idnits 2.17.1 draft-birrane-dtn-sbsp-01.txt: Checking boilerplate required by RFC 5378 and the IETF Trust (see https://trustee.ietf.org/license-info): ---------------------------------------------------------------------------- No issues found here. Checking nits according to https://www.ietf.org/id-info/1id-guidelines.txt: ---------------------------------------------------------------------------- No issues found here. Checking nits according to https://www.ietf.org/id-info/checklist : ---------------------------------------------------------------------------- No issues found here. Miscellaneous warnings: ---------------------------------------------------------------------------- == The copyright year in the IETF Trust and authors Copyright Line does not match the current year -- The document date (October 16, 2015) is 3113 days in the past. Is this intentional? Checking references for intended status: Experimental ---------------------------------------------------------------------------- == Unused Reference: 'RFC5652' is defined on line 1813, but no explicit reference was found in the text == Unused Reference: 'RFC5751' is defined on line 1832, but no explicit reference was found in the text -- Obsolete informational reference (is this intentional?): RFC 5751 (Obsoleted by RFC 8551) Summary: 0 errors (**), 0 flaws (~~), 3 warnings (==), 2 comments (--). Run idnits with the --verbose option for more detailed information about the items above. -------------------------------------------------------------------------------- 2 Delay-Tolerant Networking E. Birrane 3 Internet-Draft JHU/APL 4 Intended status: Experimental J. Mayer 5 Expires: April 18, 2016 INSYEN AG 6 D. Iannicca 7 NASA GRC 8 October 16, 2015 10 Streamlined Bundle Security Protocol Specification 11 draft-birrane-dtn-sbsp-01 13 Abstract 15 This document defines a streamlined bundle security protocol, which 16 provides data authentication, integrity, and confidentiality services 17 for the Bundle Protocol. Capabilities are provided to protect blocks 18 in a bundle along a single path through a network. 20 Status of This Memo 22 This Internet-Draft is submitted in full conformance with the 23 provisions of BCP 78 and BCP 79. 25 Internet-Drafts are working documents of the Internet Engineering 26 Task Force (IETF). Note that other groups may also distribute 27 working documents as Internet-Drafts. The list of current Internet- 28 Drafts is at http://datatracker.ietf.org/drafts/current/. 30 Internet-Drafts are draft documents valid for a maximum of six months 31 and may be updated, replaced, or obsoleted by other documents at any 32 time. It is inappropriate to use Internet-Drafts as reference 33 material or to cite them other than as "work in progress." 35 This Internet-Draft will expire on April 18, 2016. 37 Copyright Notice 39 Copyright (c) 2015 IETF Trust and the persons identified as the 40 document authors. All rights reserved. 42 This document is subject to BCP 78 and the IETF Trust's Legal 43 Provisions Relating to IETF Documents 44 (http://trustee.ietf.org/license-info) in effect on the date of 45 publication of this document. Please review these documents 46 carefully, as they describe your rights and restrictions with respect 47 to this document. Code Components extracted from this document must 48 include Simplified BSD License text as described in Section 4.e of 50 Internet-DrafStreamlined Bundle Security Protocol Specifica October 2015 52 the Trust Legal Provisions and are provided without warranty as 53 described in the Simplified BSD License. 55 Table of Contents 57 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 3 58 1.1. Related Documents . . . . . . . . . . . . . . . . . . . . 3 59 1.2. Terminology . . . . . . . . . . . . . . . . . . . . . . . 4 60 2. Key Properties . . . . . . . . . . . . . . . . . . . . . . . 6 61 2.1. Block-Level Granularity . . . . . . . . . . . . . . . . . 6 62 2.2. Multiple Security Sources . . . . . . . . . . . . . . . . 7 63 2.3. Single Security Destinations . . . . . . . . . . . . . . 7 64 2.4. Mixed Security Policy . . . . . . . . . . . . . . . . . . 8 65 2.5. User-Selected Ciphersuites . . . . . . . . . . . . . . . 8 66 2.6. Deterministic Processing . . . . . . . . . . . . . . . . 8 67 3. Security Block Definitions . . . . . . . . . . . . . . . . . 9 68 3.1. Block Identification . . . . . . . . . . . . . . . . . . 10 69 3.2. Abstract Security Block . . . . . . . . . . . . . . . . . 11 70 3.3. Block Ordering . . . . . . . . . . . . . . . . . . . . . 14 71 3.4. Bundle Authentication Block . . . . . . . . . . . . . . . 15 72 3.5. Block Integrity Block . . . . . . . . . . . . . . . . . . 16 73 3.6. Block Confidentiality Block . . . . . . . . . . . . . . . 17 74 3.7. Cryptographic Message Syntax Block . . . . . . . . . . . 19 75 3.8. Block Interactions . . . . . . . . . . . . . . . . . . . 20 76 3.9. Parameters and Result Fields . . . . . . . . . . . . . . 22 77 3.10. BSP Block Example . . . . . . . . . . . . . . . . . . . . 24 78 4. Security Processing . . . . . . . . . . . . . . . . . . . . . 27 79 4.1. Canonical Forms . . . . . . . . . . . . . . . . . . . . . 27 80 4.1.1. Bundle Canonicalization . . . . . . . . . . . . . . . 27 81 4.1.2. Block Canonicalization . . . . . . . . . . . . . . . 28 82 4.1.3. Considerations . . . . . . . . . . . . . . . . . . . 31 83 4.2. Endpoint ID Confidentiality . . . . . . . . . . . . . . . 32 84 4.3. Bundles Received from Other Nodes . . . . . . . . . . . . 32 85 4.3.1. Receiving BAB Blocks . . . . . . . . . . . . . . . . 32 86 4.3.2. Receiving BCB Blocks . . . . . . . . . . . . . . . . 33 87 4.3.3. Receiving BIB Blocks . . . . . . . . . . . . . . . . 33 88 4.4. Receiving CMSB Blocks . . . . . . . . . . . . . . . . . . 34 89 4.5. Bundle Fragmentation and Reassembly . . . . . . . . . . . 34 90 4.6. Reactive Fragmentation . . . . . . . . . . . . . . . . . 35 91 5. Key Management . . . . . . . . . . . . . . . . . . . . . . . 35 92 6. Policy Considerations . . . . . . . . . . . . . . . . . . . . 35 93 7. Security Considerations . . . . . . . . . . . . . . . . . . . 36 94 8. Conformance . . . . . . . . . . . . . . . . . . . . . . . . . 37 95 9. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 37 96 9.1. Bundle Block Types . . . . . . . . . . . . . . . . . . . 37 97 9.2. Cipher Suite Flags . . . . . . . . . . . . . . . . . . . 37 98 9.3. Parameters and Results . . . . . . . . . . . . . . . . . 38 99 10. References . . . . . . . . . . . . . . . . . . . . . . . . . 39 101 Internet-DrafStreamlined Bundle Security Protocol Specifica October 2015 103 10.1. Normative References . . . . . . . . . . . . . . . . . . 39 104 10.2. Informative References . . . . . . . . . . . . . . . . . 39 105 Appendix A. Acknowledgements . . . . . . . . . . . . . . . . . . 