, uninterrupted ciphering . 46
6.4.7.3 External handover - handover with ciphering. 46
6.4.8 Modifications for half slot specifications . 46
6.4.8.1 Background. 46
6.4.8.2 MAC layer field structure. 47
6.4.8.3 Data to be encrypted. 47
6.4.8.4 Encryption process. 47
6.4.8.5 Initialization and synchronization of the encryption
process . 48
6.4.8.6 Encryption mode control . 48
6.4.8.7 Handover of the encryption process . 48
6.4.9 Modifications for double slot specifications . 48
6.4.9.1 Background. 48
6.4.9.2 MAC layer field structure. 48
6.4.9.3 Data to be encrypted. 48
6.4.9.4 Encryption process. 49
6.4.9.5 Initialization and synchronization of the encryption
process . 50
6.4.9.6 Encryption mode control . 50
6.4.9.7 Handover of the encryption process . 50
6.4.10 Modifications for multi-bearer specifications. 50
6.5 Security attributes. 50
6.5.1 Background. 50
6.5.2 Authentication protocols . 52
6.5.2.1 Authentication of a PT. 52
6.5.2.2 Authentication of an FT. 53
6.5.3 Confidentiality protocols. 54
6.5.4 Access-rights protocols . 56
6.5.5 Key numbering and storage. 57
6.5.5.1 Authentication keys. 57
6.5.5.2 Cipher keys . 58
6.5.6 Key allocation. 59
6.5.6.1 Introduction . 59

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6.5.6.2 UAK allocation .59
7 Use of security features.60
7.1 Background.60
7.2 Key management options .61
7.2.1 Overview of security parameters relevant for key management.61
7.2.2 Generation of authentication keys.62
7.2.3 Initial distribution and installation of keys .62
7.2.4 Use of keys within the fixed network .63
7.3 Confidentiality service with a Cordless Radio Fixed Part (CRFP) .67
7.3.1 General.67
7.3.2 CRFP initialization of PT cipher key .67
Annex A (informative): Security threats analysis.68
A.1 Introduction.68
A.2 Threat A: impersonating a subscriber identity.69
A.3 Threat B: illegal use of a handset (PP).69
A.4 Threat C: illegal use of a base station (FP).70
A.5 Threat D: impersonation of a base station (FP) .70
A.6 Threat E: illegally obtaining user data and user related signalling information .70
A.7 Conclusions and comments.71
Annex B (informative): Security features and operating environments.73
B.1 Introduction.73
B.2 Definitions.73
B.3 Enrolment options .74
Annex C (informative): Reasons for not adopting public key techniques.75
Annex D (informative): Overview of security features .76
D.1 Introduction.76
D.2 Authentication of a PT.76
D.3 Authentication of an FT .77
D.4 Mutual authentication of a PT and an FT .77
D.4.1 Direct method .77
D.4.2 Indirect method 1 .77
D.4.3 Indirect method 2 .77
D.5 Data confidentiality .77
D.5.1 Cipher key derivation as part of authentication.77
D.5.2 Static cipher key.78
D.6 User authentication .78
D.7 Key management in case of roaming.78
D.7.1 Introduction .78
D.7.2 Use of actual authentication key K.79
D.7.3 Use of session keys.80

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D.7.4 Use of precalculated sets.81
Annex E (informative): Limitations of DECT security . 82
E.1 Introduction. 82
E.2 Protocol reflection attacks . 82
E.3 Static cipher key and short Initial Vector (IV). 82
E.4 General considerations regarding key management. 83
E.5 Use of a predictable challenge in FT authentication. 83
Annex F (informative): Security features related to target networks . 84
F.1 Introduction. 84
F.1.1 Notation and DECT reference model. 84
F.1.2 Significance of security features and intended usage within DECT. 84
F.1.3 Mechanism/algorithm and process requirements . 85
F.2 PSTN reference configurations . 86
F.2.1 Domestic telephone . 86
F.2.2 PBX . 88
F.2.3 Local loop. 90
F.3 ISDN reference configurations . 91
F.3.1 Terminal equipment . 91
F.3.2 Network termination 2 . 92
F.3.3 Local loop. 92
F.4 X.25 reference configuration . 93
F.4.1 Data Terminal Equipment (DTE). 93
F.4.2 PAD equipment . 93
F.5 GSM reference configuration. 93
F.5.1 Base station substation . 93
F.5.2 Mobile Station. 93
F.6 IEEE 802 reference configuration. 93
F.6.1 Bridge. 93
F.6.2 Gateway . 93
F.7 Public access service reference configurations. 94
F.7.1 Fixed public access service reference configuration . 94

