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IEEE 802 Response to 6N15523

IEEE 802 Response to 6N15523. Authors:. Date: 2013-03-18. Abstract. A submission for ISO/IEC JTC1/SC6 in 802 format is presented. IEEE 802 Response to 6N15523– “A Comparative Analysis of TePA /KA4 and IEEE 802.1X Security”. ISO/IEC JTC1 SC6 Seoul, Republic of Korea June, 2013. Agenda.

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IEEE 802 Response to 6N15523

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  1. IEEE 802 Response to 6N15523 Authors: • Date:2013-03-18 IEEE 802 Working Group, IEEE 802

  2. Abstract • A submission for ISO/IEC JTC1/SC6 in 802 format is presented. IEEE 802 Working Group, IEEE 802

  3. IEEE 802 Liason to ISO/IEC JTC1 SC6 IEEE 802 Response to 6N15523– “A Comparative Analysis of TePA/KA4 and IEEE 802.1X Security” ISO/IEC JTC1 SC6 Seoul, Republic of Korea June, 2013

  4. Agenda • Overview of 6N15523 • Justification of TePA per 6N15523’s criteria • 6N15523’s analysis • Remote Configuration • AS in TePA versus AS in 802.1X • Significant Misunderstandings • Summary

  5. Overview of 6N15523 • Purpose is the promotion of TePA-based technologies and justification for their standardization • Attempts to demonstrate advantages and innovation when compared to existing technologies, namely 802.1X • Criteria used for comparison: • New security services • Higher security • Better performance • Significant difference of solution

  6. Overview of 6N11523 • Makes a series of false assertions and incorrect claims • Suffers from critical misunderstandings of technology • Misrepresentation of OCSP • Misstatements about peer authentication • Erroneous statements on protocol risks • Incorrectly equates the “AS” in 802.1X to the “AS” in TePA • Actually argues against standardization of TePA!

  7. Overview of 6N15523 • Incorrect “entity model” • “TLS is a two-entity security protocol, TePA a three-entity authentication protocol….The remote configuration of IEEE 802.1X and EAP-TLS extends to three entities.” • The number of entities is irrelevant, it is the functionality of entities in the deployment that matter • Misguided comparison • “In order to obtain useful results configurations with the same security claims should be compared” • To obtain useful results the security of similar configurations of the same deployment should be compared! • Analysis is from a misguided comparison using an incorrect model

  8. Overview of 6N15523 • Invalid assumptions, misguided comparison, and an incorrect model produce flawed conclusions: • “The co-located 802.1X configuration is less secure than TePA and has an important disadvantage in roaming situations due to the lack of a centralized authentication server.” • “TePAand the remote 802.1X configuration both are characterized by a centralized authentication server giving them the same trust requirements and roaming suitability.” • Summary does not evaluate the protocols according to criteria for evaluation listed in introduction.

  9. Agenda • Overview of 6N15523 • Justification of TePA per 6N15523’s criteria • 6N15523’s analysis • Remote Configuration • AS in TePA versus AS in 802.1X • Significant Misunderstandings • Summary

  10. New Security Services Beyond Existing Technology • TePA only supports certified public keys for both the client and server. • 802.1X supports numerous configurations • Client and server have certified public keys • Server has certified public key, client has password • Server has certified public key, client has biometric or smart card • Client and server use a pre-shared word, phrase, code or key • 802.1X supports optional deployments that allow all supported configurations to scale to large networks. • TePA provides a subset of services provided by existing technology, nothing new beyond what 802.1X offers

  11. Higher Security Than Existing Technology • TePA: • Performs an ISO 11770-3-like exchange using asymmetric key agreement that is authenticated with certified public keys • Uses on-line server for certificate status check • Provable security • 802.1X/EAP (in only configuration TePA supports): • Performs an ISO 11770-3-like exchange using asymmetric key agreement that is authenticated with certified public keys • Can use an on-line server for certificate status check • Provable security • TePA provides equivalent security and, given the cryptographic flexibility of 802.1X/EAP, arguably less security.

