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authorSimon Josefsson <simon@josefsson.org>2007-12-21 23:36:18 +0100
committerSimon Josefsson <simon@josefsson.org>2007-12-21 23:36:18 +0100
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treea04d732e33d18b37b10d2acbd13f01e6d792eed5 /doc
parent641a642f72e24abed1dbe32206e8b59d0318a904 (diff)
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+
+
+Network Working Group E. Rescorla
+Internet-Draft Network Resonance
+Intended status: Informational December 19, 2007
+Expires: June 21, 2008
+
+
+TLS Elliptic Curve Cipher Suites with SHA-256/384 and AES Galois Counter
+ Mode
+ draft-ietf-tls-ecc-new-mac-02.txt
+
+Status of this Memo
+
+ By submitting this Internet-Draft, each author represents that any
+ applicable patent or other IPR claims of which he or she is aware
+ have been or will be disclosed, and any of which he or she becomes
+ aware will be disclosed, in accordance with Section 6 of BCP 79.
+
+ Internet-Drafts are working documents of the Internet Engineering
+ Task Force (IETF), its areas, and its working groups. Note that
+ other groups may also distribute working documents as Internet-
+ Drafts.
+
+ Internet-Drafts are draft documents valid for a maximum of six months
+ and may be updated, replaced, or obsoleted by other documents at any
+ time. It is inappropriate to use Internet-Drafts as reference
+ material or to cite them other than as "work in progress."
+
+ The list of current Internet-Drafts can be accessed at
+ http://www.ietf.org/ietf/1id-abstracts.txt.
+
+ The list of Internet-Draft Shadow Directories can be accessed at
+ http://www.ietf.org/shadow.html.
+
+ This Internet-Draft will expire on June 21, 2008.
+
+Copyright Notice
+
+ Copyright (C) The IETF Trust (2007).
+
+Abstract
+
+ RFC 4492 describes elliptic curve cipher suites for Transport Layer
+ Security (TLS). However, all those cipher suites use SHA-1 as their
+ MAC algorithm. This document describes eight new CipherSuites for
+ TLS/DTLS which specify stronger digest algorithms. Four use HMAC
+ with SHA-256 or SHA-384 and four use AES in Galois Counter Mode
+ (GCM).
+
+
+
+
+Rescorla Expires June 21, 2008 [Page 1]
+
+Internet-Draft TLS ECC New MAC December 2007
+
+
+Table of Contents
+
+ 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 3
+ 1.1. Conventions Used In This Document . . . . . . . . . . . . . 3
+ 2. Cipher Suites . . . . . . . . . . . . . . . . . . . . . . . . . 3
+ 2.1. HMAC-based Cipher Suites . . . . . . . . . . . . . . . . . 3
+ 2.2. Galois Counter Mode-based Cipher Suites . . . . . . . . . . 4
+ 2.3. Acknowledgements . . . . . . . . . . . . . . . . . . . . . 5
+ 2.4. TLS Versions . . . . . . . . . . . . . . . . . . . . . . . 5
+ 2.5. Security Considerations . . . . . . . . . . . . . . . . . . 5
+ 2.5.1. Downgrade Attack . . . . . . . . . . . . . . . . . . . 5
+ 2.5.2. Perfect Forward Secrecy . . . . . . . . . . . . . . . . 6
+ 2.5.3. Counter Reuse with GCM . . . . . . . . . . . . . . . . 6
+ 2.6. IANA Considerations . . . . . . . . . . . . . . . . . . . . 6
+ 3. References . . . . . . . . . . . . . . . . . . . . . . . . . . 6
+ 3.1. Normative References . . . . . . . . . . . . . . . . . . . 6
+ 3.2. Informative References . . . . . . . . . . . . . . . . . . 7
+ Author's Address . . . . . . . . . . . . . . . . . . . . . . . . . 7
+ Intellectual Property and Copyright Statements . . . . . . . . . . 8
+
+
+
+
+
+
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+
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+
+
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+
+
+
+
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+
+
+
+
+
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+
+Rescorla Expires June 21, 2008 [Page 2]
+
+Internet-Draft TLS ECC New MAC December 2007
+
+
+1. Introduction
+
+ RFC 4492 [RFC4492] describes Elliptic Curve Cryptography (ECC) cipher
+ suites for Transport Layer Security (TLS). However, all of the RFC
+ 4492 suites use HMAC-SHA1 as their MAC algorithm. Due to recent
+ analytic work on SHA-1 [Wang05], the IETF is gradually moving away
+ from SHA-1 and towards stronger hash algorithms. This document
+ specifies TLS ECC cipher suites which replace SHA-256 and SHA-384
+ rather than SHA-1.
