41ae97e0dd79f8d0692374ccffe47099.ppt
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Overview of E 2 E Security MAF and MEF CRs Group Name: SEC WG Source: Qualcomm Inc. , Phil Hawkes, Wolfgang Granzow Meeting Date: SEC#23, 2016 -05 -16 Agenda Item: End-to-End Security and Group Authentication
Background • Qualcomm has four open CRs related to End-to-End Security – – SEC-2016 -0065 R 04 -CR_TS-0003_R 2_Updates_to_MAF_Text SEC-2016 -0071 R 02 -CR_TS-0003_Certificate_Enrolment SEC-2016 -0091 -CR_TS-0003_R 2_Certificate_Enrolment_procedure_call_flow SEC-2016 -0092 -CR_TS-0003_Usage-constrained_key_derivation_from_Ke • These changes solve a large set of problems – Difficult to provide separate CRs for each problem, since there are interdependencies • 91 and 92 are text separated from 71 R 01. • For other solutions that could not be presented in separate CRs, the text is highlighted to simplify discussion on whether to include the text or not. – All related to credential provisioning/distribution, mostly • E 2 E Security related, and • Better support for certificates (cert enrolment, cert authn w/ MAF) • This presentation gives an overview of those changes – Summary Slide followed by deeper dive into the individual problems and solutions. – Presentation does not fully describe solutions – see CRs to understand solutions 2
Problem Summary Table Certificate Enrolment [SEC-20150549 R 02] Integration into RSPFs Contribution (SEC 2016 -00…) 71 R 02 Certificate enrolment-specific steps 91 SAEF, ESPrim and ESData should use same technologies with MEF Limiting scope of usage of a symmetric keys established using MEF SAEF, ESPrim or ESData use single extended versions of MEF procedures Security Usage Identifiers (SUIDs) defined for security features – used to limit scope 71 R 02 Key derivation algorithm (stage 3 detail) SAEF, ESPrim or ESData use single extended versions of MAF procedures Security Usage Identifiers (SUIDs) defined for security features – used to limit scope Added MAF Km. Id Retrieval procedure 92 65 R 04 Extend MAF handshake (DTLS/TLS) to allow 65 R 04, 71 R 02 light SAEF, ESPrim and ESData should use same technologies with MAF Limiting scope of usage of a symmetric keys established using MAF No way for MAF to select Km. Id for remotely provisioning symmetric key MAF auth’n could use client + server certs If Enrolee B is enrolled with MEF, fast reauthenticate to retrieve symmetric key Triggering remote mgmt in remote provisioning Solution Summary 71 R 02 65 R 04 blue highlighting Allow use of a symmetric Enrolment Re-Authentication 71 R 02 dark blue Key (Ker) generated during RSPF or provisioned certificate. highlighting RSPF can configure URI for remote mgmt 71 R 02 grey highlighting 3
Key distribution/provisioning for E 2 E (1) • MAF, MAF-SAEF, MEF & RSPFs were specified for key distribution/provisioning when we only had SAEFs for securing communication – Now we also have ESPrim and ESData • IDCC added clause 8. 6 “Remote Security Frameworks for End-to -End Security” defining TEF providing key distribution/provisioning for ESPrim & ESData – As mentioned earlier, more like MAF & operational-phase key distribution • There would be advantages to having same key distribution/provisioning technologies for all of SAEF, ESPrim, ESData – In particular, the overall system becomes less complex 4
Key distribution/provisioning for E 2 E (2) • [0071] MEF/RSPF Impact : – Add text saying provisioned credentials may be also used for ESPrim and ESData – Added support for Usage-Constrained Symmetric Keys, where usage may be MAF, SAEF, ESPrim, ESData … • [0065]MAF Impact : – Extracted MAF-specific details from clause 8. 2. 2. 3 on MAF-Based SAEF and put them in new clause 8. x not specific to SAEFs – Added exchanges (within DTLS/TLS) • Between Source End-Point and MAF (MAF Key Registration) • Between Target End-Point and MAF (MAF Key Retrieval) – Added support for source-generated keys (as in clause 8. 6. 3) • Addition to existing support for “Bootstrapped” keys exported from TLS – Added support for limiting scope of keys to SAEF, ESPrim, ESData, … 5
