ETSI TS 133 179 V13.8.0 (2019-04)

LTE; Security of Mission Critical Push To Talk (MCPTT) over LTE (3GPP TS 33.179 version 13.8.0 Release 13)

RTS/TSGS-0333179vd80

General Information

• Status: Published
• Publication Date: 29-Apr-2019
• Technical Committee: 3GPP SA 3 - Security
• Current Stage: 12 - Completion
• Completion Date: 30-Apr-2019

Standards Content (Sample)

TECHNICAL SPECIFICATION
LTE;
Security of Mission Critical Push To Talk (MCPTT) over LTE
(3GPP TS 33.179 version 13.8.0 Release 13)

3GPP TS 33.179 version 13.8.0 Release 13 1 ETSI TS 133 179 V13.8.0 (2019-04)

Reference
RTS/TSGS-0333179vd80
Keywords
LTE,SECURITY
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3GPP TS 33.179 version 13.8.0 Release 13 2 ETSI TS 133 179 V13.8.0 (2019-04)
Intellectual Property Rights
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Foreword
This Technical Specification (TS) has been produced by ETSI 3rd Generation Partnership Project (3GPP).
The present document may refer to technical specifications or reports using their 3GPP identities, UMTS identities or
GSM identities. These should be interpreted as being references to the corresponding ETSI deliverables.
The cross reference between GSM, UMTS, 3GPP and ETSI identities can be found under
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Modal verbs terminology
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provisions).
"must" and "must not" are NOT allowed in ETSI deliverables except when used in direct citation.
ETSI
3GPP TS 33.179 version 13.8.0 Release 13 3 ETSI TS 133 179 V13.8.0 (2019-04)
Contents
Intellectual Property Rights . 2
Foreword . 2
Modal verbs terminology . 2
Foreword . 7
1 Scope . 8
2 References . 8
3 Definitions and abbreviations . 9
3.1 Definitions . 9
3.2 Abbreviations . 10
4 Overview of MCPTT security . 10
4.1 General . 10
4.2 Signalling plane security architecture. 10
4.3 Application plane security architecture . 11
4.3.1 General . 11
4.3.2 User authentication and authorisation . 11
4.3.3 Identity keying of users and services . 12
4.3.4 Protection of application plane signalling . 13
4.3.5 Media security . 13
4.3.5.1 General . 13
4.3.5.2 Media security for group communications. . 13
4.3.5.3 Media security for private calls . 15
5 Authentication and authorization . 16
5.1 General . 16
5.2 LTE access authentication and security mechanism. 17
5.3 Authentication for SIP core access . 17
5.4 Authentication for HTTP-1 . 17
5.5 User authentication . 17
5.5.1 Identity management functional model . 17
5.5.2 User authentication framework . 18
5.5.3 OpenID Connect (OIDC) . 19
5.5.3.1 General . 19
5.5.3.2 User authentication example using Username/Password . 21
5.6 MCPTT user authorization . 21
5.6.1 General . 21
5.6.2 MCPTT user service authorization with MCPTT Server. 23
5.6.2.0 General . 23
5.6.2.1 Using SIP REGISTER . 23
5.6.2.2 Using SIP PUBLISH . 24
6 Signalling plane protection . 25
6.1 SIP-1 interface security . 25
6.2 HTTP-1 interface security . 25
7 End-to-end communication security . 25
7.1 Overview . 25
7.2 Key provisioning and management . 26
7.2.1 General . 26
7.2.2 Functional model for key management . 26
7.2.2.0 General . 26
7.2.2.1 Reference point CSC-8 (between key management server and the key management client within
the MCPTT UE) . 27
7.2.2.2 Reference point CSC-9 (between the key management server and the key management client
within the MCPTT Server) . 27
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7.2.2.3 Reference point CSC-10 (between the key management server and the key management client
within a group management server) . 27
7.2.3 Security procedures for key management . 27
7.2.4 Provisioned key material to support end-to-end communication security . 28
7.3 Group call key distribution . 29
7.3.1 General . 29
7.3.2 Security procedures for GMK provisioning . 31
7.3.3 Key Identification and purpose tags. 32
7.3.4 Group creation procedure . 32
7.3.5 Dynamic group keying . 32
7.3.5.1 General . 32
7.3.5.2 Group regrouping procedures (within a single MCPTT system) . 33
7.3.5.3 Group regrouping procedures (involving multiple MCPTT systems) . 33
7.3.6 Derivation of SRTP/SRTCP master keys . 34
7.3.7 Group member GMK management . 34
7.4 Private call key distribution . 35
7.4.1 General . 35
7.4.2 Security procedures (on-network) . 36
7.4.3 Security procedures (off-network) . 37
7.4.4 Derivation of SRTP/SRTCP master keys . 38
7.4.5 Void . 39
7.5 Protection of media stream (SRTP) . 39
7.5.1 General . 39
7.5.2 Security procedures for media stream protection. 40
7.6 Protection of offline floor and media control signalling (SRTCP) . 41
7.6.1 General . 41
7.6.2 Security procedures for offline floor and media control protection . 42
7.7 Protection of MBMS subchannel control messages (SRTCP) . 43
