Recommendations for Secure Use of TLS and DTLS
draft-ietf-uta-tls-bcp-05

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Document Type Active Internet-Draft (uta WG)
Last updated 2014-10-13
Replaces draft-sheffer-tls-bcp
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UTA                                                           Y. Sheffer
Internet-Draft                                                  Porticor
Intended status: Best Current Practice                           R. Holz
Expires: April 17, 2015                                              TUM
                                                          P. Saint-Andre
                                                                    &yet
                                                        October 14, 2014

             Recommendations for Secure Use of TLS and DTLS
                       draft-ietf-uta-tls-bcp-05

Abstract

   Transport Layer Security (TLS) and Datagram Transport Security Layer
   (DTLS) are widely used to protect data exchanged over application
   protocols such as HTTP, SMTP, IMAP, POP, SIP, and XMPP.  Over the
   last few years, several serious attacks on TLS have emerged,
   including attacks on its most commonly used cipher suites and modes
   of operation.  This document provides recommendations for improving
   the security of deployed services that use TLS and DTLS.  The
   recommendations are applicable to the majority of use cases.

Status of This Memo

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   This Internet-Draft will expire on April 17, 2015.

Copyright Notice

   Copyright (c) 2014 IETF Trust and the persons identified as the
   document authors.  All rights reserved.

   This document is subject to BCP 78 and the IETF Trust's Legal
   Provisions Relating to IETF Documents
   (http://trustee.ietf.org/license-info) in effect on the date of

Sheffer, et al.          Expires April 17, 2015                 [Page 1]
Internet-Draft             TLS Recommendations              October 2014

   publication of this document.  Please review these documents
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   described in the Simplified BSD License.

Table of Contents

   1.  Introduction  . . . . . . . . . . . . . . . . . . . . . . . .   3
   2.  Intended Audience and Applicability Statement . . . . . . . .   4
     2.1.  Security Services . . . . . . . . . . . . . . . . . . . .   4
     2.2.  Unauthenticated TLS . . . . . . . . . . . . . . . . . . .   5
   3.  Conventions used in this document . . . . . . . . . . . . . .   5
   4.  General Recommendations . . . . . . . . . . . . . . . . . . .   6
     4.1.  Protocol Versions . . . . . . . . . . . . . . . . . . . .   6
       4.1.1.  SSL/TLS Protocol Versions . . . . . . . . . . . . . .   6
       4.1.2.  DTLS Protocol Versions  . . . . . . . . . . . . . . .   7
       4.1.3.  Fallback to Earlier Versions  . . . . . . . . . . . .   7
     4.2.  Strict TLS  . . . . . . . . . . . . . . . . . . . . . . .   7
     4.3.  Compression . . . . . . . . . . . . . . . . . . . . . . .   8
     4.4.  TLS Session Resumption  . . . . . . . . . . . . . . . . .   8
     4.5.  TLS Renegotiation . . . . . . . . . . . . . . . . . . . .   9
     4.6.  Server Name Indication  . . . . . . . . . . . . . . . . .   9
   5.  Recommendations: Cipher Suites  . . . . . . . . . . . . . . .   9
     5.1.  General Guidelines  . . . . . . . . . . . . . . . . . . .  10
     5.2.  Recommended Cipher Suites . . . . . . . . . . . . . . . .  11
     5.3.  Cipher Suite Negotiation Details  . . . . . . . . . . . .  11
     5.4.  Public Key Length . . . . . . . . . . . . . . . . . . . .  12
     5.5.  Modular vs. Elliptic Curve DH Cipher Suites . . . . . . .  12
     5.6.  Truncated HMAC  . . . . . . . . . . . . . . . . . . . . .  13
   6.  IANA Considerations . . . . . . . . . . . . . . . . . . . . .  13
   7.  Security Considerations . . . . . . . . . . . . . . . . . . .  13
     7.1.  Host Name Validation  . . . . . . . . . . . . . . . . . .  14
     7.2.  AES-GCM . . . . . . . . . . . . . . . . . . . . . . . . .  14
     7.3.  Forward Secrecy . . . . . . . . . . . . . . . . . . . . .  14
     7.4.  Diffie-Hellman Exponent Reuse . . . . . . . . . . . . . .  15
     7.5.  Certificate Revocation  . . . . . . . . . . . . . . . . .  16
   8.  Acknowledgments . . . . . . . . . . . . . . . . . . . . . . .  16
   9.  References  . . . . . . . . . . . . . . . . . . . . . . . . .  17
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