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P1451.5 Security. Survey and Recommendations By: Ryon Coleman ( rcoleman@3eti.com ) October 16, 2003. Agenda – Analyze Security Techniques Of Candidate Stacks & Present Conclusions. 802.11 / 802.11i Key Management Encryption Authentication Bluetooth Profile Approach Layered Framework
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P1451.5 Security Survey and Recommendations By: Ryon Coleman (rcoleman@3eti.com) October 16, 2003
Agenda – Analyze Security Techniques Of Candidate Stacks & Present Conclusions • 802.11 / 802.11i • Key Management • Encryption • Authentication • Bluetooth • Profile Approach • Layered Framework • ZigBee / 802.15.4 • Government Considerations • Areas for Convergence • Backup Slides
802.11 Security802.11i Specification for Enhanced Security • IEEE 802.1X-based authentication mechanisms are used, with AES in CCMP mode, to establish an 802.11 Robust Security Network (RSN). • IEEE 802.1X-2001 defines a framework based on the Extensible Authentication Protocol (EAP) over LANs, also known as EAPoL. • EAPoL is used to exchange EAP messages. EAP messages perform authentication and are used for key derivation between a STA and an EAP entity known as the Authentication Server (AS). • 802.11i defines a 4-way handshake using EAPoL for key management / key derivation.
802.11 EAP Encapsulation • EAPoL frames are normal IEEE 802.11 data frames, thus they follow the format of IEEE 802.11 MSDUs and MPDUs.
EAPoL for Key Exchange • Packet Type = 0x03 in the 802.1X header indicates EAPoL-Key message. • Used by the Authenticator and Supplicant to derive or exchange cryptographic keying information. • After the association first forms, only IEEE 802.1X protocol messages (i.e., EAP and its associated authentication method) flow across the link until authentication completes • The Supplicant’s IEEE 802.1X Port Access Entity (PAE) filters all non-EAP traffic during this period. Until authentication completes with the distribution of a Pairwise Master Key (PMK), the PAE ensures that only EAP packets are sent or received between this STA and the wireless medium.
AES Counter + CBC-MAC(CCMP) Provides Encryption & Authentication • The CCMP protocol is based on AES using the CCM mode of operation. • The CCM mode combines Counter (CTR) mode privacy and Cipher Block Chaining Message Authentication Code (CBC-MAC) authentication. • These modes have been used and studied for a long time, have well-understood cryptographic properties, and no known patent encumbrances. • They provide good security and performance in both hardware or software.
Bluetooth Security: LAN Access Profile - A Cross-Layered Approach From “Bluetooth Security Whitepaper” Bluetooth SIG Security Expert Group
Bluetooth Security Overview • Bluetooth takes a cross-layered approach to implementing security: • SAFER+ algorithm used at the Baseband for encryption & authentication. • Link Manager specification covers link level procedures for configuring security. • HCI specification details how a host controls security & how security-related events are reported by a Bluetooth module to its host. • Bluetooth SIG whitepaper exists for implementing security and provides examples of how services might use security. • Drawback: SAFER+ (Secure And Fast Encryption Routine) was beaten out by Rijndael for selection for AES in the U.S. • Existing Bluetooth security does not satisfy U.S. DoD requirements.
ZigBee / 802.15.4 Security • Like 802.11i, ZigBee relies on AES CCM as a mainstay for encryption + authentication. • CCM mode consists of CTR mode encryption combined with CBC-MAC authentication to produce an authenticate-and-encrypt block cipher using NIST-approved AES. • AES CCM is intended to provide encryption, sender authentication, and message integrity.
ZigBee Key Management • Currently ZigBee is establishing its key management / key distribution techniques. • Elliptic Curve based techniques are supposedly in the works • Need additional input on ZigBee security from a member representative…
Government Considerations • Currently, there exist four FIPS-approved symmetric key algorithms for encryption: • Advanced Encryption Standard (AES) • Data Encryption Standard (DES) • Triple-DES • Skipjack • AES is the FIPS-Approved symmetric encryption algorithm of choice. • FIPS 197, Advanced Encryption Standard (AES), specifies the AES algorithm (http://csrc.nist.gov/cryptval/) • 802.11i is compliant with NIST FIPS 197 and FIPS 140-2 validation requirements.
Areas for Convergence • AES CCM should be called out by 1451.5 at the MAC sublayer for authentication and encryption. • Key Management is a crucial area for wireless security. 802.11i is good but may be too “heavy” for smart sensors. • Access to ZigBee techniques would be useful in this area • Bluetooth implements a layered approach, but is not in compliance with NIST or DoD requirements. • A strong, layered approach for 1451.5 security would be AES CCM at the MAC plus 802.11i constructs including 802.1X EAPoL for mutual key derivation / key exchange. • Any additional information from Axonn or ZigBee? Form Subgroup?