40 106 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 40 108 1. Introduction 110 This document defines security features for the Bundle Protocol 111 [RFC5050] intended for use in delay-tolerant networks, in order to 112 provide Delay-Tolerant Networking (DTN) security services. 114 The Bundle Protocol is used in DTNs that overlay multiple networks, 115 some of which may be challenged by limitations such as intermittent 116 and possibly unpredictable loss of connectivity, long or variable 117 delay, asymmetric data rates, and high error rates. The purpose of 118 the Bundle Protocol is to support interoperability across such 119 stressed networks. 121 The stressed environment of the underlying networks over which the 122 Bundle Protocol operates makes it important for the DTN to be 123 protected from unauthorized use, and this stressed environment poses 124 unique challenges for the mechanisms needed to secure the Bundle 125 Protocol. Furthermore, DTNs may be deployed in environments where a 126 portion of the network might become compromised, posing the usual 127 security challenges related to confidentiality, integrity, and 128 availability. 130 This document describes the Streamlined Bundle Security Protocol 131 (SBSP), which provides security services for blocks within a bundle 132 from the bundle source to the bundle destination. Specifically, the 133 SBSP provides authentication, integrity, and confidentiality for 134 bundles along a path through a DTN. 136 SBSP applies, by definition, only to those nodes that implement it, 137 known as "security-aware" nodes. There MAY be other nodes in the DTN 138 that do not implement SBSP. All nodes can interoperate with the 139 exception that SBSP security operations can only happen at SBSP 140 security-aware nodes. 142 1.1. Related Documents 144 This document is best read and understood within the context of the 145 following other DTN documents: 147 "Delay-Tolerant Networking Architecture" [RFC4838] defines the 148 architecture for delay-tolerant networks, but does not discuss 149 security at any length. 151 Internet-DrafStreamlined Bundle Security Protocol Specifica October 2015 153 The DTN Bundle Protocol [RFC5050] defines the format and processing 154 of the blocks used to implement the Bundle Protocol, excluding the 155 security-specific blocks defined here. 157 The Bundle Security Protocol [RFC6257] introduces the concepts of 158 security blocks for authentication, confidentiality, and integrity. 159 The SBSP is based off of this document. 161 1.2. Terminology 163 The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", 164 "SHOULD", "SHOULD NOT", "RECOMMENDED", "NOT RECOMMENDED", "MAY", and 165 "OPTIONAL" in this document are to be interpreted as described in 166 [RFC2119]. 168 We introduce the following terminology for purposes of clarity. 170 o Source - the bundle node from which a bundle originates. 172 o Destination - the bundle node to which a bundle is ultimately 173 destined. 175 o Forwarder - the bundle node that forwarded the bundle on its most 176 recent hop. 178 o Intermediate Receiver, Waypoint, or "Next Hop" - the neighboring 179 bundle node to which a forwarder forwards a bundle. 181 o Path - the ordered sequence of nodes through which a bundle passes 182 on its way from source to destination. The path is not 183 necessarily known by the bundle, or any bundle-aware nodes. 185 Figure 1 below is adapted from [RFC5050] and shows four bundle nodes 186 (denoted BN1, BN2, BN3, and BN4) that reside above some transport 187 layer(s). Three distinct transport and network protocols (denoted 188 T1/N1, T2/N2, and T3/N3) are also shown. 190 Internet-DrafStreamlined Bundle Security Protocol Specifica October 2015 192 +---------v-| +->>>>>>>>>>v-+ +->>>>>>>>>>v-+ +-^---------+ 193 | BN1 v | | ^ BN2 v | | ^ BN3 v | | ^ BN4 | 194 +---------v-+ +-^---------v-+ +-^---------v-+ +-^---------+ 195 | T1 v | + ^ T1/T2 v | + ^ T2/T3 v | | ^ T3 | 196 +---------v-+ +-^---------v-+ +-^---------v + +-^---------+ 197 | N1 v | | ^ N1/N2 v | | ^ N2/N3 v | | ^ N3 | 198 +---------v-+ +-^---------v + +-^---------v-+ +-^---------+ 199 | >>>>>>>>^ >>>>>>>>>>^ >>>>>>>>^ | 200 +-----------+ +------------+ +-------------+ +-----------+ 201 | | | | 202 |<-- An Internet --->| |<--- An Internet --->| 203 | | | | 205 Figure 1: Bundle Nodes Sit at the Application Layer of the Internet 206 Model 208 BN1 originates a bundle that it forwards to BN2. BN2 forwards the 209 bundle to BN3, and BN3 forwards the bundle to BN4. BN1 is the source 210 of the bundle and BN4 is the destination of the bundle. BN1 is the 211 first forwarder, and BN2 is the first intermediate receiver; BN2 then 212 becomes the forwarder, and BN3 the intermediate receiver; BN3 then 213 becomes the last forwarder, and BN4 the last intermediate receiver, 214 as well as the destination. 216 If node BN2 originates a bundle (for example, a bundle status report 217 or a custodial signal), which is then forwarded on to BN3, and then 218 to BN4, then BN2 is the source of the bundle (as well as being the 219 first forwarder of the bundle) and BN4 is the destination of the 220 bundle (as well as being the final intermediate receiver). 222 We introduce the following security-specific DTN terminology. 224 o Security-Service - the security features supported by this 225 specification: authentication, integrity, and confidentiality. 227 o Security-Source - a bundle node that adds a security block to a 228 bundle. 230 o Security-Destination - a bundle node that evaluates a security 231 block from a bundle. When a security-service is applied hop-by- 232 hop, the security-destination is the next intermediate receiver. 233 Otherwise, the security-destination is the same as the bundle 234 destination. 236 o Security-Target - the portion of a bundle (e.g., the primary 237 block, payload block, extension block, or entire bundle) that 238 receives a security-service as part of a security-operation. 240 Internet-DrafStreamlined Bundle Security Protocol Specifica October 2015 242 o Security Block - a single instance of a SBSP extension block in a 243 bundle. 245 o Security-Operation - the application of a security-service to a 246 specific security-target, notated as OP(security-service, 247 security-target). For example, OP(authentication, bundle) or 248 OP(confidentiality, payload). Every security-operation in a 249 bundle MUST be unique, meaning that a security-service can only be 250 applied to a security-target once in a bundle. A security- 251 operation MAY be implemented by one or more security blocks. 253 2. Key Properties 255 The application of security services in a DTN is a complex endeavor 256 that must consider physical properties of the network, policies at 257 each node, and various application security requirements. Rather 258 than enumerate all potential security implementations in all 259 potential DTN topologies, this specification defines a set of key 260 properties of a security system. The security primitives outlined in 261 this document MUST enable the realization of these properties in a 262 DTN deploying the Bundle Protocol. 