DTN Research Group P. Lovell Internet-Draft SPARTA, Inc. Expires: April 29, 2009 October 26, 2008 DTN Bundle Metadata Confidentiality Specification draft-irtf-dtnrg-bundle-metadata-conf-00 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 April 29, 2009. Copyright Notice Copyright (C) The IETF Trust (2008). Lovell Expires April 29, 2009 [Page 1] Internet-Draft Metadata Confidentiality October 2008 Abstract This document describes a confidentiality ciphersuite for metadata in Delay-Tolerant Networking (DTN) Bundle Protocol (BP) bundles. Table of Contents 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 3 2. Storage Layout . . . . . . . . . . . . . . . . . . . . . . . . 4 3. CB-RSA-AES128-MB . . . . . . . . . . . . . . . . . . . . . . . 6 4. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 7 5. References . . . . . . . . . . . . . . . . . . . . . . . . . . 8 5.1. Normative References . . . . . . . . . . . . . . . . . . . 8 5.2. Informative References . . . . . . . . . . . . . . . . . . 8 Author's Address . . . . . . . . . . . . . . . . . . . . . . . . . 9 Intellectual Property and Copyright Statements . . . . . . . . . . 10 Lovell Expires April 29, 2009 [Page 2] Internet-Draft Metadata Confidentiality October 2008 1. Introduction 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]. This document defines a ciphersuite to protect metadata portions of a bundle. Bundles and the bundle protocol are described in [2]. Metadata blocks are described in [3] A bundle may contain one or more metadata blocks with information useful for routing and other decisions. In some scenarios it is necessary to prevent the metadata from being read in transit or at DTN nodes other than those authorized to do so. This ciphersuite is not for the direct use of the DTN bundle security protocol [4] since the confideniality described there is primarily for payload blocksand other security blocks related to the payload. Applying payload security to metadata will use the same key as the payload and this defeats most of the attractive characteristics we want. We therefore define a confidentiality suite that uses a different extension block type. Lovell Expires April 29, 2009 [Page 3] Internet-Draft Metadata Confidentiality October 2008 2. Storage Layout All extension blocks use the Canonical Bundle Block Format as defined in the Bundle Protocol Specification, and security blocks follow the Abstract Security Block layout shown in [4] Section 2.1. This block generally follows the Confidentiality Block description in Section 2.4 and Confidentiality ciphersuite #3 in Section 4.3, with exceptions and adjustments noted here. The layout is reproduced here (non-normative) for the convenience of readers, please refer to [4] for complete details. +----------------+----------------+----------------+----------------+ | type | flags (SDNV) | EID ref list(comp) | +----------------+----------------+----------------+----------------+ | length (SDNV) | +----------------+----------------+----------------+----------------+ | ciphersuite | correlator (SDNV) (optional) | +----------------+----------------+----------------+----------------+ |params len(SDNV)| ciphersuite params data | +----------------+----------------+----------------+----------------+ |res-len (SDNV) | security result data | +----------------+----------------+----------------+----------------+ The structure of an abstract security block Figure 1 Block type is 0x09. [needs conflict check] Ciphersuite flags indicate which fields are present in this block. EID references MUST be stored in the EID reference list. Security-source MAY be present. If not present, then the bundle- source is the security-source. Security-destination SHOULD be present. If not present, then the bundle-destination is the security-destination. In typical usage, the security-destination will be a logical group address of nodes which might be expected to use the metadata. Format of this group address is to be determined. Ciphersuite parameters and results are described in [4]. The following items will be present in ciphersuite parameters Lovell Expires April 29, 2009 [Page 4] Internet-Draft Metadata Confidentiality October 2008 1: initialization vector (IV) 7: C block salt 8: C block ICV The following items will be present in ciphersuite results 3: key information 13: encapsulated metadata block Lovell Expires April 29, 2009 [Page 5] Internet-Draft Metadata Confidentiality October 2008 3. CB-RSA-AES128-MB The CB-RSA-AES128-MB ciphersuite has ciphersuite ID value 0x004. This scheme encrypts metadata blocks of block type 0x08. The key size for this ciphersuite is 128 bits. Encryption is done using the AES algorithm in Galois/Counter Mode (GCM) as defined for ciphersuite #3 in [4] . The metadata block in the bundle is encrypted in its entirety using the key materials described in Section 2. The resultant ciphertext, plus the type and length, is placed into the security-result field of the C block. This C block then replaces the metadata block in the bundle. The key details are specified as key information (item type 2). The salt and IV items must be present in ciphersuite parameters. In normal usage, a node receiving a metadata block in encrypted form will decrypt the block and recover the metadata for its own purposes. If the block is forwarded then it SHOULD be in the as-received encrypted form, unless policy determines otherwise. The processing of the block from metadata to encrypted metadata is very similar to that performed on Payload Integrity Blocks in the standard Bundle Security Prototol, except that this blocks contains key information and there is no correlator. Lovell Expires April 29, 2009 [Page 6] Internet-Draft Metadata Confidentiality October 2008 4. IANA Considerations None at this time. If the bundle protocol becomes a standards track protocol, then we may want to consider having IANA establish a register of block types, and in particular for this specification a separate register of block formats. Lovell Expires April 29, 2009 [Page 7] Internet-Draft Metadata Confidentiality October 2008 5. References 5.1. Normative References [1] Bradner, S. and J. Reynolds, "Key words for use in RFCs to Indicate Requirement Levels", RFC 2119, October 1997. [2] Scott, K., "Bundle Protocol Specification", draft-irtf-dtnrg-bundle-spec-09.txt , April 2007. [3] Symington, S., "Delay-Tolerant Networking Metadata Extension Block", draft-irtf-dtnrg-bundle-metadata-block-00.txt , June 2007. [4] Symington, S., Farrell, S., Weiss, H., and P. Lovell, "Bundle Security Protocol Specification", draft-irtf-dtnrg-bundle-security-03.txt , March 2007. 5.2. Informative References [5] Cerf, V., "Delay-Tolerant Network Architecture", draft-irtf-dtnrg-arch-07.txt , October 2006, . [6] Farrell, S., Symington, S., and H. Weiss, "Delay-Tolerant Network Security Overview", draft-irtf-dtnrg-sec-overview-02.txt , October 2006. Lovell Expires April 29, 2009 [Page 8] Internet-Draft Metadata Confidentiality October 2008 Author's Address Peter Lovell SPARTA, Inc. 7110 Samuel Morse Drive Columbia, MD 21046 US Phone: +1-443-430-8052 Email: peter.lovell@sparta.com Lovell Expires April 29, 2009 [Page 9] Internet-Draft Metadata Confidentiality October 2008 Full Copyright Statement Copyright (C) The IETF Trust (2008). 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