--- 1/draft-ietf-tsvwg-dtls-for-sctp-00.txt 2009-07-08 19:12:07.000000000 +0200 +++ 2/draft-ietf-tsvwg-dtls-for-sctp-01.txt 2009-07-08 19:12:07.000000000 +0200 @@ -1,78 +1,88 @@ Network Working Group M. Tuexen Internet-Draft R. Seggelmann Intended status: Standards Track Muenster Univ. of Applied Sciences -Expires: April 25, 2009 E. Rescorla +Expires: January 9, 2010 E. Rescorla RTFM, Inc. - October 22, 2008 + July 8, 2009 Datagram Transport Layer Security for Stream Control Transmission Protocol - draft-ietf-tsvwg-dtls-for-sctp-00.txt + draft-ietf-tsvwg-dtls-for-sctp-01.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. + This Internet-Draft is submitted to IETF in full conformance with the + provisions of BCP 78 and 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 April 25, 2009. + This Internet-Draft will expire on January 9, 2010. + +Copyright Notice + + Copyright (c) 2009 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 in effect on the date of + publication of this document (http://trustee.ietf.org/license-info). + Please review these documents carefully, as they describe your rights + and restrictions with respect to this document. Abstract This document describes the usage of the Datagram Transport Layer Security (DTLS) protocol over the Stream Control Transmission Protocol (SCTP). The user of DTLS over SCTP can take advantage of all features provided by SCTP and its extensions, especially support of - o multiple streams to avoid head of line blocking. - o multi-homing to provide network level fault tolerance. + o multiple streams to avoid head of line blocking. + o unordered delivery. + o dynamic reconfiguration of streams. + o partially reliable data transfer. Table of Contents - 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 3 - 2. Conventions . . . . . . . . . . . . . . . . . . . . . . . . . . 4 - 3. DTLS considerations . . . . . . . . . . . . . . . . . . . . . . 4 - 4. SCTP considerations . . . . . . . . . . . . . . . . . . . . . . 5 - 5. IANA Considerations . . . . . . . . . . . . . . . . . . . . . . 6 - 6. Security Considerations . . . . . . . . . . . . . . . . . . . . 6 - 7. Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . . 6 - 8. References . . . . . . . . . . . . . . . . . . . . . . . . . . 6 - 8.1. Normative References . . . . . . . . . . . . . . . . . . . 6 - 8.2. Informative References . . . . . . . . . . . . . . . . . . 7 - Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 7 - Intellectual Property and Copyright Statements . . . . . . . . . . 8 + 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 4 + 2. Conventions . . . . . . . . . . . . . . . . . . . . . . . . . . 5 + 3. DTLS Considerations . . . . . . . . . . . . . . . . . . . . . . 5 + 4. SCTP Considerations . . . . . . . . . . . . . . . . . . . . . . 6 + 5. IANA Considerations . . . . . . . . . . . . . . . . . . . . . . 7 + 6. Security Considerations . . . . . . . . . . . . . . . . . . . . 7 + 7. Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . . 8 + 8. References . . . . . . . . . . . . . . . . . . . . . . . . . . 8 + 8.1. Normative References . . . . . . . . . . . . . . . . . . . 8 + 8.2. Informative References . . . . . . . . . . . . . . . . . . 8 + Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 8 1. Introduction 1.1. Overview This document describes the usage of the Datagram Transport Layer Security (DTLS) protocol, as defined in [RFC4347], over the Stream Control Transmission Protocol (SCTP), as defined in [RFC4960]. TLS is designed to run on top of a byte-stream oriented transport @@ -112,121 +122,149 @@ Connection: A TLS connection. Session: A TLS session. Stream: A unidirectional stream of an SCTP association. It is uniquely identified by a stream identifier. 1.3. Abbreviations - DTLS: Datagram Transport Layer Security + DTLS: Datagram Transport Layer Security. - MTU: Maximum Transmission Unit + MTU: Maximum Transmission Unit. - SCTP: Stream Control Transmission Protocol + PPID: Payload Protocol Identifier. - TCP: Transmission Control Protocol + SCTP: Stream Control Transmission Protocol. - TLS: Transport Layer Security + TCP: Transmission Control Protocol. + + TLS: Transport Layer Security. 2. Conventions 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]. -3. DTLS considerations +3. DTLS Considerations -3.1. Message sizes +3.1. Message Sizes - DTLS limits the user message size to the current Path MTU. This - limit SHOULD be increased to 2^14 Bytes for DTLS/SCTP. + DTLS limits the DTLS user message size to the current Path MTU minus + the header sizes. This limit SHOULD be increased to 2^14 Bytes for + DTLS over SCTP. -3.2. Message fragmentation +3.2. Message Fragmentation The DTLS layer MUST NOT perform message fragmentation. The SCTP layer will perform this task. Thus the supported maximum length of SCTP user messages MUST be at least 2^14 + 2048 + 5 = 18437 bytes. - Every DTLS message MUST be handled as one user message for SCTP. + Every DTLS message MUST be handled as one SCTP user message. -3.3. Replay detection +3.3. Replay Detection Replay detection of DTLS MUST NOT be used. 3.4. Path MTU Discovery Path MTU discovery of DTLS MUST NOT be used. 3.5. Retransmission of Messages DTLS procedures for retransmissions MUST NOT be used. -4. SCTP considerations +4. SCTP Considerations -4.1. Stream usage +4.1. Payload Protocol Identifier Usage - All DTLS control messages MUST be