+
+ TLS 1.2 [I-D.ietf-tls-rfc4346-bis], adds support for authenticated
+ encryption with additional data (AEAD) cipher modes
+ [I-D.mcgrew-auth-enc]. This document also specifies a set of ECC
+ cipher suites using one such mode, Galois Counter Mode (GCM) [GCM].
+ Another document [I-D.salowey-tls-rsa-aes-gcm], provides support for
+ GCM with other key establishment methods.
+
+1.1. Conventions Used In This Document
+
+ The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
+ "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this
+ document are to be interpreted as described in [RFC2119].
+
+
+2. Cipher Suites
+
+ This document defines 8 new cipher suites to be added to TLS. All
+ use Elliptic Curve Cryptography for key exchange and digital
+ signature, as defined in RFC 4492.
+
+2.1. HMAC-based Cipher Suites
+
+ The first four cipher suites use AES [AES] in CBC [CBC] mode with an
+ HMAC-based MAC:
+
+ CipherSuite TLS_ECDHE_ECDSA_WITH_AES_128_CBC_SHA256 = {0xXX,XX};
+ CipherSuite TLS_ECDHE_ECDSA_WITH_AES_256_CBC_SHA384 = {0xXX,XX};
+ CipherSuite TLS_ECDH_ECDSA_WITH_AES_128_CBC_SHA256 = {0xXX,XX};
+ CipherSuite TLS_ECDH_ECDSA_WITH_AES_256_CBC_SHA384 = {0xXX,XX};
+
+ These four cipher suites are the same as the corresponding cipher
+ suites in RFC 4492 (TLS_ECDHE_ECDSA_WITH_AES_128_CBC_SHA,
+ TLS_ECDHE_ECDSA_WITH_AES_256_CBC_SHA,
+ TLS_ECDH_ECDSA_WITH_AES_128_CBC_SHA, and
+ TLS_ECDH_ECDSA_WITH_AES_256_CBC_SHA) except for the hash and PRF
+ algorithms, which are SHA-256 and SHA-384 [SHS] as follows.
+
+
+
+
+
+Rescorla Expires June 21, 2008 [Page 3]
+
+Internet-Draft TLS ECC New MAC December 2007
+
+
+ Cipher Suite MAC PRF
+ ------------ --- ---
+ TLS_ECDHE_ECDSA_WITH_AES_128_CBC_SHA256 HMAC-SHA-256 P_SHA-256
+ TLS_ECDHE_ECDSA_WITH_AES_256_CBC_SHA384 HMAC-SHA-384 P_SHA-384
+ TLS_ECDH_ECDSA_WITH_AES_128_CBC_SHA256 HMAC-SHA-256 P_SHA-256
+ TLS_ECDH_ECDSA_WITH_AES_256_CBC_SHA384 HMAC-SHA-384 P_SHA-384
+
+2.2. Galois Counter Mode-based Cipher Suites
+
+ The second four cipher suites use the new authenticated encryption
+ modes defined in TLS 1.2 with AES in Galois Counter Mode (GCM) [GCM]:
+
+ CipherSuite TLS_ECDHE_ECDSA_WITH_AES_128_GCM_SHA256 = {0xXX,XX};
+ CipherSuite TLS_ECDHE_ECDSA_WITH_AES_256_GCM_SHA384 = {0xXX,XX};
+ CipherSuite TLS_ECDH_ECDSA_WITH_AES_128_GCM_SHA256 = {0xXX,XX};
+ CipherSuite TLS_ECDH_ECDSA_WITH_AES_256_GCM_SHA384 = {0xXX,XX};
+
+ These cipher suites use authenticated encryption with additional data
+ algorithms AEAD_AES_128_GCM and AEAD_AES_256_GCM described in
+ [I-D.mcgrew-auth-enc]. The "nonce" input to the AEAD algorithm SHALL
+ be 12 bytes long, and is "partially implicit" (see Section 3.2.1 of
+ [I-D.mcgrew-auth-enc]). Part of the nonce is generated as part of
+ the handshake process and is static for the entire session and part
+ is carried in each packet.
