SIST ETS 300 175-7 E3:2005

SLOVENSKI STANDARD
01-julij-2005
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Digital Enhanced Cordless Telecommunications (DECT); Common Interface (CI); Part 7:
Security features
Ta slovenski standard je istoveten z: ETS 300 175-7 Edition 3
ICS:
33.070.30 'LJLWDOQHL]EROMãDQH Digital Enhanced Cordless
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2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.

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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ETS 300 175-7: September 1997
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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ETS 300 175-7: September 1997
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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ETS 300 175-7: September 1997
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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ETS 300 175-7: September 1997
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ETS 300 175-7: September 1997
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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ETS 300 175-7: September 1997
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 proprietary algorithms. The use of proprietary algorithms may, however, limit roaming in the
public access service environment, as well as the use of PPs in different environments.
For example, for performance reasons, the key stream generator will need to be implemented in hardware
in PPs and FPs. The use of proprietary generators will then limit the interoperability of systems provided
by different manufacturers.
Two standard algorithms have been specified. These are the DECT Standard Authentication Algorithm
(DSAA, see annex H) and the DECT Standard Cipher (DSC), (see annex I).
Because of the confidential nature of the information contained in them, these annexes are not included in
this ETS. However, the algorithms will be made available to DECT equipment manufacturers. The DSAA
may also need to be made available to public access service operators who, in turn, may need to make it
available to manufacturers of authentication modules.
Clause 6 is concerned with integrating the security features into the DECT system. Four aspects of
integration are considered. The first aspect is the association of user security parameters (in particular,
authentication keys) with DECT identities. This is the subject of subclause 6.2. The second aspect of
integration is the definition of the NWK layer protocol elements and message types needed for the
exchange of authentication parameters across the air interface. This is dealt with in subclause 6.3. The
MAC layer procedures for the encryption of data passed over the air interface are the subject of
subclause 6.4. Finally, subclause 6.5 is concerned with security attributes which DECT systems may
support, and the NWK layer messages needed to enable PPs and FPs to identify which security
algorithms and keys will be used to provide the various security services.
Clause 7 is concerned with key management issues. Careful management of keys is fundamental to the
effective operation of a security system, and subclause 7.2 is intended to provide guidance on this subject.
Subclause 7.2 includes an explanation of how the DECT security features may be supported by different
key management options.
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ETS 300 175-7: September 1997
For example, schemes which allow authentication keys to be held in a central location within a public
access service network are described, as are schemes which allow authentication keys to be derived
locally in public access service base stations. Subclause 7.2 is very much less specific than the other
subclauses in this ETS. This is because the key management issues discussed are not an integral part of
the CI. In the end it is up to network operators and service providers to decide how they are going to
manage their cryptographic keys. This ETS can at best provide some suggestions and guidelines.
The main text is supplemented by a set of informative annexes. There are two types of annex. Those of
the first type provide background information justifying the inclusion of a particular service, or the use of a
particular type of mechanism in the security features. Those of the second type provide guidance on the
use and management of certain of the security features. The content of each of the annexes is briefly
reviewed below.
Annex A contains the results of a security threats analysis which was undertaken prior to designing the
DECT security features.
Annex B is concerned with the impact of the security features on roaming, in particular with the concurrent
use of a PP in public access service, wireless Private Branch eXchange (PBX) and residential
environments.
Annex C is provided for background information. It contains a justification for some of the decisions taken
by EG-1, e.g. why symmetric rather than public key (asymmetric) cryptographic mechanisms were
selected.
Annex D provides an overview of the DECT security features specified in this ETS.
No security system is perfect, and annex E discusses the limitations of the DECT security features.
Annex F relates the security features specified in this ETS to the DECT environments identified in
ETR 015. Each of the local networks identified in the reference model is considered in turn. For each of
these networks a security profile is suggested. The networks considered are Public Switched Telephone
Network (PSTN), Integrated Services Digital Network (ISDN), X.25, Global System for Mobile
communications (GSM), Local Area Networks (LANs) and public access service.
Annex G consists of a brief discussion of the compatibility of DECT and GSM authentication. In particular,
the concept of a DECT Authentication Module (DAM) is considered and its functionality compared with the
functionality of the GSM Subscriber Interface Module (SIM).
Annex H refers to the DECT standard authentication algorithm.
Annex J refers to the DECT standard cipher.
Annex K provides a bibliography of informative references.
Annex L provides clarifications, bit mappings and examples for DSAA and DSC.