  12. Better Performance or Quality Than Existing Technology • The high pole in the tent of performance is the Diffie-Hellman and (EC)DSA calculations • In TePA, client and server perform 1 Diffie-Hellman, 1 signature, 2 verifications • In 802.1X/EAP-TLS with OCSP, client and server perform 1 Diffie-Hellman, 1 signature, 2 verifications • Quality is difficult to analyze since TePA is not fully-defined • What domain parameter sets are supported? • Can multiple security levels be supported? • TePA provides either comparable performance and quality versus existing technology, or it provides worse, depending on its complete specification.

  13. Significant Difference of Solution Than Existing Technology • TePA is significantly different in its rigidity– credentials must be certificates • The manner in which TePA performs an authenticated Diffie-Hellman, with on-line certificate status check is quite different • This difference has no practical effect on the protocol and how it addresses the problem • This is a highly subjective criterion of dubious benefit to protocol analysis.

  14. TePA Fails Justification • TePA fails to be justified by any of the four differentiators • TePA provides a subset of functionality provided by 802.1X • TePA provides similar security when deployed similarly, and arguably less since it cannot be deployed differently • Performance of TePA is comparable to 802.1X/EAP, quality is probably less due to TePA’s rigidity. • Differences between TePA and 802.1X, when similar deployments are compared similarly, are without distinction

  15. TePA Fails Justification • The flexibility in deployment of 802.1X/EAP is a significant advantage for 802.1X to the detriment of TePA • The experience in deployment of 802.1X over the past decade+ has not shown any problem solved by TePA • There is no reason to to consider unjustifiable alternatives to existing technology which works fine in practice

  16. Agenda • Overview of 6N15523 • Justification of TePA per 6N15523’s criteria • 6N15523’s analysis • Remote Configuration • AS in TePA versus AS in 802.1X • Significant Misunderstandings • Summary

  17. Analysis in 6N15523 • Comparative analysis is quite detailed • Pointless analysis of “remote configuration” in 802.1X • This sort of deployment is not possible with TePA • If “remote configuration” is required then TePA is inadequate, therefore end of analysis: TePA is not justified • If “remote configuration” is not required then why waste time on something that cannot be compared when the whole point is to compare the two technologies? • Some misunderstandings produce erroneous results • “AS” in TePA is not analogous to the “AS” in 802.1X • A certificate verified by an on-line notary does not provide authentication • Authentication in both TePA and EAP-TLS is through digital signatures by entities A and B • OCSP provides an on-line certificate status check

  18. Agenda • Overview of 6N15523 • Justification of TePA per 6N15523’s criteria • 6N15523’s analysis • Remote Configuration • AS in TePA versus AS in 802.1X • Significant Misunderstandings • Summary

  19. Remote Configuration • 6N15523 states, “the remote configuration [supported by 802.1X/EAP] has significant functional and management advantages in networks with multiple authenticators.” • Given: • Support for large networks is crucial • Large networks have multiple authenticators • TePA does not support “remote configuration” • Conclusion: • 802.1X/EAP has significant functional and management advantages over TePA • TePA is unable to support a crucial deployment model

  20. Agenda • Overview of 6N15523 • Justification of TePA per 6N15523’s criteria • 6N15523’s analysis • Remote Configuration • AS in TePA versus AS in 802.1X • Significant Misunderstandings • Summary

  21. Authentication Server in TePA • The TePA “Authentication Server” (AS) is not used for authentication of entities R (requestor) and C (controller) • Certificates are public data and are not secret • Anyone can present to the AS a valid certificate for which it does not possess the private key analog • The AS merely asserts the current status of the certificate • Authentication of R to C (C to R) is by way of a digital signature of R (C), verified using the public key from a trusted certificate

  22. AS in TePA does not perform Authentication Requester Controller AS Controller sends another entity’s certificate Message1, Cert-C Message 2, Cert-R, Sig-R Message 3, Cert-R, Cert-C Message 4, Cert-R, Cert-C, Res-R, Res-C, Sig-AS Message 5, Acc-R, RES, Sig-C Controller does not have the private analog to Cert-C, so signature verification fails! It’s a valid certificate so Res-C has status True