264 2.1. Block-Level Granularity 266 Blocks within a bundle represent different types of information. The 267 primary block contains identification and routing information. The 268 payload block carries application data. Extension blocks carry a 269 variety of data that may augment or annotate the payload, or 270 otherwise provide information necessary for the proper processing of 271 a bundle along a path. Therefore, applying a single level and type 272 of security across an entire bundle fails to recognize that blocks in 273 a bundle may represent different types of information with different 274 security needs. 276 Security services within this specification MUST provide block level 277 granularity where applicable such that different blocks within a 278 bundle may have different security services applied to them. 280 For example, within a bundle, a payload might be encrypted to protect 281 its contents, whereas an extension block containing summary 282 information related to the payload might be integrity signed but 283 otherwise unencrypted to provide certain nodes access to payload- 284 related data without providing access to the payload. 286 Internet-DrafStreamlined Bundle Security Protocol Specifica October 2015 288 2.2. Multiple Security Sources 290 The Bundle Protocol allows extension blocks to be added to a bundle 291 at any time during its existence in the DTN. When a waypoint node 292 adds a new extension block to a bundle, that extension block may have 293 security services applied to it by that waypoint. Similarly, a 294 waypoint node may add a security service to an existing extension 295 block, consistent with its security policy. For example, a node 296 representing a boundary between a trusted part of the network and an 297 untrusted part of the network may wish to apply payload encryption 298 for bundles leaving the trusted portion of the network. 300 In each case, a node other than the bundle originator may be adding a 301 security service to the bundle and, as such, the source for the 302 security service will be different than the source of the bundle 303 itself. Security services MUST track their orginating node so as to 304 properly apply policy and key selection associated with processing 305 the security service at the bundle destination. 307 Referring to Figure 1, if the bundle that originates at BN1 is given 308 security blocks by BN1, then BN1 is the security-source for those 309 blocks as well as being the source of the bundle. If the bundle that 310 originates at BN1 is then given a security block by BN2, then BN2 is 311 the security-source for that block even though BN1 remains the bundle 312 source. 314 A bundle MAY have multiple security blocks and these blocks MAY have 315 different security-sources. Each security block in a bundle will be 316 associated with a specific security-operation. All security blocks 317 comprising a security-operation MUST have the same security-source 318 and security-destination. 320 As required in [RFC5050], forwarding nodes MUST transmit blocks in a 321 bundle in the same order in which they were received. This 322 requirement applies to all DTN nodes, not just ones that implement 323 security processing. Blocks in a bundle MAY be added or deleted 324 according to the applicable specification, but those blocks that are 325 both received and transmitted MUST be transmitted in the same order 326 that they were received. 328 2.3. Single Security Destinations 330 The destination of all security blocks in a bundle MUST be the bundle 331 destination, with the exception of authentication security blocks, 332 whose destination is the next hop along the bundle path. In a DTN, 333 there is typically no guarantee that a bundle will visit a particular 334 intermediate receiver during its journey, or that a particular series 335 of intermediate receivers will be visited in a particular order. 337 Internet-DrafStreamlined Bundle Security Protocol Specifica October 2015 339 Security-destinations different from bundle destinations would place 340 a tight (and possibly intractable) coupling between security and 341 routing services in an overlay network. 343 2.4. Mixed Security Policy 345 Different nodes in a DTN may have different security-related 346 capabilities. Some nodes may not be security-aware and will not 347 understand any security-related extension blocks. Other nodes may 348 have security policies that require evaluation of security services 349 at places other than the bundle destination (such as verifying 350 integrity signatures at certain waypoint nodes). Other nodes may 351 ignore any security processing if they are not the destination of the 352 bundle. The security services described in this specification must 353 allow each of these scenarios. 355 Extension blocks representing security services MUST have their block 356 processing flags set such that the block (and bundle, where 357 applicable) will be treated appropriately by non-security-aware 358 nodes. 360 Extension blocks providing integrity and authentication services 361 within a bundle MUST support options to allow waypoint nodes to 362 evaluate these signatures if such nodes have the proper configuraton 363 to do so. 365 2.5. User-Selected Ciphersuites 367 The security services defined in this specification rely on a a 368 variety of ciphersuites providing integrity signatures, ciphertext, 369 and other information necessary to populate security blocks. Users 370 may wish to select differing ciphersuites to implement different 371 security services. For example, some users may wish to use a SHA-1 372 based hash for integrity whereas other users may require a SHA-2 hash 373 instead. The security services defined in this specification MUST 374 provide a mechanism for identifying what ciphersuite has been used to 375 populate a security block. 377 2.6. Deterministic Processing 379 In all cases, the processing order of security services within a 380 bundle must avoid ambiguity when evaluating security at the bundle 381 destination. This specification MUST provide determinism in the 382 application and evaluation of security services, even when doing so 383 results in a loss of flexibility. 385 Internet-DrafStreamlined Bundle Security Protocol Specifica October 2015 387 3. Security Block Definitions 389 There are four types of security blocks that MAY be included in a 390 bundle. These are the Bundle Authentication Block (BAB), the Block 391 Integrity Block (BIB), the Block Confidentiality Block (BCB), and the 392 Cryptographic Messaging Syntax Block (CMSB). 394 The BAB is used to ensure the authenticity and integrity of the 395 bundle along a single hop from forwarder to intermediate receiver. 396 As such, BABs operate between topologically adjacent nodes. 