1. Overview of E2E Security CRs
Group Name: SEC WG
Source: Qualcomm Inc., Phil Hawkes, Wolfgang Granzow
Meeting Date: SEC#22.4,
Agenda Item: End-to-End Security and Group Authentication

2. Background Qualcomm has four open CRs related to End-to-End Security
SEC R04-CR_TS-0003_R2_Updates_to_MAF_Text
SEC R02-CR_TS-0003_Certificate_Enrolment
SEC CR_TS-0003_R2_Certificate_Enrolment_procedure_call_flow
SEC 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 71R01.
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
E2E 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

3. Summary Table Problem Solution Summary Contribution (SEC-2016-00…)
Certificate Enrolment [SEC R02]
Integration into RSPFs
71R02
Certificate enrolment-specific steps 91
SAEF, ESPrim and ESData should use same technologies with MEF
SAEF, ESPrim or ESData use single extended versions of MEF procedures
Limiting scope of usage of a symmetric keys established using MEF
Security Usage Identifiers (SUIDs) defined for security features – used to limit scope
Key derivation algorithm (stage 3 detail) 92
SAEF, ESPrim and ESData should use same technologies with MAF
SAEF, ESPrim or ESData use single extended versions of MAF procedures
65R04
Limiting scope of usage of a symmetric keys established using MAF
No way for MAF to select KmId for remotely provisioning symmetric key
Added MAF KmId Retrieval procedure
MAF auth’n could use client + server certs
Extend MAF handshake (DTLS/TLS) to allow
65R04, 71R02 light blue highlighting
If Enrolee B is enrolled with MEF, fast re-authenticate to retrieve symmetric key
Allow use of a symmetric Enrolment Re-Authentication Key (Ker) generated during RSPF or provisioned certificate.
71R02 dark blue highlighting
Triggering remote mgmt in remote provisioning
RSPF can configure URI for remote mgmt
71R02 grey highlighting

4. Key distribution/provisioning for E2E (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

5. Key distribution/provisioning for E2E (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 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,…

6. 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.

7. Certificate Enrolment
Purpose
Provisioning Enrolee certificate on behalf of M2M SP or M2M Trust Enabler
MEF would be appropriate function to facilitate this. Could be part of RSPF
Suggested SEC R02. 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 ( ), details in clause (referenced in )
Certificate Enrolment procedure call flow (Stage 2 only) [0091]
Stage 3: Propose using Enrolment over Secure Transport (EST) [RFC7030], 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

8. MAF KmId Retrieval procedure
Purpose
Used when remotely provisioning a symmetric key for MAF. Triggers the MAF to
retrieve Km from MAF,
assign KmId
provide KmId to Enrolee
Impact
MAF Changes [0065]
Referenced in SAEF text (8.2.1 overview, MAF SAEF)
Description in MAF Security Framework details (clause 8.x)
RSPF Changes [0071]
Referenced in RSPF text ( , )

9. 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]
and
Generation of symmetric Enrolment Re-Authentication Key (Ker) and Enrolment Re-Authentication Key Identifier (KerId)
Allowing Enrolee B to use enrolled certificate or Ker+KerId for mutual authentication with MAF
Relevant Highlighted using dark blue background

10. 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]
(Intro)
Mentions that certs can be used for auth’n w/ MAF
(Overview flow), (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

11. 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