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EAP Method Update. PSK Design Team Status Update Mar 20, 2006. Design Goals. Create a Pre-Shared Key mechanism, that is based on strong shared secrets meets RFC 3748 and RFC 4017 req’s is simple and compact enough implementable in resource constrained environments. Milestone:
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EAP Method Update PSK Design Team Status Update Mar 20, 2006
Design Goals • Create a Pre-Shared Key mechanism, that • is based on strong shared secrets • meets RFC 3748 and RFC 4017 req’s • is simple and compact enough • implementable in resource constrained environments. • Milestone: • Submit draft by next IETF for WG consideration
Design Team • Jari Arkko • Mohamad Badra • Uri Blumenthal • Charles Clancy • Lakshminath Dondeti • David McGrew • Joseph Salowey • Suman Sharma • Hannes Tschofenig • Jesse Walker
Decisions made so far… (1) • Not based on TLS-PSK • To limit number of required crypto primitives • To simplify implementation • Symmetric key credentials only (no PK) • Performance • Avoiding implications of multi-layered trust/CA • Limiting the number of crypto primitives • No true multi-party (more than 2) • EAP framework shuns three+ party models
Decisions made so far… (2) • Fast resumption: no need • must be fast enough to begin with • Channel binding – must support • Because of tunneling possibilities • Format and encryption req’s are open issues • Algorithm agility – necessary • Because some algorithms are broken, and others will be • How granular “agility” is – is an open issue • Provisioning – SNMP • Simply Not My Problem • Out of scope of this design team
Keying approach • Generation/transport vs. Derivation • Team favors derivation • Both existing proposals do derivation • Charles and Hannes • Looking at transport, but… • not as sound cryptographically
Algorithms to implement • Minimize number of required primitives • Ideally base on one primitive • Implementation simplicity! • Favoring block cipher as base primitive • Example: entire suite based on AES only • FIPS compliance • Team made NIST aware of EMU work • Hope: get NIST to bless EMU key derivation • Compliance with existing FIPS is considered
Open Issues • Randomness source • Can we live with only one peer contributing? • Alternative: both peers must contribute • Cipher selection • Nice to do everything with just one primitive • However need to clear AES with NIST • NIST hasn’t yet defined AES-based key derivation • Algorithm agility – how granular should it be? • Identity Hiding – postpone discussion • Need to see justification/demand first • Likely to be added as an extension (later) • Channel bindings • Define format • Determine if encryption is necessary
Questions? None – Thank you!