+
+ struct {
+ opaque salt[4];
+ opaque explicit_nonce_part[8];
+ } GCMNonce.
+
+ The salt value is either the client_write_IV if the client is sending
+ or the server_write_IV if the server is sending. These IVs SHALL be
+ 4 bytes long.
+
+ The explicit_nonce_part is chosen by the sender and included in the
+ packet. Each value of the explicit_nonce_part MUST be distinct from
+ all other values, for any fixed key. Failure to meet this uniqueness
+ requirement can significantly degrade security. The
+ explicit_nonce_part is carried in the IV field of the
+ GenericAEADCipher structure. Therefore, for all the algorithms
+ defined in this section, SecurityParameters.iv_length=8.
+
+ In the case of TLS the counter MAY be the 64-bit sequence number. In
+ the case of Datagram TLS [RFC4347] [NOTE: there needs to be a new
+ DTLS draft for AEAD, this is a placeholder] the counter MAY be formed
+ from the concatenation of the 16-bit epoch with the 48-bit sequence
+ number.
+
+
+
+
+Rescorla Expires June 21, 2008 [Page 4]
+
+Internet-Draft TLS ECC New MAC December 2007
+
+
+ The PRF algorithms SHALL be as follows:
+
+ For TLS_ECDHE_ECDSA_WITH_AES_128_GCM_SHA256 and
+ TLS_ECDH_ECDSA_WITH_AES_128_GCM_SHA256 it SHALL be P_SHA-256.
+
+ For TLS_ECDHE_ECDSA_WITH_AES_128_GCM_SHA256 and
+ TLS_ECDH_ECDSA_WITH_AES_128_GCM_SHA256 it SHALL be P_SHA-384.
+
+2.3. Acknowledgements
+
+ This work was supported by the US Department of Defense.
+
+ David McGrew contributed substantual sections of the GCM nonce text
+ as well as providing a review of this document.
+
+2.4. TLS Versions
+
+ Because these cipher suites depend on features available only in TLS
+ 1.2 (PRF flexibility and combined authenticated encryption cipher
+ modes), they MUST NOT be negotiated by older versions of TLS.
+ Clients MUST NOT offer these cipher suites if they do not offer TLS
+ 1.2 or later. Servers which select an earlier version of TLS MUST
+ NOT select one of these cipher suites. Because TLS has no way for
+ the client to indicate that it supports TLS 1.2 but not earlier, a
+ non-compliant server might potentially negotiate TLS 1.1 or earlier
+ and select one of the cipher suites in this document. Clients MUST
+ check the TLS version and generate a fatal "illegal_parameter" alert
+ if they detect an incorrect version.
+
+2.5. Security Considerations
+
+ The security considerations in RFC 4346 and RFC 4492 apply to this
+ document as well. The remainder of this section describes security
+ considerations specific to the cipher suites described in this
+ document.
