1. doc.: IEEE 802.15-03/174r0 Submission March, 2003 Rene Struik, Certicom Corp.Slide 1 Project: IEEE P802.15 Working Group for Wireless Personal Area Networks (WPANs) Submission Title: [Rationale for Public Key Security in 802.15.3] Date Submitted: [12 March, 2003] Source: [Rene Struik] Company [Certicom Corp.] Address [5520 Explorer Drive, 4th Floor, Mississauga, ON Canada L4W 5L1] Voice:[+1 (905) 501-6083], FAX: [+1 (905) 507-4230], E-Mail:[rstruik@certicom.com] Re: [03/054r1] Abstract:[This document discusses the impact of and lacking rationale for the removal of public key security from the 802.15.3 draft during Sponsor Ballot comment resolution (of Draft D15) at the IEEE 802 Interim Meeting in Ft. Lauderdale (January 13-17, 2003).] Purpose:[Highlight major changes in 802.15.3 WPAN security, inconsistencies in approach within the IEEE 802.15.3 WPAN task group and between different IEEE 802 groups. Raise awareness in 802.15.3 and 802.15.3a community of limited remaining security provisions in Draft D16.] Notice:This document has been prepared to assist the IEEE P802.15. It is offered as a basis for discussion and is not binding on the contributing individual(s) or organization(s). The material in this document is subject to change in form and content after further study. The contributor(s) reserve(s) the right to add, amend or withdraw material contained herein. Release:The contributor acknowledges and accepts that this contribution becomes the property of IEEE and may be made publicly available by P802.15.

2. doc.: IEEE 802.15-03/174r0 Submission March, 2003 Rene Struik, Certicom Corp.Slide 2 Rationale for Public Key Security in IEEE 802.15.3(a) WPANs René Struik, Certicom Research

3. doc.: IEEE 802.15-03/174r0 Submission March, 2003 Rene Struik, Certicom Corp.Slide 3 Outline 1.WPAN Network Security 2.Security Changes to the 802.15.3 Specification – Impact on 802.15.3(a) – Rationale (?) — ANNEX A

4. doc.: IEEE 802.15-03/174r0 Submission March, 2003 Rene Struik, Certicom Corp.Slide 4 Access control to the piconet itself Restriction of access to scarce network resources to authorized devices only, to ensure objectives including the following: - proper bandwidth allocation; - protection of commands (e.g., those regulating network membership); - power drain savings. Control of access to message traffic between piconet devices Restriction of access to information secured between members of a group of WPAN devices to precisely these group members. This includes any of the following objectives: - Confidentiality. Prevent external parties from learning the content of exchanged messages. - Data integrity/message authentication. Prevent external parties from modifying or injecting messages in undetected way. WPAN Network Security (1)

5. doc.: IEEE 802.15-03/174r0 Submission March, 2003 Rene Struik, Certicom Corp.Slide 5 Access control to the piconet itself Restriction of access to scarce network resources to authorized devices only, to ensure objectives including the following: - proper bandwidth allocation; - protection of commands (e.g., those regulating network membership); - power drain savings. WPAN Network Security (2) PNC A A piconet enlarged piconet Authorization: Authentication + Membership test (ACL) (side-effect: shared link key A – PNC) Public key techniques, since ad-hoc, spontaneous network

6. doc.: IEEE 802.15-03/174r0 Submission March, 2003 Rene Struik, Certicom Corp.Slide 6 Control of access to message traffic between Network devices Restriction of access to information secured between members of a group of WPAN devices to precisely these group members. This includes any of the following objectives: - Confidentiality. Prevent external parties from learning the content of exchanged messages. - Data integrity/message authentication. Prevent external parties from modifying or injecting messages in undetected way. WPAN Network Security (3) PNC A B Peer-to-peer security: Data: Encryption + Integrity Commands: Integrity PNC DB Broadcast security: Data: Encryption + Integrity Beacons: Integrity A C Key transport: distribution of keys to devices

7. doc.: IEEE 802.15-03/174r0 Submission March, 2003 Rene Struik, Certicom Corp.Slide 7 Access control to the piconet itself Restriction of access to scarce network resources to authorized devices only, to ensure objectives including the following: - proper bandwidth allocation; - protection of commands (e.g., those regulating network membership); - power drain savings. WPAN Network Security (4) PNC A A piconet enlarged piconet Authorization: Authentication + Membership test (ACL) (side-effect: shared link key A – PNC) Draft D15  D16: ‘Public key Exorcism (03/054r1)’ Declared Out of scope Public key techniques, since ad-hoc, spontaneous network

