< draft-camwinget-tls-ts13-macciphersuites-03.txt   draft-camwinget-tls-ts13-macciphersuites-04.txt >
TLS N. Cam-Winget TLS N. Cam-Winget
Internet-Draft Cisco Systems Internet-Draft Cisco Systems
Intended status: Informational J. Visoky Intended status: Informational J. Visoky
Expires: December 14, 2019 ODVA Expires: January 9, 2020 ODVA
June 12, 2019 July 8, 2019
TLS 1.3 Authentication and Integrity only Ciphersuites TLS 1.3 Authentication and Integrity only Ciphersuites
draft-camwinget-tls-ts13-macciphersuites-03 draft-camwinget-tls-ts13-macciphersuites-04
Abstract Abstract
There are use cases, specifically in Internet of Things (IoT) and There are use cases, specifically in Internet of Things (IoT) and
constrained environments that do not require confidentiality, though constrained environments that do not require confidentiality, though
mutual authentication during tunnel establishment and message mutual authentication during tunnel establishment and message
integrity is still mandated. This document defines the use of HMAC integrity is still mandated. This document defines the use of HMAC
only as ciphersuites in TLS 1.3. only as ciphersuites in TLS 1.3.
Status of This Memo Status of This Memo
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Internet-Drafts are working documents of the Internet Engineering Internet-Drafts are working documents of the Internet Engineering
Task Force (IETF). Note that other groups may also distribute Task Force (IETF). Note that other groups may also distribute
working documents as Internet-Drafts. The list of current Internet- working documents as Internet-Drafts. The list of current Internet-
Drafts is at https://datatracker.ietf.org/drafts/current/. Drafts is at https://datatracker.ietf.org/drafts/current/.
Internet-Drafts are draft documents valid for a maximum of six months Internet-Drafts are draft documents valid for a maximum of six months
and may be updated, replaced, or obsoleted by other documents at any and may be updated, replaced, or obsoleted by other documents at any
time. It is inappropriate to use Internet-Drafts as reference time. It is inappropriate to use Internet-Drafts as reference
material or to cite them other than as "work in progress." material or to cite them other than as "work in progress."
This Internet-Draft will expire on December 14, 2019. This Internet-Draft will expire on January 9, 2020.
Copyright Notice Copyright Notice
Copyright (c) 2019 IETF Trust and the persons identified as the Copyright (c) 2019 IETF Trust and the persons identified as the
document authors. All rights reserved. document authors. All rights reserved.
This document is subject to BCP 78 and the IETF Trust's Legal This document is subject to BCP 78 and the IETF Trust's Legal
Provisions Relating to IETF Documents Provisions Relating to IETF Documents
(https://trustee.ietf.org/license-info) in effect on the date of (https://trustee.ietf.org/license-info) in effect on the date of
publication of this document. Please review these documents publication of this document. Please review these documents
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include Simplified BSD License text as described in Section 4.e of include Simplified BSD License text as described in Section 4.e of
the Trust Legal Provisions and are provided without warranty as the Trust Legal Provisions and are provided without warranty as
described in the Simplified BSD License. described in the Simplified BSD License.