+
+2.5.1. Downgrade Attack
+
+ TLS negotiation is only as secure as the weakest cipher suite that is
+ supported. For instance, an implementation which supports both 160-
+ bit and 256-bit elliptic curves can be subject to an active downgrade
+ attack to the 160-bit security level. An attacker who can attack
+ that can then forge the Finished handshake check and successfully
+ mount a man-in-the-middle attack.
+
+
+
+
+
+
+
+Rescorla Expires June 21, 2008 [Page 5]
+
+Internet-Draft TLS ECC New MAC December 2007
+
+
+2.5.2. Perfect Forward Secrecy
+
+ The static ECDH cipher suites specified in this document do not
+ provide perfect forward secrecy (PFS). Thus, compromise of a single
+ static key leads to potential decryption of all traffic protected
+ using that key. Implementors of this specification SHOULD provide at
+ least one ECDHE mode of operation.
+
+2.5.3. Counter Reuse with GCM
+
+ AES-GCM is only secure if the counter is never reused. The IV
+ construction algorithm above is designed to ensure that this cannot
+ happen.
+
+2.6. IANA Considerations
+
+ IANA has assigned the following values for these cipher suites:
+
+ CipherSuite TLS_ECDHE_ECDSA_WITH_AES_128_CBC_SHA256 = {0xXX,XX};
+ CipherSuite TLS_ECDHE_ECDSA_WITH_AES_256_CBC_SHA384 = {0xXX,XX};
+ CipherSuite TLS_ECDH_ECDSA_WITH_AES_128_CBC_SHA256 = {0xXX,XX};
+ CipherSuite TLS_ECDH_ECDSA_WITH_AES_256_CBC_SHA384 = {0xXX,XX};
+ CipherSuite TLS_ECDHE_ECDSA_WITH_AES_128_GCM_SHA256 = {0xXX,XX};
+ CipherSuite TLS_ECDHE_ECDSA_WITH_AES_256_GCM_SHA384 = {0xXX,XX};
+ CipherSuite TLS_ECDH_ECDSA_WITH_AES_128_GCM_SHA256 = {0xXX,XX};
+ CipherSuite TLS_ECDH_ECDSA_WITH_AES_256_GCM_SHA384 = {0xXX,XX};
+
+
+3. References
+
+3.1. Normative References
+
+ [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate
+ Requirement Levels", BCP 14, RFC 2119, March 1997.
+
+ [RFC4492] Blake-Wilson, S., Bolyard, N., Gupta, V., Hawk, C., and B.
+ Moeller, "Elliptic Curve Cryptography (ECC) Cipher Suites
+ for Transport Layer Security (TLS)", RFC 4492, May 2006.
+
+ [RFC4347] Rescorla, E. and N. Modadugu, "Datagram Transport Layer
+ Security", RFC 4347, April 2006.
+
+ [I-D.mcgrew-auth-enc]
+ McGrew, D., "An Interface and Algorithms for Authenticated
+ Encryption", draft-mcgrew-auth-enc-05 (work in progress),
+ November 2007.
+
+ [I-D.ietf-tls-rfc4346-bis]
+
+
+
+Rescorla Expires June 21, 2008 [Page 6]
+
+Internet-Draft TLS ECC New MAC December 2007
+
+
+ Dierks, T. and E. Rescorla, "The Transport Layer Security
+ (TLS) Protocol Version 1.2", draft-ietf-tls-rfc4346-bis-07
+ (work in progress), November 2007.
+
+ [AES] National Institute of Standards and Technology,
+ "Specification for the Advanced Encryption Standard
+ (AES)", FIPS 197, November 2001.
+
+ [SHS] National Institute of Standards and Technology, "Secure
+ Hash Standard", FIPS 180-2, August 2002.
+
+ [CBC] National Institute of Standards and Technology,
+ "Recommendation for Block Cipher Modes of Operation -
+ Methods and Techniques", SP 800-38A, December 2001.