8. doc.: IEEE 802.15-03/174r0 Submission March, 2003 Rene Struik, Certicom Corp.Slide 8 Control of access to message traffic between Network devices Restriction of access to information secured between members of a group of WPAN devices to precisely these group members. This includes any of the following objectives: - Confidentiality. Prevent external parties from learning the content of exchanged messages. - Data integrity/message authentication. Prevent external parties from modifying or injecting messages in undetected way. WPAN Network Security (5) PNC A B Peer-to-peer security: Data: Encryption + Integrity Commands: Integrity PNC DB Broadcast security: Data: Encryption + Integrity Beacons: Integrity A C Key transport: distribution of keys to devices Draft D15  D16: No changes

9. doc.: IEEE 802.15-03/174r0 Submission March, 2003 Rene Struik, Certicom Corp.Slide 9 Security Changes to 802.15.3 Specification (1) Impact of Security Changes Draft D15  D16 NO mechanism left for device authentication in 802.15.3 specification REMAINS: mechanism for key updates and secure data transport Inconsistent: key transport left in, key agreement left out (conceptually the same) Consequences: IEEE 802.15.3(a) WPANs: no secure piconet access mechanism specified (since 802.15.3 MAC re-used for 802.15.3a) Lack of interoperability between devices Uncertainty about secure operation of networks Severe impact on: - time-to-market (someone else has to define authentication now) - market size (no interoperability, so no ‘network effects’) - industry acceptance In short: Change sacrifices secure piconet operation (what is rationale?)

10. doc.: IEEE 802.15-03/174r0 Submission March, 2003 Rene Struik, Certicom Corp.Slide 10 Security Changes to 802.15.3 Specification (2) Rationale Security Changes Draft D15  D16 (according to 03/054r1) ‘Paul Nikolich felt authentication to be out of scope’ Comments: Opinion expressed as 802 member, not as Chair IEEE 802 Opinion poorly interpreted by 802.15.3 Chair: - ‘security suites out of scope’  authentication for higher layers - ‘to be discussed at March Plenary’  premature removal authentication (put process in place to solve issue) - options: remains within WG, LinkSec, or 802.1  1 option: removal Opinion inconsistent with practices elsewhere in IEEE 802 standards (see Annex A) Improper use of Sponsor Ballot comments (CID #19, Dan Bailey): - (speculation) Comment based on ‘yet another break of NTRUEncrypt’ Insufficient discussion about alternative means for solving authentication problem: - 802.1x mechanism: in ‘adhoc’ network to be integrated with each device!! - LinkSec ECSG will solve this: just formed, composed of people alien to WPAN requirements, no desire to solve WPAN problems (mainly Ethernet) - Industry consortium will solve this: timeline?? Uncertainty about secure operation of networks Severe impact on: - time-to-market (someone else has to define authentication now) - market size (no interoperability, so no ‘network effects’) - industry acceptance In short: Change sacrifices secure piconet operation (what is rationale?)

11. doc.: IEEE 802.15-03/174r0 Submission March, 2003 Rene Struik, Certicom Corp.Slide 11 ANNEX A 1.Security Architectural Framework 2.Partitioning within various IEEE 802 Standards – IEEE 802.11 WLAN – IEEE 802.15.4 WPAN – IEEE 802.15.3 WPAN (Draft D15) – IEEE 802.15.3 WPAN (Draft D16)

12. doc.: IEEE 802.15-03/174r0 Submission March, 2003 Rene Struik, Certicom Corp.Slide 12 Security Architectural Framework

13. doc.: IEEE 802.15-03/174r0 Submission March, 2003 Rene Struik, Certicom Corp.Slide 13 Overview Key Establishment Key Transport Data Transport Outline

14. doc.: IEEE 802.15-03/174r0 Submission March, 2003 Rene Struik, Certicom Corp.Slide 14 Security Architectural Framework: Overview (1) Security mechanisms: 1.Public-key or symmetric-key key establishment mechanism. Derivation of link key between two devices, based on authentic public keys or symmetric keys of both parties, including evidence on whom this link key is shared with. 2.Symmetric-key key transport mechanism. Secure transfer of data key from one device to other(s), based on link key(s) between sender and recipient(s). 3.Symmetric-key data transfer mechanism(s). Secure and/or authentic data transfer between devices that share the data key (confidentiality/data integrity/authenticity). Security policy: … Note: Security mechanisms 1 and 2 may be combined (distinction based on implementation cost considerations only).

