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authorDaniel Kubec <niel@rtfm.cz>2015-03-12 15:25:42 +0100
committerDavid Sommerseth <davids@redhat.com>2015-10-10 00:03:07 +0200
commit84604e0bae7216b46642d5a1a443b86f712d53aa (patch)
tree92b68790c2185e35e9bcada9434abb6212a0a12c
parent685e486e8b8f70c25f09590c24762ff734f94a51 (diff)
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Added document for TLS Keying Material Exporters [RFC-5705]
[DS: Fixed option prefix from '-' to '--'] Signed-off-by: Daniel Kubec <niel@rtfm.cz> Signed-off-by: David Sommerseth <davids@redhat.com> Acked-by: Steffan Karger <steffan.karger@fox-it.com Acked-by: David Sommerseth <davids@redhat.com>
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+OpenVPN Daniel Kubec <niel@rtfm.cz>
+RFC-5705 February 2015
+
+
+ Added support for TLS Keying Material Exporters
+
+Keying Material Exporter [RFC-5705] allow additional keying material to be
+derived from existing TLS channel. This exported keying material can then be
+used for a variety of purposes. TLS allows client and server to establish
+keying material for use in the upper layers between the TLS end-points and
+channel bindings is straightforward and well-defined mechanism how to
+authenticate other layers.
+
+
+OpenVPN Configuration
+
+--keying-material-exporter label len
+
+Export Keying Material [RFC-5705] of len bytes (min. 16 bytes) using label in
+environment (exported_keying_material) for use by plugins in
+OPENVPN_PLUGIN_TLS_FINAL callback.
+
+Note that exporter labels have the potential to collide with existing PRF
+labels. In order to prevent this, labels MUST begin with "EXPORTER".
+(This option requires OpenSSL 1.0.1 or newer.)
+
+
+Use Cases:
+
+Secure bindings of AAA information to application layer
+
+ OpenVPN Client <------> OpenVPN Server
+ [KeyAgreement] [KeyAgreement]
+
+ [TLSExportedKeyingMaterial] [TLSExportedKeyingMaterial]
+ [AAASessionKey] [AAASessionKey]
+ Client <------> Server
+ [Authenticated layer on top of (D)TLS]
+
+
+TLS side channel authentication and straightforward bindings of AAA information
+to application layer using well-defined mechanism.
+
+ OpenVPN Client <------> OpenVPN Server
+ [KeyAgreement] [KeyAgreement]
+
+ [TLSExportedKeyingMaterial] [TLSExportedKeyingMaterial]
+ [DerivedAAABindingKey] [DerivedAAABindingKey]
+ [AuthenticateBindingKeys]
+ Client -------> Server
+ [Confidental channel]
+
+
+TLS Message flow for a full handshake
+
+ ClientHello -------->
+ ServerHello
+ Certificate*
+ ServerKeyExchange*
+ CertificateRequest*
+ <-------- ServerHelloDone
+ Certificate*
+ ClientKeyExchange
+ CertificateVerify*
+ [ChangeCipherSpec]
+ Finished -------->
+ [ChangeCipherSpec]
+ <-------- Finished
+
+ GenerateTLSBindingKey GenerateTLSBindingKey
+
+ Application Data <-------> Application Data
+
+
+Terminology
+
+ AAA Authentication, Authorization, and Accounting:
+ functions that are generally required to control
+ access to a service and support auditing.
+
+ Secure channel a packet, datagram, octet stream connection, or
+ sequence of connections between two end-points that
+ affords cryptographic integrity and confidentiality
+ to data exchanged over it.
+
+ Channel binding the process of establishing that no man-in-the-middle
+ exists between two end-points that have been
+ authenticated using secure channel.
+
+ TLS Binding Key Exported Keying Material [RFC5705]
+
+ If no context is provided, it then computes:
+ PRF(SecurityParameters.master_secret, label,
+ SecurityParameters.client_random +
+ SecurityParameters.server_random
+ )[length]
+
+ If context is provided, it computes:
+ PRF(SecurityParameters.master_secret, label,
+ SecurityParameters.client_random +
+ SecurityParameters.server_random +
+ context_value_length + context_value
+ )[length]
+
+ AAA Binding Key TLS side channel authentication based on secure
+ channel bindings requires one more key derivation.
+
+ SHA1(TLSExportedKeyingMaterial + ServerPublicKey)
+
+Reference
+
+ [OPENAAA] "TLS side channel authentication and straightforward
+ bindings of AAA information to application
+ layer using well-defined mechanism."
+ Daniel Kubec <niel@rtfm.cz> March 2013
+ https://github.com/n13l/openaaa
+
+ [RFC5705] "Keying Material Exporters for TLS"
+ E. Rescorla, RFC 5705 March 2010
+ http://tools.ietf.org/html/rfc5705
+
+ [RFC5929] "Channel Bindings for TLS"
+ J. Altman, N. Williams, L. Zhu, RFC 5929, July 2010
+ http://tools.ietf.org/html/rfc5929
+
+ [RFC4680] "TLS Handshake Message for Supplemental Data"
+ S. Santesson, RFC 4680, September 2006
+ http://tools.ietf.org/html/rfc4680
+
+ [RFC5878] "TLS Authorization Extension"
+ M. Brown, R. Housley, RFC 5878, May 2010
+ http://tools.ietf.org/html/rfc5878
+
+ [RFC5746] "TLS Renegotiation Indication Extension"
+ E. Rescorla, M. Raym, S. Dispensa, N. Oskov
+ RFC 5746, February 2010
+ http://tools.ietf.org/html/rfc5746