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Annex G (informative): Compatibility of DECT and GSM authentication.95
G.1 Introduction.95
G.2 SIM and DAM functionality .95
G.3 Using an SIM for DECT authentication .96
G.4 Using a DAM for GSM authentication .97
Annex H (informative): DECT standard authentication algorithm .98
Annex J (informative): DECT standard cipher.99
Annex K (informative): Bibliography.100
Annex L (normative): Clarifications, bit mappings and examples for DSAA and DSC .101
History.105

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Foreword
This third edition European Telecommunication Standard (ETS) has been produced by the Digital
Enhanced Cordless Telecommunications (DECT) Technical Committee of the European
Telecommunications Standards Institute (ETSI).
Annexes A to K to this ETS are informative. Annex L is normative.
The following cryptographic algorithms are subject to controlled distribution:
a) DECT standard cryptographic algorithms;
b) DECT standard cipher.
These algorithms are distributed on an individual basis. Further information and details of the current
distribution procedures can be obtained from the ETSI Secretariat at the address on the first page of this
ETS.
Further details of the DECT system may be found in the ETSI Technical Reports ETR 015, ETR 043 and
ETR 056.
This ETS forms part 7 of a series of 9 laying down the arrangements for the Digital Enhanced Cordless
Telecommunications (DECT) Common Interface (CI).
Part 1: "Overview".
Part 2: "Physical layer (PHL)".
Part 3: "Medium Access Control (MAC) layer".
Part 4: "Data Link Control (DLC) layer".
Part 5: "Network (NWK) layer".
Part 6: "Identities and addressing".
Part 7: "Security features".
Part 8: "Speech coding and transmission".
Part 9: "Public Access Profile (PAP)".
Transposition dates
Date of adoption: 22 August 1997
Date of latest announcement of this ETS (doa): 31 December 1997
Date of latest publication of new National Standard
or endorsement of this ETS (dop/e): 30 June 1998
Date of withdrawal of any conflicting National Standard (dow): 30 June 1998
Amendments in this edition
This edition of ETS 300 175-7 includes new annex L (normative) compared to the text of ETS 300 175-7,
edition 2.

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Introduction
This ETS contains a detailed specification of the security features which may be provided by DECT
systems. An overview of the processes required to provide all the features detailed in this ETS is
presented in figure 1.
The ETS consists of four main clauses (clauses 4 - 7), together with a number of informative and
normative annexes (A - L). The purpose of this introduction is to briefly preview the contents of each of the
main clauses and the supporting annexes.
Each of the main clauses starts with a description of its objectives and a summary of its contents.
Clause 4 is concerned with defining a security architecture for DECT. This architecture is defined in terms
of the security services which may be offered (subclause 4.2), the mechanisms which need to be used to
provide these services (subclause 4.3), the security parameters and keys required by the mechanisms
(challenges, keys etc.), and which need to be passed across the air interface or held within DECT
Portable Parts (PPs), Fixed Parts (FPs) or other network entities (e.g. management centres)
(subclause 4.4), the processes which are required to provide the security mechanisms (subclause 4.5),
and the recommended combinations of services (subclause 4.6).
Clause 5 is concerned with specifying how certain cryptographic algorithms are to be used for the security
processes. Two algorithms are required:
- a key stream generator; and
- an authentication algorithm.
The key stream generator is only used for the encryption process, and this process is specified in
subclause 4.4. The authentication algorithm may be used to derive authentication session keys and cipher
keys, and is the basis of the authentication process itself. The way in which the authentication algorithm is
to be used to derive authentication session keys is specified in subclause 5.2. The way in which the
algorithm is to be used to provide the authentication process and derive cipher keys is specified in
subclause 5.3.
Neither the key stream generator nor the authentication algorithm are specified in this ETS. Only their
input and output parameters are defined. In principle, the security features may be provided by using
appropriate p
...