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ETS 300 175-7: September 1997
AC Authentication Code
IV Initialisation Value obtained from fram e counter
CK Cipher Key
SCK Static Cipher Key
Authentication
KS Session Authentication Key
UAK [128]
Key Selection
KS'
Reverse Authentication Key
B2
UPI [e.g. 128] RAND F
Value generated and transm itted by FP
RAND P Value generated and transm itted by PP
RES 1 Value com puted and transm itted by PP
RES 2 Value com puted and transm itted by FP
RS Value transm itted by FP in authentication protocol
UAK [128]
B1
UAK User authentication Key
UPI User Personal Identity
DCK Derived Cipher Key
K Authentication Key
A11, A12 Authentication Processes
AC [e.g. 16-32]
B1
A21, A22 Authentication Processes
B1, B2 Authentication Key Stream Processes
KSG
Key Stream Generator
K [128]
Authentication of
PP processes
RES1 [32]
A11
KS [128]
RS [64]
A12
RAND F [64] DCK
CK [64]
Key
SCK
SCK [64]
KSG
Stream
IV [35]
Key Stream generation
Authentication of
for encryption process
FP processes
A21
KS' [128]
A22
RES2 [32]
RAND P [64]
Figure 1: Overview of DECT security processes

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ETS 300 175-7: September 1997
1 Scope
This European Telecommunication Standard (ETS) is part of the Digital Enhanced Cordless
Telecommunications (DECT) Common Interface (CI) and specifies the security architecture, the types of
cryptographic algorithms required, the way in which they are to be used, and the requirements for
integrating the security features provided by the architecture into the DECT CI. It also describes how the
features can be managed and how they relate to certain DECT fixed systems and local network
configurations.
The security architecture is defined in terms of the security services which are to be supported at the CI,
the mechanisms which are to be used to provide the services, and the cryptographic parameters, keys
and processes which are associated with these mechanisms.
The security processes specified in this ETS are each based on one of two cryptographic algorithms:
- an authentication algorithm; and
- a key stream generator.
The architecture is, however, algorithm independent, and either the DECT standard algorithms, or
appropriate proprietary algorithms, or indeed a combination of both can, in principle, be employed. The
use of the employed algorithm is specified in this ETS.
Integration of the security features is specified in terms of the protocol elements and processes required
at the Network (NWK) and Medium Access Control (MAC) layers of the CI.
The relationship between the security features and various network elements is described in terms of
where the security processes and management functions may be provided.
This ETS does not address implementation issues. For instance, no attempt is made to specify whether
the DSAA should be implemented in the PP at manufacture, or whether the DSAA or a proprietary
authentication algorithm should be implemented in a detachable module. Similarly, this ETS does not
specify whether the DSC should be implemented in hardware in all PPs at manufacture, or whether
special PPs should be manufactured with the DSC or proprietary ciphers built into them. The security
architecture supports all these options, although the use of proprietary algorithms may limit roaming and
the concurrent use of PPs in different environments.
2 Normative references
This ETS incorporates, by dated or undated reference, provisions from other publications. These
normative references are cited at the appropriate places in the text and the publications are listed
hereafter. For dated references, subsequent amendments to or revisions of any of these publications
apply to this ETS only when incorporated in it by amendment or revision. For undated references the latest
edition of the publication referred to applies.
[1] ETS 300 175-1: "Digital Enhanced Cordless Telecommunications (DECT);
Common Interface (CI); Part 1: Overview".
[2] ETS 300 175-3: "Digital Enhanced Cordless Telecommunications (DECT);
Common Interface (CI); Part 3: Medium Access Control (MAC) layer".
[3] ETS 300 175-5: "Digital Enhanced Cordless Telecommunications (DECT);
Common Interface (CI); Part 5: Network (NWK) layer".
[4] ETS 300 175-6: "Digital Enhanced Cordless Telecommunications (DECT);
Common Interface (CI); Part 6: Identities and addressing".