397 Security-aware nodes MAY choose to require BABs from a given 398 neighbor in the network in order to receive and process a received 399 bundle. 401 The BIB is used to ensure the authenticity and integrity of its 402 security-target from the BIB security-source, which creates the 403 BIB, to the bundle destination, which verifies the BIB 404 authenticator. The authentication information in the BIB MAY 405 (when possible) be verified by any node in between the BIB 406 security-source and the bundle destination. 408 The BCB indicates that the security-target has been encrypted, in 409 whole or in part, at the BCB security-source in order to protect 410 its content while in transit to the bundle destination. 412 The CMSB contains a Cryptographic Message Syntax (CMS) payload 413 used to describe a security service applied to another extension 414 block. NOTE: Applications may choose to simply place CMS text as 415 the payload to the bundle. In such cases, security is considered 416 to be implemented at the application layer and CMSBs are not 417 required in that case. 419 Certain cipher suites may allow or require multiple instances of a 420 block to appear in the bundle. For example, an authentication cipher 421 suite may require two security blocks, one before the payload block 422 and one after. Despite the presence of two security blocks, they 423 both comprise the same security-operation - OP(authentication,bundle) 424 in this example. 426 A security-operation MUST NOT be applied more than once in a bundle. 427 For example, the two security-operations: OP(integrity, payload) and 428 OP(integrity, payload) are considered redundant and MUST NOT appear 429 together in a bundle. However, the two security operations 430 OP(integrity, payload) and OP(integrity, extension_block_1) MAY both 431 be present in the bundle. Also, the two security operations 432 OP(integrity, extension_block_1) and OP(integrity, extension_block_2) 433 are unique and may both appear in the same bundle. 435 Internet-DrafStreamlined Bundle Security Protocol Specifica October 2015 437 Many of the fields in these block definitions use the Self-Delimiting 438 Numeric Value (SDNV) type whose format and encoding is as defined in 439 [RFC5050]. 441 3.1. Block Identification 443 This specification requires that every target block of a security 444 operation be uniquely identifiable. In cases where there can only be 445 a single instance of a block in the bundle (as is the case with the 446 primary block and the payload block) then the unique identifier is 447 simply the block type. These blocks are described as "singleton 448 blocks". It is possible that a bundle may contain multiple instances 449 of a block type. In such a case, each instance of the block type 450 must be uniquely identifiable and the block type itself is not 451 sufficient for this identification. These blocks are described as 452 "non-singleton blocks". 454 The definition of the extension block header from [RFC5050] does not 455 provide additional identifying information for a block beyond the 456 block type. The addition of an occurrence number to the block is 457 necessary to identify the block instance in the bundle. This section 458 describes the use of an Artificial EID (AEID) reference in a block 459 header to add unique identification for non-singleton blocks. 461 Figure 7 of [RFC5050] illustrates that an EID reference in a block 462 header is the 2-tuple of the reference scheme and the reference 463 scheme specific part (SSP), each of which are encoded as SDNVs. The 464 AEID MUST encode the occurrence number in the reference scheme SDNV 465 and MUST set the reference SSP to 0. A reference SSP value of 0 is 466 an invalid offset for an SSP in the bundle dictionary and, therefore, 467 the use of 0 in this field identifies the reference as an AEID. 469 The occurrence number MAY be any positive value that is not already 470 present as an occurrence number for the same block type in the 471 bundle. These numbers are independent of relative block position 472 within the bundle, and whether blocks of the same type have been 473 added or removed from the bundle. Once an AEID has been added to a 474 block instance, it MUST NOT be changed until all security operations 475 that target the block instance have been removed from the bundle. 477 If a node wishes to apply a security operation to a target block it 478 MUST determine whether the target block is a singleton block or a 479 non-singleton block. If the target block is non-singleton, then the 480 node MUST find the AEID for the target. If an AEID is not present in 481 the target block header then the node MAY choose to either cancel the 482 security operation or add an AEID to the block, in accordance with 483 security policy. 485 Internet-DrafStreamlined Bundle Security Protocol Specifica October 2015 487 If a node chooses to add an AEID to a target block header it MUST 488 perform the following activities. 490 o The "Block contains an EID reference field" flag MUST be set for 491 the target block, if it is not already set. 493 o The EID reference count for the block MUST be updated to reflect 494 the addition of the AEID. 496 o The scheme offset of the AEID MUST be a value greater than 0. The 497 scheme offset MUST NOT be the same as any other AEID of any other 498 block in the bundle sharing the same block type. 500 o The SSP offset of the AEID MUST be the value 0. There MUST NOT be 501 any other EID in the block header that has a value of 0 for the 502 SSP offset. 504 If there is no AEID present in a block, and if a node is unable to 505 add an AEID by following the above process, then the block MUST NOT 506 have an SBSP security operation applied to it. 508 It is RECOMMENDED that every block in a bundle other than the primary 509 and payload blocks be treated as a non-singleton block. However, the 510 identification of singleton blocks SHOULD be in accordance with the 511 security policy of a node. 513 3.2. Abstract Security Block 515 Each security block uses the Canonical Bundle Block Format as defined 516 in [RFC5050]. That is, each security block is comprised of the 517 following elements: 519 o Block Type Code 521 o Block Processing Control Flags 523 o Block EID Reference List (OPTIONAL) 525 o Block Data Length 527 o Block Type Specific Data Fields 529 Since the four security block types have most fields in common, we 530 can shorten the description of the block type specific data fields if 531 we first define an abstract security block (ASB) and then specify 532 each of the real blocks in terms of the fields that are present/ 533 absent in an ASB. Note that no bundle ever contains an actual ASB, 534 which is simply a specification artifact. 536 Internet-DrafStreamlined Bundle Security Protocol Specifica October 2015 538 The structure of an Abstract Security Block is given in Figure 2. 