7.7.1 General . 43
7.7.2 Key distribution . 43
7.7.3 Derivation of SRTCP master keys . 44
8 Inter/Intra domain interface security . 45
8.1 General . 45
9 Protection of floor control and sensitive application signalling . 45
9.1 Key agreement for protection of floor control and sensitive application data (Client to Server) . 45
9.1.1 Identity-based key management for Client Server Key (CSK) . 45
9.1.2 Creation of the CSK . 46
9.1.3 Secure distribution of the CSK . 46
9.1.3.0 General . 46
9.1.3.1 MIKEY-SAKKE I_MESSAGE . 46
9.1.3.2 Distribution of CSK during MCPTT Service Authorization and group subscription . 47
9.1.3.3 Obtaining CSK from the I_MESSAGE. 47
9.1.3.4 Procedure . 47
9.2 Key agreement for protection of floor control and sensitive application data between servers . 48
9.3 Protection of XML content . 49
9.3.1 General . 49
9.3.2 Protected content . 49
9.3.3 Key agreement . 50
9.3.4 Confidentiality protection using XML encryption (xmlenc) . 50
9.3.4.1 General . 50
9.3.4.2 XML content encryption . 50
9.3.4.3 XML URI attribute encryption . 51
9.3.5 Integrity protection using XML signature (xmlsig) . 52
9.4 Key agreement for online floor control (SRTCP) . 53
9.4.1 General . 53
9.4.2 Key agreement between MCPTT client and MCPTT Server . 53
9.4.3 Key agreement between MCPTT Servers . 53
9.4.4 Key agreement for multicast from MCPTT Server . 53
9.4.5 Derivation of SRTCP key material . 53
Annex A (normative): Security requirements . 55
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A.0 Introduction . 55
A.1 Configuration & service access . 55
A.2 Group key management. 55
A.3 On-network operation. 55
A.4 Ambient listening . 56
A.5 Data communication between MCPTT network entities . 56
A.6 Key stream re-use . 56
A.7 Late entry to group communication . 56
A.8 Private call confidentiality . 57
A.9 Off-network operation . 57
A.10 Privacy of MCPTT identities . 57
A.11 User authentication and authorization requirements . 58
Annex B (normative): OpenID connect profile for MCPTT . 59
B.0 General . 59
B.1 MCPTT tokens . 59
B.1.1 ID token . 59
B.1.1.0 General . 59
B.1.1.1 Standard claims . 59
B.1.1.2 MCPTT claims . 59
B.1.2 Access token . 60
B.1.2.0 Introduction. 60
B.1.2.1 Standard claims . 60
B.1.2.2 MCPTT claims . 60
B.2 MCPTT client registration. 60
B.3 Obtaining tokens . 60
B.3.0 General . 60
B.3.1 Native MCPTT client . 61
B.3.1.0 General . 61
B.3.1.1 Authentication Request . 61
B.3.1.2 Authentication response . 62
B.3.1.3 Token request . 63
B.3.1.4 Token Response . 63
B.4 Refreshing an access token . 64
B.4.0 General . 64
B.4.1 Access token request . 64
B.4.2 Access token response . 65
B.5 Using the token to access MCPTT resource servers . 65
B.6 Token validation . 66
B.6.1 ID token validation . 66
B.6.2 Access token validation . 66
B.7 IdMS interface security . 66
Annex C (informative): OpenID connect detailed flow . 67
C.1 Detailed flow for MCPTT user authentication and registration using OpenID Connect . 67
Annex D (Normative): KMS provisioning messages to support MCPTT . 69
D.1 General aspects . 69
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D.2 KMS requests . 69
D.3 KMS responses . 70
D.3.0 General . 70
D.3.1 KMS certificates . 70
D.3.1.1 Description . 70
D.3.1.2 Fields . 71
D.3.1.3 User IDs . 71
D.3.2 User Key Provision . 71
D.3.2.1 Description . 71
D.3.2.2 Fields . 72
D.3.3 Example KMS response XML . 72
D.3.3.1 Example KMSInit XML . 72
D.3.3.2 Example KMSKeyProv XML. 73
D.3.3.3 Example KMSCertCache XML . 75
D.3.4 KMS Response XML schema . 77
D.3.4.1 Base XML schema . 77
D.3.4.2 Security extension to KMS response XML schema . 79
Annex E (normative): MIKEY message formats for media security . 81
E.1 General aspects . 81
E.1.0 Introduction . 81
E.1.1 MIKEY common fields . 81
E.2 MIKEY message structure for GMK distribution . . 81
E.3 MIKEY message structure for PCK distribution . 82
E.4 MIKEY message structure for CSK distribution . 83
E.5 MIKEY general extension payload to support 'SAKKE-to-self' . 83
E.6 MIKEY general extension payload to encapsulate parameters associated with a GMK . 84
E.6.1 General . 84
E.6.2 Void . 84
E.6.3 MCPTT group ID . 84
E.6.4 Activation time . 85
E.6.5 Text . 85
E.6.6 Reserved . 85
E.6.7 Void . 85
E.6.8 Cryptography . 85
E.6.9 Status . 86
E.6.10 Expiry time . 86
E.6.11 Key Type . 86
E.7 Hiding identities within MIKEY messages . 87
Annex F (normative): Key derivation and hash functions . 88
F.1 KDF interface and input parameter construction . 88
F.1.1 General . 88
F.1.2 FC value allocations . 88
F.1.3 Calculation of the User Salt for GUK-ID generation . 88
F.1.4 Calculation of keys for application data protection . 88
F.2 Hash Functions . 89
F.2.1 Generation of MIKEY-SAKKE UID . 89
Annex G (informative): Change history . 90
History . 91