+
+ [GCM] National Institute of Standards and Technology,
+ "Recommendation for Block Cipher Modes of Operation:
+ Galois;/Counter Mode (GCM) for Confidentiality and
+ Authentication", SP 800-38D (DRAFT), April 2006.
+
+ [Wang05] Wang, X., Yin, Y., and H. Yu, "Finding Collisions in the
+ Full SHA-1", CRYPTO 2005, August 2005.
+
+3.2. Informative References
+
+ [I-D.salowey-tls-rsa-aes-gcm]
+ Salowey, J., "RSA based AES-GCM Cipher Suites for TLS",
+ draft-salowey-tls-rsa-aes-gcm-00 (work in progress),
+ February 2007.
+
+
+Author's Address
+
+ Eric Rescorla
+ Network Resonance
+ 2483 E. Bayshore #212
+ Palo Alto 94303
+ USA
+
+ Email: ekr@networkresonance.com
+
+
+
+
+
+
+
+
+
+
+
+Rescorla Expires June 21, 2008 [Page 7]
+
+Internet-Draft TLS ECC New MAC December 2007
+
+
+Full Copyright Statement
+
+ Copyright (C) The IETF Trust (2007).
+
+ This document is subject to the rights, licenses and restrictions
+ contained in BCP 78, and except as set forth therein, the authors
+ retain all their rights.
+
+ This document and the information contained herein are provided on an
+ "AS IS" basis and THE CONTRIBUTOR, THE ORGANIZATION HE/SHE REPRESENTS
+ OR IS SPONSORED BY (IF ANY), THE INTERNET SOCIETY, THE IETF TRUST AND
+ THE INTERNET ENGINEERING TASK FORCE DISCLAIM ALL WARRANTIES, EXPRESS
+ OR IMPLIED, INCLUDING BUT NOT LIMITED TO ANY WARRANTY THAT THE USE OF
+ THE INFORMATION HEREIN WILL NOT INFRINGE ANY RIGHTS OR ANY IMPLIED
+ WARRANTIES OF MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE.
+
+
+Intellectual Property
+
+ The IETF takes no position regarding the validity or scope of any
+ Intellectual Property Rights or other rights that might be claimed to
+ pertain to the implementation or use of the technology described in
+ this document or the extent to which any license under such rights
+ might or might not be available; nor does it represent that it has
+ made any independent effort to identify any such rights. Information
+ on the procedures with respect to rights in RFC documents can be
+ found in BCP 78 and BCP 79.
+
+ Copies of IPR disclosures made to the IETF Secretariat and any
+ assurances of licenses to be made available, or the result of an
+ attempt made to obtain a general license or permission for the use of
+ such proprietary rights by implementers or users of this
+ specification can be obtained from the IETF on-line IPR repository at
+ http://www.ietf.org/ipr.
+
+ The IETF invites any interested party to bring to its attention any
+ copyrights, patents or patent applications, or other proprietary
+ rights that may cover technology that may be required to implement
+ this standard. Please address the information to the IETF at
+ ietf-ipr@ietf.org.
+
+
+Acknowledgment
+
+ Funding for the RFC Editor function is provided by the IETF
+ Administrative Support Activity (IASA).
+
+
+
+
+
+Rescorla Expires June 21, 2008 [Page 8]
+
+
diff --git a/doc/protocol/draft-ietf-tls-extractor-00.txt b/doc/protocol/draft-ietf-tls-extractor-00.txt
new file mode 100644
index 0000000000..9c7dd50261
--- /dev/null
+++ b/doc/protocol/draft-ietf-tls-extractor-00.txt
@@ -0,0 +1,337 @@
+
+
+
+Network Working Group E. Rescorla
+Internet-Draft Network Resonance
+Intended status: Standards Track December 19, 2007
+Expires: June 21, 2008
+
+
+ Keying Material Extractors for Transport Layer Security (TLS)
+ draft-ietf-tls-extractor-00.txt
+
+Status of this Memo
+
+ By submitting this Internet-Draft, each author represents that any
+ applicable patent or other IPR claims of which he or she is aware
+ have been or will be disclosed, and any of which he or she becomes
+ aware will be disclosed, in accordance with Section 6 of BCP 79.