15. doc.: IEEE 802.15-03/174r0 Submission March, 2003 Rene Struik, Certicom Corp.Slide 15 Security Architectural Framework: Overview (2) key distribution AB Data key repository Data key maintenance Data key repository Data key maintenance Wrapped data key info Wrapped data key info ACL Maintenance ACL Maintenance ACL initialization ACL initialization B AAuthentication, key establishment Wrapped public key info Extracted public key info Wrapped public key info Extracted public key info Public key verification CA key initialization Certificate maintenance Public key verification CA key initialization Certificate maintenance (Link key, A, B) data transfer AB Wrapped data Encryptor/ decryptor Encryptor/ decryptor data Data key Key info Key info Data key Other Key Management Key Usage

16. doc.: IEEE 802.15-03/174r0 Submission March, 2003 Rene Struik, Certicom Corp.Slide 16 Security Architectural Framework: Authorization (1) Authorization and key establishment is based on each of the following: (1)Evidence regarding the true identity of the other device; (2)Evidence whether one wants to communicate with this explicitly identified device. Cryptographic mechanisms: 1.Public-key key establishment mechanism. Derivation of link key between two devices, based on authentic public keys of both parties, including evidence on whom this link key is shared with. 2.Symmetric-key key establishment mechanism. Derivation of link key between two devices, based on secret and authentic pre-shared key between both parties, including evidence on whom this link key is shared with. Non-cryptographic mechanisms: 1.Acceptability test. Establishment whether a particular device is to be accepted, based on a membership test of a so-called Access Control List (ACL).

17. doc.: IEEE 802.15-03/174r0 Submission March, 2003 Rene Struik, Certicom Corp.Slide 17 Security Architectural Framework: Authorization (2a) (public-key scenario) ACL Maintenance ACL Maintenance ACL initialization ACL initialization B AAuthentication, key establishment Wrapped public key info Extracted public key info Wrapped public key info Extracted public key info Public key verification CA key initialization Certificate maintenance Public key verification CA key initialization Certificate maintenance (Link key, A, B) Notes: - The authentication protocol establishes a symmetric link key between the devices (since it is an authenticated key establishment protocol). - Authenticated key establishment is based on a specific public-key protocol (e.g., ECC-based), using manual, explicit (e.g., X509), or implicit certificates. - Certificate maintenance and ACL maintenance are not discussed any further here.

18. doc.: IEEE 802.15-03/174r0 Submission March, 2003 Rene Struik, Certicom Corp.Slide 18 Security Architectural Framework: Authorization (2b) (symmetric-key scenario) ACL Maintenance ACL Maintenance ACL initialization ACL initialization B AAuthentication, key establishment Symmetric key info Extracted symmetric key Symmetric key info Extracted symmetric key Symm. key verification Symm. key initialization Symmetric-key maintenance Symm. key verification Symm. key initialization Symmetric-key maintenance (Link key, A, B) Notes: - The authentication protocol establishes a symmetric link key between the devices (since it is an authenticated key establishment protocol). - Authenticated key establishment is based on a specific symmetric-key protocol, using pre-shared secret keys. - Symmetric-key maintenance and ACL maintenance are not discussed any further here.

19. doc.: IEEE 802.15-03/174r0 Submission March, 2003 Rene Struik, Certicom Corp.Slide 19 Security Architectural Framework: Key transport (1) Key transport is based on each of the following: (1)Availability of a shared link key with the recipient; (2)Evidence whether one wants to communicate with this explicitly identified device. Cryptographic mechanisms: 1.Symmetric-key key transport mechanism. Secure transfer of data key from one device to other(s), based on link key(s) between sender and recipient(s).

20. doc.: IEEE 802.15-03/174r0 Submission March, 2003 Rene Struik, Certicom Corp.Slide 20 Security Architectural Framework: Key transport (2) Data key repository key distribution AB Data key maintenance Data key repository Data key maintenance Wrapped data key info Wrapped data key info (Link key, A, B) Notes: - Authenticated key transport may be based on the data protection mode that yields both confidentiality and authenticity. - Key transport must include authentic info on, e.g., the key originator, the distribution group (key-sharing parties), and the version of the key. (The string Key Id:=(Key originator || KeySeqNo) seems to be a good choice.) - Key storage and key update mechanisms are not discussed any further here.

21. doc.: IEEE 802.15-03/174r0 Submission March, 2003 Rene Struik, Certicom Corp.Slide 21 Security Architectural Framework: Data transport (1) Data transport is based on each of the following: (1)Availability of a shared data key with the recipient(s); (2)Evidence whether one wants to communicate with this explicitly identified device. Cryptographic mechanisms: 1.Data transfer mechanism(s). Secure and/or authentic data transfer between devices that share the data key (confidentiality/data integrity/authenticity).