539 Although the diagram hints at a fixed-format layout, this is purely 540 for the purpose of exposition. Except for the "type" field, all 541 fields are variable in length. 543 +-----------------------------+----------------------------------+ 544 | Block Type Code (BYTE) | Processing Control Flags (SDNV) | 545 +-----------------------------+----------------------------------+ 546 | EID Reference Count and List (Compound List) | 547 +-----------------------------+----------------------------------+ 548 | Block Length (SDNV) | Security Target (Compound) | 549 +-----------------------------+----------------------------------+ 550 | Cipher suite ID (SDNV) | Cipher suite Flags (SDNV) | 551 +-----------------------------+----------------------------------+ 552 | Params Length (SDNV) | Params Data (Compound) | 553 +-----------------------------+----------------------------------+ 554 | Result Length (SDNV) | Result Data (Compound) | 555 +-----------------------------+----------------------------------+ 557 Figure 2: Abstract Security Block Structure 559 An ASB consists of the following fields, some of which are optional. 561 o Block-Type Code (Byte) - as described in [RFC5050]. The block- 562 type codes for security blocks are: 564 * BundleAuthenticationBlock - BAB: 0x02 566 * BlockIntegrityBlock - BIB: 0x03 568 * BlockConfidentialityBlock - BCB: 0x04 570 o Block Processing Control Flags (SDNV) - as described in [RFC5050]. 571 There are no general constraints on the use of the block 572 processing control flags, and some specific requirements are 573 discussed later. 575 o (OPTIONAL) EID Reference Count and List - as described in 576 [RFC5050]. Presence of the EID reference field is indicated by 577 the setting of the "Block contains an EID reference field" 578 (EID_REF) bit of the block processing control flags. If no EID 579 fields are present, then the composite field itself MUST be 580 omitted entirely and the EID_REF bit MUST be unset. A count field 581 of zero is not permitted. The possible EIDs are: 583 (OPTIONAL) Security-source - specifies the security-source for 584 the block. If this is omitted, then the source of the bundle 585 is assumed to be the security-source unless otherwise indicated 587 Internet-DrafStreamlined Bundle Security Protocol Specifica October 2015 589 by policy or associated cipher suite definition. When present, 590 the security-source MUST be the first EID in the list. 592 (OPTIONAL) AEID - specifies an identifier that can be used to 593 uniquely identify an instance of a non-singleton block. This 594 field MUST be present for non-singleton blocks. This field 595 MUST NOT be present for singleton blocks, such as the primary 596 block and the payload block. The construction of the AEID is 597 discussed in Section 3.1. 599 o Block Length (SDNV) - as described in [RFC5050]. 601 o Block type specific data fields as follows: 603 * Security-Target (Compound) - Uniquely identifies the target of 604 the associated security-operation. 606 As discussed in Section 3.1 a singleton block is identified by 607 its block type and a non-singleton block is identified by the 608 combination of its block type and an occurrence number. The 609 security-target is a compound field that contains the block 610 type (as a byte) and occurrence number (as an SDNV). 612 The occurrence number of a singleton block MUST be set to 0. 613 The occurrence number of a non-singleton block MUST be set to 614 the scheme offset of the AEID associated with the block being 615 targeted by the security operation. 617 * (OPTIONAL) Cipher suite ID (SDNV) 619 * (OPTIONAL) Cipher suite flags (SDNV) 621 * (OPTIONAL) Cipher Suite Parameters - compound field of the next 622 two items. 624 + Cipher suite parameters length (SDNV) - specifies the length 625 of the next field, which is the cipher suite-parameters data 626 field. 628 + Cipher suite parameters data - parameters to be used with 629 the cipher suite in use, e.g., a key identifier or 630 initialization vector (IV). See Section 3.9 for a list of 631 potential parameters and their encoding rules. The 632 particular set of parameters that is included in this field 633 is defined as part of a cipher suite specification. 635 * (OPTIONAL) Security Result - compound field of the next two 636 items. 638 Internet-DrafStreamlined Bundle Security Protocol Specifica October 2015 640 + Security result length (SDNV) - contains the length of the 641 next field, which is the security-result data field. 643 + Security result data - contains the results of the 644 appropriate cipher suite specific calculation (e.g., a 645 signature, Message Authentication Code (MAC), or cipher-text 646 block key). 648 The structure of the cipher suite flags field is shown in Figure 3. 649 In each case, the presence of an optional field is indicated by 650 setting the value of the corresponding flag to one. A value of zero 651 indicates the corresponding optional field is missing. Presently, 652 there are three flags defined for the field; for convenience, these 653 are shown as they would be extracted from a single-byte SDNV. Future 654 additions may cause the field to grow to the left so, as with the 655 flags fields defined in [RFC5050], the description below numbers the 656 bit positions from the right rather than the standard RFC definition, 657 which numbers bits from the left. 659 bits 6-3 are reserved for future use. 661 src - bit 2 indicates whether the EID-reference field of the ASB 662 contains the optional reference to the security-source. 664 parm - bit 1 indicates whether or not the cipher suite parameters 665 length and cipher suite parameters data fields are present. 667 res - bit 0 indicates whether or not the ASB contains the 668 security-result length and security-result data fields. 670 Bit Bit Bit Bit Bit Bit Bit 671 6 5 4 3 2 1 0 672 +-----+-----+-----+-----+-----+-----+-----+ 673 | reserved | src |parm | res | 674 +-----+-----+-----+-----+-----+-----+-----+ 676 Figure 3: Cipher Suite Flags 678 3.3. Block Ordering 680 A security-operation may be implemented in a bundle using either one 681 or two security blocks. For example, the operation 682 OP(authentication, bundle) MAY be accomplished by a single BAB block 683 in the bundle, or it MAY be accomplished by two BAB blocks in the 684 bundle. To avoid confusion, we use the following terminology to 685 identify the block or blocks comprising a security-operation. 687 Internet-DrafStreamlined Bundle Security Protocol Specifica October 2015 689 The terms "First" and "Last" are used ONLY when describing multiple 690 security blocks comprising a single security-operation. A "First" 691 block refers to the security block that is closest to the primary 692 block in the canonical form of the bundle. A "Last" block refers to 693 the security block that is furthest from the primary block in the 694 canonical form of the bundle. 