Table of Contents Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2
2. Terminology . . . . . . . . . . . . . . . . . . . . . . . . . 3 2. Terminology . . . . . . . . . . . . . . . . . . . . . . . . . 3
3. Applicability Statement . . . . . . . . . . . . . . . . . . . 3 3. Applicability Statement . . . . . . . . . . . . . . . . . . . 3
4. Using Integrity only Cipher Suites . . . . . . . . . . . . . 4 4. Using Integrity only Cipher Suites . . . . . . . . . . . . . 4
5. Record Payload Protection for Integrity only Cipher Suites . 4 5. Record Payload Protection for Integrity only Cipher Suites . 5
6. Key Schedule when using Integrity only Cipher Suites . . . . 5 6. Key Schedule when using Integrity only Cipher Suites . . . . 5
7. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 5 7. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 5
8. Security and Privacy Considerations . . . . . . . . . . . . . 5 8. Security and Privacy Considerations . . . . . . . . . . . . . 6
9. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 6 9. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 6
10. References . . . . . . . . . . . . . . . . . . . . . . . . . 6 10. References . . . . . . . . . . . . . . . . . . . . . . . . . 6
10.1. Normative References . . . . . . . . . . . . . . . . . . 6 10.1. Normative References . . . . . . . . . . . . . . . . . . 6
10.2. Informative Reference . . . . . . . . . . . . . . . . . 6 10.2. Informative Reference . . . . . . . . . . . . . . . . . 7
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 7 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 7
1. Introduction 1. Introduction
There are several use cases in which communications privacy is not There are several use cases in which communications privacy is not
strictly needed, although authenticity of the communications strictly needed, although authenticity of the communications
transport is still very important. For example, within the transport is still very important. For example, within the
Industrial Automation space there could be TCP or UDP communications Industrial Automation space there could be TCP or UDP communications
which command a robotic arm to move a certain distance at a certain which command a robotic arm to move a certain distance at a certain
speed. Without authenticity guarantees an attacker could modify the speed. Without authenticity guarantees an attacker could modify the
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information that can be exploited, it is generally just information information that can be exploited, it is generally just information
regarding the physical state of the system. At the same time, being regarding the physical state of the system. At the same time, being
able to modify this data would allow an attacker to either trigger able to modify this data would allow an attacker to either trigger
alarms falsely or to cover up evidence of an attack that might allow alarms falsely or to cover up evidence of an attack that might allow
for detection of their malicious activity. Furthermore, sensors are for detection of their malicious activity. Furthermore, sensors are
often low powered devices that might struggle to process encrypted often low powered devices that might struggle to process encrypted
and authenticated data. Sending data that is just authenticated and authenticated data. Sending data that is just authenticated
significantly eases the burden placed on these devices, yet still significantly eases the burden placed on these devices, yet still
allows the data to be protected against any tampering threats. allows the data to be protected against any tampering threats.
A fourth use case considers the protection of commands in the railway
industry. In railway control systems, no confidentiality
requirements are applied for the command exchange between an
interlocking controller and a railway equipment controller (for
instance, a railway point controller of a tram track where the
position of the controlled point is publicly available). However,
protecting integrity of those commands is vital, otherwise, an
adversary could change the target position of the point by modifying
the commands, which consequently could lead to the derailment of a
passing train. Furthermore, requirements for providing blackbox
recording of the safety related network traffic can only be fulfilled
through using integrity only ciphers, to be able to provide the
safety related commands to a third party, which is responsible for
the analysis after an accident.
The above use cases describe the relaxed requirements to provide The above use cases describe the relaxed requirements to provide
confidentiality, and as these devices come with a small runtime confidentiality, and as these devices come with a small runtime
memory footprint and reduced processing power, the need to minimize memory footprint and reduced processing power, the need to minimize
the number of cryptographic algorithms used is prioritized. the number of cryptographic algorithms used is prioritized.
4. Using Integrity only Cipher Suites 4. Using Integrity only Cipher Suites
This document defines the following cipher suites for use in TLS 1.3: This document defines the following cipher suites for use in TLS 1.3:
TLS_SHA256_SHA256 {0xC0, 0xB4} TLS_SHA256_SHA256 {0xC0, 0xB4}
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Given the lack of confidentiality, it is of the utmost importance Given the lack of confidentiality, it is of the utmost importance
that these cipher suites never be enabled by default. As these that these cipher suites never be enabled by default. As these
cipher suites are meant to serve the IoT market, it is important that cipher suites are meant to serve the IoT market, it is important that
any IoT endpoint that uses them be explicitly configured with a any IoT endpoint that uses them be explicitly configured with a
policy of non-confidential communications. policy of non-confidential communications.
9. Acknowledgements 9. Acknowledgements
The authors would like to acknowledge the work done by Industrial The authors would like to acknowledge the work done by Industrial
Communications Standards Groups (such as ODVA) as the motivation for Communications Standards Groups (such as ODVA) as the motivation for
this document. In addition, we are grateful for the advice and this document. We would also like to thank Steffen Fries for
feedback from Joe Salowey, Blake Anderson and David McGrew. providing a fourth use case. In addition, we are grateful for the
advice and feedback from Joe Salowey, Blake Anderson and David
McGrew.
10. References 10. References
10.1. Normative References 10.1. Normative References
[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate
Requirement Levels", BCP 14, RFC 2119, Requirement Levels", BCP 14, RFC 2119,
DOI 10.17487/RFC2119, March 1997, DOI 10.17487/RFC2119, March 1997,
<https://www.rfc-editor.org/info/rfc2119>. <https://www.rfc-editor.org/info/rfc2119>.
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