TLS Working Group U. Blumenthal
Internet Draft P. Goel
Expires: January 2007 Intel Corporation
July 19, 2006
Pre-Shared Key Cipher Suite with NULL Encryption for
Transport Layer Security
draft-ietf-tls-psk-null-00.txt
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Abstract
This document specifies authentication-only cipher suites for the
Pre-Shared Key based [TLS-PSK] Transport Layer Security (TLS) [TLS]
protocol to support null encryption. These cipher suites are useful
for countries and places with cryptography-related restrictions.
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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].
Table of Contents
1. Introduction...................................................2
2. Cipher Usage...................................................2
3. Security Considerations........................................3
4. IANA Considerations............................................3
5. Acknowledgments................................................3
6. References.....................................................3
6.1. Normative References......................................3
Author's Addresses................................................4
Intellectual Property Statement...................................4
Disclaimer of Validity............................................5
Copyright Statement...............................................5
Acknowledgment....................................................5
1. Introduction
The RFC for Pre-Shared Key based TLS [TLS-PSK] specifies cipher
suites for supporting TLS using pre-shared symmetric keys. However
all the cipher suites defined in [TLS-PSK] require encryption. There
is a need for a cipher suite that supports no encryption. This is
required for implementations to meet import restrictions in some
countries. Even though no encryption is used, this cipher suite
supports authentication of the client and server to each other, and
message integrity. This document augments [TLS-PSK] by adding three
more cipher suites (PSK, DHE, RSA) with authentication and integrity
only - no encryption.
2. Cipher Usage
The new cipher suites proposed here is very similar to cipher suites
defined in [TLS-PSK], except that they define null encryption.
The cipher suites defined here uses the following options for key
exchange and hash part of the protocol:
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CipherSuite Key Exchange Cipher Hash
TLS_PSK_WITH_NULL_SHA PSK NULL SHA
TLS_DHE_PSK_WITH_NULL_SHA DHE_PSK NULL SHA
TLS_RSA_PSK_WITH_NULL_SHA RSA_PSK NULL SHA
For the meaning of the terms PSK please refer to section 1 in [TLS-
PSK]. For the meaning of the terms DHE and RSA please refer to
section 7.4.2 in [TLS].
3. Security Considerations
As with all schemes involving shared keys, special care should be
taken to protect the shared values and to limit their exposure over
time. As this document augments [TLS-PSK], everything stated in its
Security Consideration section applies here. In addition, as cipher
suites defined here do not support confidentiality - care should be
taken not to send confidential information (such as passwords) over
TLS-PSK connection with no encryption.
4. IANA Considerations
This document defines three new cipher suites, whose values are to be
assigned from the TLS Cipher Suite registry defined in [TLS].
CipherSuite TLS_PSK_WITH_NULL_SHA = { 0x00, 0xTBD1 };
CipherSuite TLS_DHE_PSK_WITH_NULL_SHA = { 0x00, 0xTBD2 };
CipherSuite TLS_RSA_PSK_WITH_NULL_SHA = { 0x00, 0xTBD3 };
5. Acknowledgments
The cipher suite defined in this document is an augmentation to and
based on [TLS-PSK].
6. References
6.1. Normative References
[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate
Requirement Levels", BCP 14, RFC 2119, March 1997.
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[TLS] Dierks, T. and Rescorla, E., "The TLS Protocol Version
1.1", RFC 4346, April 2006.
[TLS-PSK] Eronen, P., Tschofenig, H., "Pre-Shared Key CipherSuites
for Transport Layer Security (TLS)", RFC 4279, December
2005.
Author's Addresses
Uri Blumenthal
Intel Corporation
1515 State Route 10,
3PY1-3.536
Parsippany, NJ 07054
USA
Email: uri.blumenthal@intel.com
Purushottam Goel
Intel Corporation
2111 N.E. 25 Ave.
JF3-414
Hillsboro, OR 97124
USA
Email: Purushottam.goel@intel.com
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