696 If a single security block implements the security-operation, then it 697 is referred to as a "Lone" block. For example, when a bundle 698 authentication cipher suite requires a single BAB block we refer to 699 it as a Lone BAB. When a bundle authentication cipher suite requires 700 two BAB blocks we refer to them as the First BAB and the Last BAB. 702 This specification and individual cipher suites impose restrictions 703 on what optional fields must and must not appear in First blocks, 704 Last blocks, and Lone blocks. 706 3.4. Bundle Authentication Block 708 This section describes typical field values for the BAB, which is 709 solely used to implement OP(authentication, bundle). 711 The block-type code field value MUST be 0x02. 713 The block processing control flags value can be set to whatever 714 values are required by local policy. Cipher suite designers 715 should carefully consider the effect of setting flags that either 716 discard the block or delete the bundle in the event that this 717 block cannot be processed. 719 The security-target MUST be the entire bundle, which MUST be 720 represented by a of <0x00><0x00>. 722 The cipher suite ID MUST be documented as a hop-by-hop 723 authentication cipher suite. When a Lone BAB is used, the cipher 724 suite MUST be documented as requiring one instance of the BAB. 725 When a First BAB and Last BAB are used, the cipher suite MUST be 726 documented as requiring two instances of the BAB. 728 The cipher suite parameters field MAY be present, if so specified 729 in the cipher suite specification. 731 An EID-reference to the security-source MAY be present in either a 732 First BAB or a Lone BAB. An EID-reference to the security-source 733 MUST NOT be present in a Last BAB. 735 The security-result captures the result of applying the cipher 736 suite calculation (e.g., the MAC or signature) to the relevant 738 Internet-DrafStreamlined Bundle Security Protocol Specifica October 2015 740 parts of the bundle, as specified in the cipher suite definition. 741 This field MUST be present in either a Lone BAB or a Last BAB. 742 This field MUST NOT be present in a First BAB. 744 Notes: 746 o When multiple BAB blocks are used, the mandatory fields of the 747 Last BAB must match those of the First BAB. 749 o The First BAB or Lone BAB, when present, SHOULD immediately follow 750 the primary block. 752 o A Last BAB, when present, SHOULD be the last block in the bundle. 754 o Since OP(authentication, bundle) is allowed only once in a bundle, 755 it is RECOMMENDED that users wishing to support multiple 756 authentication signatures define a multi-target cipher suite, 757 capturing multiple security results in cipher suite parameters. 759 3.5. Block Integrity Block 761 A BIB is an ASB with the following additional restrictions: 763 The block-type code value MUST be 0x03. 765 The block processing control flags value can be set to whatever 766 values are required by local policy. Cipher suite designers 767 should carefully consider the effect of setting flags that either 768 discard the block or delete the bundle in the event that this 769 block cannot be processed. 771 The security-target MUST uniquely identify a block within the 772 bundle. The reserved block type 0x01 specifies the singleton 773 payload block. The reserved type 0x00 specifies the singleton 774 primary block. The security-target for a BIB MUST NOT reference a 775 security block defined in this specification (BAB, BIB, or BCB). 777 The cipher suite ID MUST be documented as an end-to-end 778 authentication-cipher suite or as an end-to-end error-detection- 779 cipher suite. 781 The cipher suite parameters field MAY be present in either a Lone 782 BIB or a First BIB. This field MUST NOT be present in a Last BIB. 784 An EID-reference to the security-source MAY be present in either a 785 Lone BIB or a First BIB. This field MUST NOT be present in a Last 786 BIB. 788 Internet-DrafStreamlined Bundle Security Protocol Specifica October 2015 790 The security-result captures the result of applying the cipher 791 suite calculation (e.g., the MAC or signature) to the relevant 792 parts of the security-target, as specified in the cipher suite 793 definition. This field MUST be present in either a Lone BIB or a 794 Last BIB. This field MUST NOT be present in a First BIB. 796 The cipher suite MAY process less than the entire security-target. 797 If the cipher suite processes less than the complete, original 798 security-target, the cipher suite parameters MUST specify which 799 bytes of the security-target are protected. 801 Notes: 803 o Since OP(integrity, target) is allowed only once in a bundle per 804 target, it is RECOMMENDED that users wishing to support multiple 805 integrity signatures for the same target define a multi-signature 806 cipher suite, capturing multiple security results in cipher suite 807 parameters. 809 o For some cipher suites, (e.g., those using asymmetric keying to 810 produce signatures or those using symmetric keying with a group 811 key), the security information MAY be checked at any hop on the 812 way to the destination that has access to the required keying 813 information, in accordance with Section 3.8. 815 o The use of a generally available key is RECOMMENDED if custodial 816 transfer is employed and all nodes SHOULD verify the bundle before 817 accepting custody. 819 3.6. Block Confidentiality Block 821 A BCB is an ASB with the following additional restrictions: 823 The block-type code value MUST be 0x04. 825 The block processing control flags value can be set to whatever 826 values are required by local policy, except that a Lone BCB or 827 First BCB MUST have the "replicate in every fragment" flag set. 828 This indicates to a receiving node that the payload portion in 829 each fragment represents cipher-tex 831 t. This flag SHOULD NOT be set otherwise. Cipher suite designers 832 should carefully consider the effect of setting flags that either 833 discard the block or delete the bundle in the event that this 834 block cannot be processed. 836 The security-target MUST uniquely identify a block within the 837 bundle. The security-target for a BCB MAY reference the payload 839 Internet-DrafStreamlined Bundle Security Protocol Specifica October 2015 841 block, a non-security extension block, or a BIB block. The 842 reserved type 0x01 specifies the singleton payload block. 844 The cipher suite ID MUST be documented as a confidentiality cipher 845 suite. 847 Key-information, if available, MUST appear only in a Lone BCB or a 848 First BCB. 850 Any additional bytes generated as a result of encryption and/or 851 authentication processing of the security-target SHOULD be placed 852 in an "integrity check value" field (see Section 3.9) in the 853 security-result of the Lone BCB or Last BCB. 855 The cipher suite parameters field MAY be present in either a Lone 856 BCB or a First BCB. This field MUST NOT be present in a Last BCB. 858 An EID-reference to the security-source MAY be present in either a 859 Lone BCB or a First BCB. This field MUST NOT be present in a Last 860 BCB. The security-source can also be specified as part of key- 861 information described in Section 3.9. 