  23. Authentication Server in TePA • The AS does not, and cannot, discover the attack • The AS correctly noted that the certificate is valid • Authentication of C by R fails and the attack fails, no thanks the AS • The “AS” in 802.1X is analogous to the Controller in TePA • In TePA, Controller does DH, and generates and verifies a digital signature to authenticate the exchange • When used with 802.1X/EAP, the AS does DH, and generates and verifies digital signatures that authenticate the exchange • The “AS” in 802.1X, when used, terminates EAP • The “AS” in TePA is not functionally equivalent to the “AS” in 802.1x! • The AS in TePAdoes not provide the service of authentication • Any analysis that is based on an assertion to the contrary is therefore incorrect

  24. Agenda • Overview of 6N15523 • Justification of TePA per 6N15523’s criteria • 6N15523’s analysis • Remote Configuration • AS in TePA versus AS in 802.1X • Significant Misunderstandings • Summary

  25. Erroneous Claims • When using EAP-TLS “entity A [client] will not detect if entity B’s [server] certificate is invalid.” (section 4.5.1) • RFC 3546 states, “Constrained clients may wish to use a certificate-status protocol such as OCSP to check the validity of server certificates….” • Using the OCSP extension to TLS allows the client (“entity A”) to detect whether the server’s (“entity B’s”) certificate is valid or invalid; that is the whole point!

  26. Erroneous Claims (continued) • “The 802.1X configurations fail to prevent the use of invalid (expired or withdrawn) certificates by rogue entities.” (section6.1.2) • Expired certificates will fail normal certificate verification • The whole point of OCSP, and the OCSP extension to EAP-TLS, is to determine whether a certificate is withdrawn, i.e. revoked.

  27. Erroneous Claims (continued) • “In TePA entities A and B need only capability to verify C’s certificates and role, while in the 802.1X-based configurations entity A and B must be capable to verify each other’s certificates and role.” (section 6.1.2) • In both TePA and EAP-TLS the parties to the exchange must produce a digital signature and verify the other party’s digital signature– more than just trusting C. • In EAP-TLS the trust placed in a 3rd party (the CA) can be used to gain trust in the other entity’s certificate • A’s and B’s certificates must be verified otherwise the protocol is insecure, this is true for EAP-TLS and TePA

  28. Erroneous Claims (continued) • “A MITM can be mounted between entities A (client) and B (server) by an attacker holding verifying PKI certificates.” (section 4.5.2) • This is only possible if the certificate is not verified • This is possible when using TEPA-AC/KA4 too • This is not an attack against EAP-TLS, TEPA-AC/KA4, or any other authenticated key exchange, it’s sign of a poor implementation • EAP-TLS “cannot prevent this attack unless entity A (client) and B (server) know their identities in advance.” • The entities learn the identities to authenticate in-line. • The client knows to whom it is trying to connect, analogous to a browser issuing a warning on different server • Proper certificate verification prevents this • If A and B do not verify certificates in TePA (as is claimed) then it is susceptible to this attack, EAP-TLS is not.

  29. Erroneous Claims (continued) • “A rogue entity A (client) may gain unauthorized access to entity B (server) if…entity B does not request validation of entity A’s (client) certificate….” • If the server does not do a certificate status check then a revoked certificate can be used • The client’s certificate is still verified though, no rogue entity access is possible • The client still produces a CertificateVerify message which proves possession of the private analog to the public key in the (possibly revoked) certificate • Entity B may possess a current CRL: no validation request is necessary but rogue entity still does not gain access

  30. Erroneous Risks • It’s not a protocol risk if you must violate the protocol to be at risk! • “If B1 and B2 do not authenticate each other…” • “If entity A does not verify entity B’s certificate…” • “If validation requests are not authenticated…”

  31. Agenda • Overview of 6N15523 • Justification of TePA per 6N15523’s criteria • 6N15523’s analysis • Remote Configuration • AS in TePA versus AS in 802.1X • Significant Misunderstandings • Summary

  32. Summary • TePA fails to be justified by the criteria listed in 6N15523 • Security analysis in 6N15523, while quite good and very detailed, produces erroneous results based on misunderstandings of technology • 802.1X/EAP has world-wide deployment from small office to enterprise to multi-campus corporate environments to cross-continental, multi-service provider situations • There are no problems with 802.1X/EAP that are solved by switching to TePA • TePA severely constrains deployment options to the detriment of industry

  33. IEEE 802 Liason to ISO/IEC JTC1 SC6 Thanks!

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