22. doc.: IEEE 802.15-03/174r0 Submission March, 2003 Rene Struik, Certicom Corp.Slide 22 Security Architectural Framework: Data transport (2) Notes: - Data transport may be based on any negotiated data protection mode that yields a combination of confidentiality and authenticity (for predefined taxonomy) - Data transport must include authentic info on, e.g., the used data key(s), the sender, and a message sequence number (to prevent replay attacks). Data key repository Data key repository data transfer AB Wrapped data Encryptor/ decryptor Encryptor/ decryptor data Data key Key info Key info Data key

23. doc.: IEEE 802.15-03/174r0 Submission March, 2003 Rene Struik, Certicom Corp.Slide 23 Security Architectural Framework – Partitioning within various IEEE 802 standards

24. doc.: IEEE 802.15-03/174r0 Submission March, 2003 Rene Struik, Certicom Corp.Slide 24 IEEE 802.11 WLAN IEEE 802.15.4 WPAN IEEE 802.15.3 WPAN Outline

25. doc.: IEEE 802.15-03/174r0 Submission March, 2003 Rene Struik, Certicom Corp.Slide 25 Security Architectural Framework: 802.11 WLAN (1) key distribution AB Data key repository Data key maintenance Data key repository Data key maintenance Wrapped data key info Wrapped data key info ACL Maintenance ACL Maintenance ACL initialization ACL initialization B AAuthentication, key establishment Symmetric key info Extracted Symmetric key Symmetric key info Extracted Symmetric key Symm. key verification Symmetric key initialization Symmetric-key maintenance Symm. key verification Symmetric key initialization Symmetric-key maintenance (Link key, A, B) data transfer AB Wrapped data Encryptor/ decryptor Encryptor/ decryptor data Data key Key info Key info Data key Other Key Management Key Usage IEEE 802.11 External

26. doc.: IEEE 802.15-03/174r0 Submission March, 2003 Rene Struik, Certicom Corp.Slide 26 Security Architectural Framework: 802.11 WLAN (2) key distribution AB Data key repository Data key maintenance Data key repository Data key maintenance Wrapped data key info Wrapped data key info ACL Maintenance ACL Maintenance ACL initialization ACL initialization B AAuthentication, key establishment Wrapped public key info Extracted public key info Wrapped public key info Extracted public key info Public key verification CA key initialization Certificate maintenance Public key verification CA key initialization Certificate maintenance (Link key, A, B) data transfer AB Wrapped data Encryptor/ decryptor Encryptor/ decryptor data Data key Key info Key info Data key Other Key Management Key Usage IEEE 802.11 External: IEEE 802.1x

27. doc.: IEEE 802.15-03/174r0 Submission March, 2003 Rene Struik, Certicom Corp.Slide 27 Security Architectural Framework: 802.15.4 WPAN key distribution AB Data key repository Data key maintenance Data key repository Data key maintenance Wrapped data key info Wrapped data key info ACL Maintenance ACL Maintenance ACL initialization ACL initialization B AAuthentication, key establishment Wrapped public key info Extracted public key info Wrapped public key info Extracted public key info Public key verification CA key initialization Certificate maintenance Public key verification CA key initialization Certificate maintenance (Link key, A, B) data transfer AB Wrapped data Encryptor/ decryptor Encryptor/ decryptor data Data key Key info Key info Data key Other Key Management Key Usage IEEE 802.15.4 External (e.g., ZigBee)

28. doc.: IEEE 802.15-03/174r0 Submission March, 2003 Rene Struik, Certicom Corp.Slide 28 Security Architectural Framework: 802.15.3 WPAN (1) key distribution AB Data key repository Data key maintenance Data key repository Data key maintenance Wrapped data key info Wrapped data key info ACL Maintenance ACL Maintenance ACL initialization ACL initialization B AAuthentication, key establishment Wrapped public key info Extracted public key info Wrapped public key info Extracted public key info Public key verification CA key initialization Certificate maintenance Public key verification CA key initialization Certificate maintenance (Link key, A, B) data transfer AB Wrapped data Encryptor/ decryptor Encryptor/ decryptor data Data key Key info Key info Data key Other Key Management Key Usage Pre-‘Exorcism’ Situation IEEE 802.15.3 External

29. doc.: IEEE 802.15-03/174r0 Submission March, 2003 Rene Struik, Certicom Corp.Slide 29 Security Architectural Framework: 802.15.3 WPAN (2) key distribution AB Data key repository Data key maintenance Data key repository Data key maintenance Wrapped data key info Wrapped data key info ACL Maintenance ACL Maintenance ACL initialization ACL initialization B AAuthentication, key establishment Wrapped public key info Extracted public key info Wrapped public key info Extracted public key info Public key verification CA key initialization Certificate maintenance Public key verification CA key initialization Certificate maintenance (Link key, A, B) data transfer AB Wrapped data Encryptor/ decryptor Encryptor/ decryptor data Data key Key info Key info Data key Other Key Management Key Usage Post-‘Exorcism’ Situation IEEE 802.15.3 Unknown!