863 The security-result MAY be present in either a Lone BCB or a Last 864 BCB. This field MUST NOT be present in a First BCB. This 865 compound field normally contains fields such as an encrypted 866 bundle encryption key and/or authentication tag. 868 The BCB is the only security block that modifies the contents of its 869 security-target. When a BCB is applied, the security-target body 870 data are encrypted "in-place". Following encryption, the security- 871 target body data contains cipher-text, not plain-text. Other 872 security-target block fields (such as type, processing control flags, 873 and length) remain unmodified. 875 Fragmentation, reassembly, and custody transfer are adversely 876 affected by a change in size of the payload due to ambiguity about 877 what byte range of the block is actually in any particular fragment. 878 Therefore, when the security-target of a BCB is the bundle payload, 879 the BCB MUST NOT alter the size of the payload block body data. 880 Cipher suites SHOULD place any block expansion, such as 881 authentication tags (integrity check values) and any padding 882 generated by a block-mode cipher, into an integrity check value item 883 in the security-result field (see Section 3.9) of the BCB. This "in- 884 place" encryption allows fragmentation, reassembly, and custody 885 transfer to operate without knowledge of whether or not encryption 886 has occurred. 888 Notes: 890 Internet-DrafStreamlined Bundle Security Protocol Specifica October 2015 892 o The cipher suite MAY process less than the entire original 893 security-target body data. If the cipher suite processes less 894 than the complete, original security-target body data, the BCB for 895 that security-target MUST specify, as part of the cipher suite 896 parameters, which bytes of the body data are protected. 898 o The BCB's "discard" flag may be set independently from its 899 security-target's "discard" flag. Whether or not the BCB's 900 "discard" flag is set is an implementation/policy decision for the 901 encrypting node. (The "discard" flag is more properly called the 902 "Discard if block cannot be processed" flag.) 904 o A BCB MAY include information as part of additional authenticated 905 data to address parts of the target block, such as EID references, 906 that are not converted to cipher-text. 908 3.7. Cryptographic Message Syntax Block 910 A CMSB is an ASB with the following additional restrictions: 912 The block-type code value MUST be 0x05. 914 The content of the block must contain valid CMS data, as defined 915 in RFC 5652, and encoded in X.690 BER or DER encoding. 917 The block processing control flags value can be set to whatever 918 values are required by local policy. This flag SHOULD NOT be set 919 otherwise. Cipher suite designers should carefully consider the 920 effect of setting flags that either discard the block or delete 921 the bundle in the event that this block cannot be processed. 923 The security-target MUST uniquely identify a block within the 924 bundle. The reserved block type 0x01 specifies the singleton 925 payload block. 927 The security operation(s) will be performed on the security-target 928 block's data and the resulting CMS content will be stored within 929 the CMSB block's security-result field. The security-target 930 block's data will then be removed. 932 A CMSB block MAY include multiple CMS security operations within a 933 single block to allow for multiple nested operations to be 934 performed on a bundle block. Multiple CMSB blocks MAY be included 935 in a bundle as long as the security-target for each is unique. 937 Key-information, if available, MUST appear within the CMS content 938 contained in the security-result field. 940 Internet-DrafStreamlined Bundle Security Protocol Specifica October 2015 942 A CMSB block is created with its corresponding security-target field 943 pointing to a unique bundle block. The CMS security operations are 944 performed upon the security-target's data field and the resulting 945 encoded CMS content is stored within the CMS security-result field of 946 the CMSB's payload. The security-target block's data MAY be left 947 intact, replaced with alternate data, or completely erased based on 948 the specification of the utilized CMS ciphersuite definition and 949 applicable policy. 951 Multiple CMS operations may be nested within a single CMSB block to 952 allow more than one security operation to be performed upon a 953 security-target. 955 CMS Operations can be considered to have SBSP parallels: CMSB 956 Enveloped-Data content type SHALL be considered as equivalent to a 957 SBSP BCB block, and a CMSB Signed-Data type SHALL be considered as 958 equivalent to a SBSP BIB block. 960 3.8. Block Interactions 962 The four security-block types defined in this specification are 963 designed to be as independent as possible. However, there are some 964 cases where security blocks may share a security-target creating 965 processing dependencies. 967 If confidentiality is being applied to a target that already has 968 integrity applied to it, then an undesirable condition occurs where a 969 security-aware intermediate node would be unable to check the 970 integrity result of a block because the block contents have been 971 encrypted after the integrity signature was generated. To address 972 this concern, the following processing rules MUST be followed. 974 o If confidentiality is to be applied to a target, it MUST also be 975 applied to every integrity operation already defined for that 976 target. This means that if a BCB is added to encrypt a block, 977 another BCB MUST also be added to encrypt a BIB also targeting 978 that block. 980 o An integrity operation MUST NOT be applied to a security-target if 981 a BCB in the bundle shares the same security-target. This 982 prevents ambiguity in the order of evaluation when receiving a BIB 983 and a BCB for a given security-target. 985 o An integrity value MUST NOT be evaluated if the BIB providing the 986 integrity value is the security target of an existing BCB block in 987 the bundle. In such a case, the BIB data contains cipher-text as 988 it has been encrypted. 990 Internet-DrafStreamlined Bundle Security Protocol Specifica October 2015 992 o An integrity value MUST NOT be evaluated if the security-target of 993 the BIB is also the security-target of a BCB in the bundle. In 994 such a case, the security-target data contains cipher-text as it 995 has been encrypted. 997 o As mentioned in Section 3.6, a BIB MUST NOT have a BCB as its 998 security target. BCBs may embed integrity results as part of 999 cipher suite parameters. 