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3GPP TS 33.179 version 13.8.0 Release 13 7 ETSI TS 133 179 V13.8.0 (2019-04)
Foreword
rd
This Technical Specification has been produced by the 3 Generation Partnership Project (3GPP).
The contents of the present document are subject to continuing work within the TSG and may change following formal
TSG approval. Should the TSG modify the contents of the present document, it will be re-released by the TSG with an
identifying change of release date and an increase in version number as follows:
Version x.y.z
where:
x the first digit:
1 presented to TSG for information;
2 presented to TSG for approval;
3 or greater indicates TSG approved document under change control.
y the second digit is incremented for all changes of substance, i.e. technical enhancements, corrections,
updates, etc.
z the third digit is incremented when editorial only changes have been incorporated in the document.
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3GPP TS 33.179 version 13.8.0 Release 13 8 ETSI TS 133 179 V13.8.0 (2019-04)
1 Scope
The present document specifies the security architecture, procedures and information flows needed to protect the
mission critical push to talk (MCPTT) service. The architecture includes mechanisms for authentication, protection of
MCPTT signalling and protection of MCPTT media. Security for both MCPTT group calls and MCPTT private calls
operating in on-network and off-network modes of operation is specified.
The functional architecture for MCPTT is defined in 3GPP TS 23.179 [2], the corresponding service requirements are
defined in 3GPP TS 22.179 [3].
The MCPTT service can be used for public safety applications and also for general commercial applications e.g. utility
companies and railways. As the security model is based on the public safety environment, some security features may
not be applicable to MCPTT for commercial purposes.
2 References
The following documents contain provisions which, through reference in this text, constitute provisions of the present
document.
- References are either specific (identified by date of publication, edition number, version number, etc.) or
non-specific.
- For a specific reference, subsequent revisions do not apply.
- For a non-specific reference, the latest version applies. In the case of a reference to a 3GPP document (including
a GSM document), a non-specific reference implicitly refers to the latest version of that document in the same
Release as the present document.
[1] 3GPP TR 21.905: "Vocabulary for 3GPP Specifications".
[2] 3GPP TS 23.179: "Functional architecture and information flows to support mission critical
communication services; Stage 2".
[3] 3GPP TS 22.179: "Mission Critical Push To Talk (MCPTT) over LTE; Stage 1".
[4] 3GPP TS 33.210: ''3G security; Network Domain Security (NDS); IP network layer security''.
[5] 3GPP TS 33.310: "Network Domain Security (NDS); Authentication Framework (AF)".
[6] 3GPP TS 33.203: "3G security; Access security for IP-based services".
[7] Void.
[8] 3GPP TS 33.328: ''IP Multimedia Subsystem (IMS) media plane security''.
[9] IETF RFC 6507: ''Elliptic Curve-Based Certificateless Signatures for Identity-Based Encryption
(ECCSI)''.
[10] IETF RFC 6508: ''Sakai-Kasahara Key Encryption (SAKKE)''.
[11] IETF RFC 6509: ''MIKEY-SAKKE: Sakai-Kasahara Key Encryption in Multimedia Internet
KEYing (MIKEY)''.
[12] IETF RFC 3550: ''RTP: A Transport Protocol for Real-Time Applications''.
[13] IETF RFC 3711: "The Secure Real-time Transport Protocol (SRTP)".
[14] 3GPP TS 33.401: "3GPP System Architecture Evolution (SAE); Security architecture".
[15] 3GPP TS 23.228: "IP Multimedia Subsystem (IMS); Stage 2".
[16] 3GPP TS 33.222: "Generic Authentication Architecture (GAA); Access to network application