Limiting Scope of Symmetric Keys • Best practice: limit scope within which symmetric key is used – The safest mechanism is incorporating, into the key derivation, some identifier or label defining the scope • Impact – Security Usage Identifiers (SUIDs) limits scope to • A specific security feature (SAEF, ESPrim, ESData, others? ) • Specific option of security feature, where applicable – e. g. ESData can use a symmetric key for Encryption Only or Signature Only – [0071] RSPF Impact • Symmetric Keys derivation incorporates SUID – [0092] Stage 3 details of key derivation for RSPFs – [0065] MAF Impact • Source End-Point provides MAF with SUID limiting scope of distributed credential • Target End-Point provides SUID to MAF when requesting credential • Currently, derivation of Bootstrapped Kc does not include SUID, but it could easily be changed to include SUID – Generation of source-generated Kc is out of scope. 6
Certificate Enrolment • Purpose – Provisioning Enrolee certificate on behalf of M 2 M SP or M 2 M Trust Enabler – MEF would be appropriate function to facilitate this. Could be part of RSPF – Suggested SEC-2015 -0549 R 02. Change implemented [0071] and [0091] • RSPF Impact [0071] – Previously, RSPF consisted of a TLS handshake providing mutual authentication of Enrolee and MEF – Added “Enrolment exchange” between Enrolee and MEF • Includes instruction from MEF to Enrolee triggering Certificate Enrolment via an identified URI • Updates Overview (8. 3. 1. 2), details in clause 8. 3. 2. 1 (referenced in 8. 3. 2. 2) • Certificate Enrolment procedure call flow (Stage 2 only) [0091] – Stage 3: Propose using Enrolment over Secure Transport (EST) [RFC 7030], relying on mutual authentication in RSPF’s existing TLS handshake – Issue: EST is currently defined only for HTTP/TLS. Release 2 will only support certificate enrolment over HTTP/TLS. • This will be addressed in stage 3 details 7
MAF Km. Id Retrieval procedure • Purpose – Used when remotely provisioning a symmetric key for MAF. Triggers the MAF to • retrieve Km from MAF, • assign Km. Id • provide Km. Id to Enrolee • Impact – MAF Changes [0065] • Referenced in SAEF text (8. 2. 1 overview, 8. 2. 2. 3 MAF SAEF) • Description in MAF Security Framework details (clause 8. x) – RSPF Changes [0071] • Referenced in RSPF text (8. 3. 1. 2, 8. 3. 2. 1) 8
Enrolment Re-authentication • Purpose – Enrolee B may need to retrieve, from MEF, a usage-limited symmetric key provisioned to Enrolee. – Makes sense to allow Enrolee B to use a credential established with MEF when Enrolee B enrolled • Enrolled Certificate or • Symmetric Enrolment Re-Authentication Key (Ker) • RSPF Impact [0071] – 8. 3. 1. 2 and 8. 3. 2. 1 • Generation of symmetric Enrolment Re-Authentication Key (Ker) and Enrolment Re-Authentication Key Identifier (Ker. Id) • Allowing Enrolee B to use enrolled certificate or Ker+Ker. Id for mutual authentication with MAF – Relevant Highlighted using dark blue background 9
Cert Authentication w/ MAF • Purpose – MAF Handshake (TLS/DTLS) currently only supports symmetric keys – Certificate-based TLS might be preferable in some deployments • Advantage: no need for MAF to store secrets for every end-point • Impact – MAF Changes [0065] Details specific to using certificates • 8. x. 2 MAF Credential Configuration • 8. x. 4 MAF Handshake. – RSPF Changes [0071] • 8. 3. 1. 1 (Intro) – Mentions that certs can be used for auth’n w/ MAF • 8. 3. 1. 2 (Overview flow), 8. 3. 2. 1 (Details in PPSK RSPF) – If MEF instructs Enrolee to use a MAF, then MEF indicates to Enrolee whether to use symmetric key or certificate for authentication with MAF – Relevant Highlighted using light blue background 10
Triggering Remote Management • Purpose – Enables the MEF to instruct/configure the Enrolee to perform remote management after the remote security provisioning is completed • RSPF Impact [0071] – As part of Enrolment Exchange, MEF may provide the base URI of a remote management server with which the Enrolee shall initiate contact for remote management – Relevant Highlighted using grey background 11