+
+ Internet-Drafts are working documents of the Internet Engineering
+ Task Force (IETF), its areas, and its working groups. Note that
+ other groups may also distribute working documents as Internet-
+ Drafts.
+
+ Internet-Drafts are draft documents valid for a maximum of six months
+ and may be updated, replaced, or obsoleted by other documents at any
+ time. It is inappropriate to use Internet-Drafts as reference
+ material or to cite them other than as "work in progress."
+
+ The list of current Internet-Drafts can be accessed at
+ http://www.ietf.org/ietf/1id-abstracts.txt.
+
+ The list of Internet-Draft Shadow Directories can be accessed at
+ http://www.ietf.org/shadow.html.
+
+ This Internet-Draft will expire on June 21, 2008.
+
+Copyright Notice
+
+ Copyright (C) The IETF Trust (2007).
+
+Abstract
+
+ A number of protocols wish to leverage Transport Layer Security (TLS)
+ to perform key establishment but then use some of the keying material
+ for their own purposes. This document describes a general mechanism
+ for allowing that.
+
+
+
+
+
+
+
+Rescorla Expires June 21, 2008 [Page 1]
+
+Internet-Draft TLS Extractors December 2007
+
+
+Table of Contents
+
+ 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 3
+ 2. Conventions Used In This Document . . . . . . . . . . . . . . . 3
+ 3. Signalling Extractors . . . . . . . . . . . . . . . . . . . . . 3
+ 4. Extractor Definition . . . . . . . . . . . . . . . . . . . . . 3
+ 5. Security Considerations . . . . . . . . . . . . . . . . . . . . 4
+ 6. IANA Considerations . . . . . . . . . . . . . . . . . . . . . . 4
+ 7. Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . . 5
+ 8. References . . . . . . . . . . . . . . . . . . . . . . . . . . 5
+ 8.1. Normative References . . . . . . . . . . . . . . . . . . . 5
+ 8.2. Informational References . . . . . . . . . . . . . . . . . 5
+ Author's Address . . . . . . . . . . . . . . . . . . . . . . . . . 5
+ Intellectual Property and Copyright Statements . . . . . . . . . . 6
+
+
+
+
+
+
+
+
+
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+Rescorla Expires June 21, 2008 [Page 2]
+
+Internet-Draft TLS Extractors December 2007
+
+
+1. Introduction
+
+ A number of protocols wish to leverage Transport Layer Security (TLS)
+ [4] or Datagram TLS (DTLS) [5] to perform key establishment but then
+ use some of the keying material for their own purposes. A typical
+ example is DTLS-SRTP [6], which uses DTLS to perform a key exchange
+ and negotiate the SRTP [3] protection suite and then uses the DTLS
+ master_secret to generate the SRTP keys.
+
+ These applications imply a need to be able to extract Exported Keying
+ Material (EKM) from TLS/DTLS. This mechanism has the following
+ requirements:
+
+ o Both client and server need to be able to extract the same EKM
+ value.
+ o EKM values should be indistinguishable from random by attackers
+ who don't know the master_secret.
+ o It should be possible to extract multiple EKM values from the same
+ TLS/DTLS association.
+ o Knowing one EKM value should not reveal any information about the
+ master_secret or about other EKM values.
+
+ The mechanism described in this document is intended to fill these
+ requirements.
+
+
+2. Conventions Used In This Document
+
+ The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
+ "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this
+ document are to be interpreted as described in [1].
+
+
+3. Signalling Extractors
+
+ Other protocols which wish to use extractors SHOULD have some way for
+ the peers to signal that an extractor will be used. An example is a
+ TLS extension, as used in DTLS-SRTP.