functions using Hypertext Transfer Protocol over Transport Layer Security (HTTPS)".
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3GPP TS 33.179 version 13.8.0 Release 13 9 ETSI TS 133 179 V13.8.0 (2019-04)
[17] 3GPP TS 33.220: "Generic Authentication Architecture (GAA); Generic Bootstrapping
Architecture (GBA)".
[18] NIST FIPS 180-4: "Secure Hash Standard (SHS)".
[19] IETF RFC 6749: "The OAuth 2.0 Authorization Framework".
[20] IETF RFC 6750: "The OAuth 2.0 Authorization Framework: Bearer Token Usage".
[21] OpenID Connect 1.0: "OpenID Connect Core 1.0 incorporating errata set 1",
http://openid.net/specs/openid-connect-core-1_0.html.
[22] IETF RFC 3830: "MIKEY: Multimedia Internet KEYing".
[23] IETF RFC 3602: "The AES-CBC Cipher Algorithm and Its Use with IPsec".
[24] IETF RFC 4771: "Integrity Transform Carrying Roll-Over Counter for the Secure Real-time
Transport Protocol (SRTP)".
[25] IETF RFC 6043: "MIKEY-TICKET: Ticket-Based Modes of Key Distribution in Multimedia
Internet KEYing (MIKEY)".
[26] IETF RFC 7714: ''AES-GCM Authenticated Encryption in the Secure Real-time Transport
Protocol (SRTP)''.
[27] W3C: "XML Encryption Syntax and Processing Version 1.1", https://www.w3.org/TR/xmlenc-
core1/.
[28] W3C: "XML Signature Syntax and Processing (Second Edition)", http://www.w3.org/TR/xmldsig-
core/.
[29] IETF RFC 5905: "Network Time Protocol Version 4: Protocol and Algorithms Specification".
[30] IETF RFC 5480: "Elliptic Curve Cryptography Subject Public Key Information".
[31] IETF RFC 6090: "Fundamental Elliptic Curve Cryptography Algorithms".
[32] IETF RFC 7519: "JSON Web Token (JWT)".
[33] IETF RFC 7662: "OAuth 2.0 Token Introspection".
[34] IETF RFC 3394: "Advanced Encryption Standard (AES) Key Wrap Algorithm".
[35] IETF RFC 7515: "JSON Web Signature (JWS)".
[36] NIST Special Publication 800-38D: "Recommendation for Block Cipher Modes of Operation:
Galois/Counter Mode (GCM) and GMAC".
[37] IETF RFC 2045: "Multipurpose Internet Mail Extensions (MIME) Part One: Format of Internet
Message Bodies".
[38] IETF RFC 2392: "Content-ID and Message-ID Uniform Resource Locators".
[39] 3GPP TS 24.380: " Mission Critical Push To Talk (MCPTT) media plane control; Protocol
specification".
3 Definitions and abbreviations
3.1 Definitions
For the purposes of the present document, the terms and definitions given in 3GPP TR 21.905 [1] and the following
apply. A term defined in the present document takes precedence over the definition of the same term, if any, in 3GPP
TR 21.905 [1].
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Floor: Floor(x) is the largest integer smaller than or equal to x.
3.2 Abbreviations
For the purposes of the present document, the abbreviations given in 3GPP TR 21.905 [1] and the following apply. An
abbreviation defined in the present document takes precedence over the definition of the same abbreviation, if any, in
3GPP TR 21.905 [1].
CSC Common Services Core
GMK Group Master Key
GMK-ID Group Master Key Identifier
GMS Group Management Server
GUK-ID Group User Key Identifier
IdM Identity Management
IdMS Identity Management Server
KMS Key Management Server
MBCP Media Burst Control Protocol
MCPTT Mission Critical Push to Talk
MKI Master Key Identifier
MSCCK MBMS subchannel control key
OIDC OpenID Connect
PCK Private Call Key
PCK-ID Private Call Key Identifier
PSK Pre-Shared Key
SRTCP Secure Real-Time Transport Control Protocol
SRTP Secure Real-Time Transport Protocol
SSRC Synchronization Source
TBCP Talk Burst Control Protocol
TrK KMS Transport Key
UID User Identifier for MIKEY-SAKKE (referred to as the 'Identifier' in RFC 6509 [11])
4 Overview of MCPTT security
4.1 General
The MCPTT security architecture defined in this document is designed to meet the security requirements defined in
Annex A. The MCPTT s
...