transported on stream 0 with - unlimited reliability and with the ordered delivery feature. + Application protocols running over DTLS over SCTP SHOULD register and + use a separate payload protocol identifier (PPID) and SHOULD NOT + reuse the PPID which they registered for running directly over SCTP. - User data messages MAY be transported over stream 0 but users SHOULD - use other streams for better performance. + This means in particular that there is no specific PPID for DTLS. -4.2. Chunk handling +4.2. Stream Usage + + All DTLS messages of the ChangeCipherSpec, Alert, or Handshake + protocol MUST be transported on stream 0 with unlimited reliability + and with the ordered delivery feature. + + All DTLS messages of the ApplicationData protocol MAY be transported + over stream 0 but users SHOULD use other streams for better + performance. + +4.3. Chunk Handling The DATA, SACK and FORWARD-TSN chunks of SCTP MUST be sent in an authenticated way as described in [RFC4895]. Other chunks MAY be sent in an authenticated way. This makes sure that an attacker can not modify the stream a message is sent in or affect the ordered/unordered delivery of the message. It is also not possible for an attacker to drop messages and use forged FORWARD-TSN and SACK chunks to hide this dropping. -4.3. Handshake +4.4. Handshake - To prevent DTLS from discarding user messages while renegotiating, - before sending a ClientHello all user messages MUST have been - acknowledged and can not be revoked anymore by the peer. + To prevent DTLS from discarding DTLS user messages while + renegotiating, before sending a ChangeCipherSpec message all + outstanding SCTP user messages MUST have been acknowledged by the + SCTP peer and MUST NOT be revoked anymore by the SCTP peer. - Prior to sending a HelloVerifyRequest, all user messages MUST be read - from the transport layer or user messages MUST be allowed during - handshake. + Prior to processing a received ChangeCipherSpec all other received + SCTP user messages which are buffered in the SCTP layer MUST be read + and processed by DTLS. -4.4. Handling of endpoint-pair shared secrets + User messages arriving between ChangeCipherSpec and Finished using + the new epoch have probably passed the Finished and MUST be buffered + by DTLS until the Finished is read. + +4.5. Handling of Endpoint-pair Shared Secrets The endpoint-pair shared secret for Shared Key Identifier 0 is empty. Whenever the master key changes, a 64 byte shared secret is derived from every master secret and provided as a new end-point pair shared secret by using the algorithm described in [I-D.ietf-tls-extractor]. The Shared Key Identifier MUST be incremented by 1. If it is 65535, the next value MUST be 1. Before sending the Finished message the active SCTP-AUTH key MUST be - switched to the new one. The Finished message MUST NOT be sent - before all messages except the ones from this handshake have been - acknowledged and can not be revoked anymore by the peer. + switched to the new one. Once the corresponding Finished message from the peer has been received the old key SHOULD be removed. +4.6. Shutdown + + To prevent DTLS from discarding DTLS user messages while shutting + down, before sending a CloseNotify message all outstanding SCTP user + messages MUST have been acknowledged by the SCTP peer and MUST NOT be + revoked anymore by the SCTP peer. + + Prior to processing a received CloseNotify all other received SCTP + user messages which are buffered in the SCTP layer MUST be read and + processed by DTLS. + 5. IANA Considerations - IANA needs to add a value to the TLS Extractor Label registry as + IANA needs to add a value to the TLS Exporter Label registry as described in [I-D.ietf-tls-extractor]. The label suggested is EXTRACTOR_DTLS_OVER_SCTP. The reference should refer to this document. 6. Security Considerations - This section is not complete yet. + This document does not add any additional security considerations in + addition to the ones given in [RFC4347] and [RFC4895]. 7. Acknowledgments The authors wish to thank Carsten Hohendorf, and Alfred Hoenes for their invaluable comments. 8. References 8.1. Normative References @@ -241,23 +279,23 @@ Security", RFC 4347, April 2006. [RFC4895] Tuexen, M., Stewart, R., Lei, P., and E. Rescorla, "Authenticated Chunks for the Stream Control Transmission Protocol (SCTP)", RFC 4895, August 2007. [RFC4960] Stewart, R., "Stream Control Transmission Protocol", RFC 4960, September 2007. [I-D.ietf-tls-extractor] - Rescorla, E., "Keying Material Extractors for Transport - Layer Security (TLS)", draft-ietf-tls-extractor-02 (work - in progress), September 2008. + Rescorla, E., "Keying Material Exporters for Transport + Layer Security (TLS)", draft-ietf-tls-extractor-05 (work + in progress), March 2009. 8.2. Informative References [RFC0793] Postel, J., "Transmission Control Protocol", STD 7, RFC 793, September 1981. [RFC3436] Jungmaier, A., Rescorla, E., and M. Tuexen, "Transport Layer Security over Stream Control Transmission Protocol", RFC 3436, December 2002. @@ -279,50 +317,10 @@ Email: seggelmann@fh-muenster.de Eric Rescorla RTFM, Inc. 2064 Edgewood Drive Palo Alto, CA 94303 USA Email: ekr@networkresonance.com - -Full Copyright Statement - - Copyright (C) The IETF Trust (2008). - - 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. 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