+
+
+4. Extractor Definition
+
+ An extractor takes as input two values:
+
+ o A disambiguating label string
+ o A length value
+
+ It then computes:
+
+
+
+Rescorla Expires June 21, 2008 [Page 3]
+
+Internet-Draft TLS Extractors December 2007
+
+
+ PRF(master_secret, label,
+ SecurityParameters.client_random +
+ SecurityParameters.server_random)[length]
+
+ The output is a pseudorandom bit string of length bytes generated
+ from the master_secret.
+
+ Label values MUST be registered via Specification Required as
+ described by RFC 2434 [2]. Note that extractor labels have the
+ potential to collide with existing PRF labels. In order to prevent
+ this, labels SHOULD begin with "EXTRACTOR". This is not a MUST
+ because there are existing uses which have labels which do not begin
+ with this prefix.
+
+
+5. Security Considerations
+
+ Because an extractor produces the same value if applied twice with
+ the same label to the same master_secret, it is critical that two EKM
+ values generated with the same label be used for two different
+ purposes--hence the requirement for IANA registration. However,
+ because extractors depend on the TLS PRF, it is not a threat to the
+ use of an EKM value generated from one label to reveal an EKM value
+ generated from another label.
+
+
+6. IANA Considerations
+
+ IANA is requested to create (has created) a TLS Extractor Label
+ registry for this purpose. The initial contents of the registry are
+ given below:
+
+ Value Reference
+ ----- ------------
+ client finished [RFC4346]
+ server finished [RFC4346]
+ master secret [RFC4346]
+ key expansion [RFC4346]
+ client EAP encryption [RFC2716]
+ ttls keying material [draft-funk-eap-ttls-v0-01]
+
+ Future values are allocated via RFC2434 Specification Required
+ policy. The label is a string consisting of printable ASCII
+ characters. IANA MUST also verify that one label is not a prefix of
+ any other label. For example, labels "key" or "master secretary" are
+ forbidden.
+
+
+
+
+
+Rescorla Expires June 21, 2008 [Page 4]
+
+Internet-Draft TLS Extractors December 2007
+
+
+7. Acknowledgments
+
+ Thanks to Pasi Eronen for valuable comments and the contents of the
+ IANA section.
+
+
+8. References
+
+8.1. Normative References
+
+ [1] Bradner, S., "Key words for use in RFCs to Indicate Requirement
+ Levels", BCP 14, RFC 2119, March 1997.
+
+ [2] Narten, T. and H. Alvestrand, "Guidelines for Writing an IANA
+ Considerations Section in RFCs", BCP 26, RFC 2434, October 1998.
+
+ [3] Baugher, M., McGrew, D., Naslund, M., Carrara, E., and K.
+ Norrman, "The Secure Real-time Transport Protocol (SRTP)",
+ RFC 3711, March 2004.
+
+ [4] Dierks, T. and E. Rescorla, "The Transport Layer Security (TLS)
+ Protocol Version 1.1", RFC 4346, April 2006.
+
+ [5] Rescorla, E. and N. Modadugu, "Datagram Transport Layer
+ Security", RFC 4347, April 2006.
+
+8.2. Informational References
+
+ [6] McGrew, D. and E. Rescorla, "Datagram Transport Layer Security
+ (DTLS) Extension to Establish Keys for Secure Real-time
+ Transport Protocol (SRTP)", draft-ietf-avt-dtls-srtp-01 (work in
+ progress), November 2007.
+
+
+Author's Address
+
+ Eric Rescorla
+ Network Resonance
+ 2064 Edgewood Drive
+ Palo Alto, CA 94303
+ USA
+
+ Email: ekr@networkresonance.com
+
+
+
+
+
+
+
+
+Rescorla Expires June 21, 2008 [Page 5]
+
+Internet-Draft TLS Extractors December 2007
+
+
+Full Copyright Statement
+
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+
+Rescorla Expires June 21, 2008 [Page 6]
+
+