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ETS 300 175-7: September 1997
3 Definitions and abbreviations
3.1 Definitions
For the purposes of this ETS, the following definitions apply:
algorithm: A mathematical process or function that transforms an input into an output. In cryptographic
applications an algorithm is a process used for encipherment, decipherment or non-reversible
encipherment under control of a key.
algorithm identifier: A designator to show which algorithm is in use, so that the correct one may be
chosen.
asymmetric algorithm: See public key algorithm.
authentication: The corroboration that an entity is the one that is claimed.
Cipher Key (CK): A value that is used to determine the transformation of plaintext to ciphertext in a
cryptographic algorithm.
Cipher Key (CK) generation: A process for generating cryptographic keys.
ciphertext: The output of a cryptographic algorithm. Ciphertext is not intelligible unless (in a reversible
algorithm) the reverse transformation is performed.
confidentiality: Rendering information secret as ciphertext unless the capability is possessed to recover
the plaintext from ciphertext.
countermeasure: A device, instrument or procedure used to counteract or defend against a threat.
cryptography: Literally secret writing. Used to describe the hiding of information.
Data Encryption Standard (DES): United States Federal data encryption standard.
decipherment: The rendering of ciphertext into plaintext.
DECT Standard Authentication Algorithm (DSAA): An algorithm used for authentication in DECT.
DECT Standard Cipher (DSC): An algorithm used for data encryption in DECT.
encipherment: The rendering of plaintext into ciphertext.
FEAL algorithm: Fast Encryption Algorithm; a particular encryption algorithm in the public domain.
GSM: A pan-European standard for digital mobile telephones in the 900 - 1 000 MHz band.
impersonation: Where one identity claims the part of another identity.
Integrated Services Digital Network (ISDN): A digital telecommunications infrastructure to the
Consultative Committee on International Telegraphy and Telephony (CCITT) standards.
key management: The way in which cryptographic keys are generated, distributed and used.
Key Stream Generator (KSG): A cryptographic algorithm which produces a stream of binary digits which
can be used for encipherment and decipherment.
Local Area Network (LAN): Electronic systems which are interconnected and in physical proximity to
each other.
masquerading: Where one identity plays the part of, or acts as, another identity.

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ETS 300 175-7: September 1997
mutual authentication: Where two entities corroborate the identity of each other.
Personal Identity Number (PIN): A short sequence of numbers (usually 4 - 8 digits) which may be used
in an authentication process to prove identity. The term User Personal Identity (UPI) may also be used.
plaintext: Information or data which is intelligible to everyone.
proprietary algorithm: An algorithm which is the intellectual property of a legal entity.
public access service: A service that provides access to a public network for the general public.
public key algorithm: A cryptographic algorithm in which a different key is used for encipherment and for
decipherment. Also known as an asymmetric algorithm.
random number: A number generated by a non-deterministic process.
RS: A value used to establish authentication session keys, as defined in subclause 4.4.3.
RSA (Rivest, Shamir & Adleman) algorithm: A public key algorithm.
security attribute: A protocol element indicating security services, mechanisms, processes or algorithms
that are supported.
Session Key (KS): A key which is used only for a single session; a session may be a single connection or
call, or it may be a number of calls made by a particular user through a particular system (e.g. the calls
made by a roaming portable with a particular visited network).
Subscriber Interface Module (SIM): A smart card used for authentication in GSM.
stream cipher: An algorithm in which the output is combined bit by bit with plaintext to produce the
ciphertext.
symmetric algorithm: A cryptographic algorithm in which the same key is used for both encipherment
and decipherment.
synchronization: Methods used to ensure that time correspondence exists between processes to ensure
that data is not repeated or lost.
threat: An indication of coming evil.
User Authentication Key (UAK): A cryptographic key held by a user to prove identity. May also be
combined with a PIN ("Something you have and something you know").
XRES1: An expected response calculated by an Fixed radio Termination (FT), as defined in
subclause 4.4.2.
XRES2: An expected response calculated by a Portable radio Termination (PT), as defined in
subclause 4.4.2.
X.25: A packet switched network based on CCITT Recommendation X.25.

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ETS 300 175-7: September 1997
3.2 Abbreviations
For the purposes of this ETS, the following abbreviations apply:
A Algorithm
AC Authentication Code
BCT Business Cordless Telephone
CI Common Interface
CK Cipher Key
C-plane Control plane
CRFP Cordless Radio Fixed Part
DAM DECT Authentication Module
DCK Derived Cipher Key
DECT Digital Enhanced Cordless Telecommunications
DES Data Encryption Stan
...