1001 o As mentioned in Section 4.4, CMS operations are considered to have 1002 operational parallels. When a CMSB is used, these parallels MUST 1003 be considered for block interactions (e.g., a Signed-Data 1004 structure MUST NOT be evaluated if the security-target of the 1005 operation is also the security-target of a BCB) 1007 o If a single bundle is going to contain a CMSB as well as other 1008 security blocks, the CMS operations MUST be performed and the CMSB 1009 MUST be created before any other security operation is applied. 1011 o On reception of a bundle containing a CMSB and other security 1012 blocks, the CMSB must be decoded last. 1014 Additionally, since the CMSB block may contain either integrity or 1015 confidentiality information in its encapsulated CMS, there is no way 1016 to evaluate conflicts when a BIB/BCB and a CMSB have the same 1017 security target. To address this concern, the following processing 1018 rules MUST be followed. 1020 o If an extension block is the target of a BIB or a BCB, then the 1021 extension block MUST NOT also be the target of a CMSB, and vice- 1022 versa. 1024 o If a bundle is the target of a BAB block, then the bundle MUST NOT 1025 also be the target of a CMSB, and vice-versa. 1027 o Generally, a CMSB MUST be processed before any BIB or BCB blocks 1028 are processed. 1030 These restrictions on block interactions impose a necessary ordering 1031 when applying security operations within a bundle. Specifically, for 1032 a given security-target, BIBs MUST be added before BCBs, and BABs 1033 MUST be added after all other security blocks. This ordering MUST be 1034 preserved in cases where the current BPA is adding all of the 1035 security blocks for the bundle or whether the BPA is a waypoint 1036 adding new security blocks to a bundle that already contains security 1037 blocks. 1039 Internet-DrafStreamlined Bundle Security Protocol Specifica October 2015 1041 3.9. Parameters and Result Fields 1043 Various cipher suites include several items in the cipher suite 1044 parameters and/or security-result fields. Which items MAY appear is 1045 defined by the particular cipher suite description. A cipher suite 1046 MAY support several instances of the same type within a single block. 1048 Each item is represented as a type-length-value. Type is a single 1049 byte indicating the item. Length is the count of data bytes to 1050 follow, and is an SDNV-encoded integer. Value is the data content of 1051 the item. 1053 Item types, name, and descriptions are defined as follows. 1055 Internet-DrafStreamlined Bundle Security Protocol Specifica October 2015 1057 Cipher suite parameters and result fields. 1059 +-------+----------------+------------------------------------------+ 1060 | Type | Name | Description | 1061 +-------+----------------+------------------------------------------+ 1062 | 0 | Reserved | | 1063 +-------+----------------+------------------------------------------+ 1064 | 1 | Initialization | A random value, typically eight to | 1065 | | Vector (IV) | sixteen bytes. | 1066 +-------+----------------+------------------------------------------+ 1067 | 2 | Reserved | | 1068 +-------+----------------+------------------------------------------+ 1069 | 3 | Key | Material encoded or protected by the key | 1070 | | Information | management system and used to transport | 1071 | | | an ephemeral key protected by a long- | 1072 | | | term key. | 1073 +-------+----------------+------------------------------------------+ 1074 | 4 | Content Range | Pair of SDNV values (offset,length) | 1075 | | | specifying the range of payload bytes to | 1076 | | | which an operation applies. The offset | 1077 | | | MUST be the offset within the original | 1078 | | | bundle, even if the current bundle is a | 1079 | | | fragment. | 1080 +-------+----------------+------------------------------------------+ 1081 | 5 | Integrity | Result of BAB or BIB digest or other | 1082 | | Signatures | signing operation. | 1083 +-------+----------------+------------------------------------------+ 1084 | 6 | Unassigned | | 1085 +-------+----------------+------------------------------------------+ 1086 | 7 | Salt | An IV-like value used by certain | 1087 | | | confidentiality suites. | 1088 +-------+----------------+------------------------------------------+ 1089 | 8 | BCB Integrity | Output from certain confidentiality | 1090 | | Check Value | cipher suite operations to be used at | 1091 | | (ICV) / | the destination to verify that the | 1092 | | Authentication | protected data has not been modified. | 1093 | | Tag | This value MAY contain padding if | 1094 | | | required by the cipher suite. | 1095 +-------+----------------+------------------------------------------+ 1096 | 9-255 | Reserved | | 1097 +-------+----------------+------------------------------------------+ 1099 Table 1 1101 Internet-DrafStreamlined Bundle Security Protocol Specifica October 2015 1103 3.10. BSP Block Example 1105 An example of SBSP blocks applied to a bundle is illustrated in 1106 Figure 4. In this figure the first column represents blocks within a 1107 bundle and the second column represents a unique identifier for each 1108 block, suitable for use as the security-target of a SBSP security- 1109 block. Since the mechanism and format of a security-target is not 1110 specified in this document, the terminology B1...Bn is used to 1111 identify blocks in the bundle for the purposes of illustration. 1113 Block in Bundle ID 1114 +=================================+====+ 1115 | Primary Block | B1 | 1116 +---------------------------------+----+ 1117 | First BAB | B2 | 1118 | OP(authentication, Bundle) | | 1119 +---------------------------------+----+ 1120 | Lone BIB | B3 | 1121 | OP(integrity, target=B1) | | 1122 +---------------------------------+----+ 1123 | Lone BCB | B4 | 1124 | OP(confidentiality, target=B5) | | 1125 +---------------------------------+----+ 1126 | Extension Block | B5 | 1127 +---------------------------------+----+ 1128 | Lone BIB | B6 | 1129 | OP(integrity, target=B7) | | 1130 +---------------------------------+----+ 1131 | Extension Block | B7 | 1132 +---------------------------------+----+ 1133 | Lone BCB | B8 | 1134 | OP(confidentiality, target=B9) | | 1135 +---------------------------------+----+ 1136 | Lone BIB (encrypted by B8) | B9 | 1137 | OP(integrity, target=B11) | | 1138 +---------------------------------+----+ 1139 | Lone BCB |B10 | 1140 | OP(confidentiality, target=B11) | | 1141 +---------------------------------+----+ 1142 | Payload Block |B11 | 1143 +---------------------------------+----+ 1144 | Last BAB |B12 | 1145 | OP(authentication, Bundle) | | 1146 +---------------------------------+----+ 1148 Figure 4: Sample Use of BSP Blocks 1150 Internet-DrafStreamlined Bundle Security Protocol Specifica October 2015 1152 In this example a bundle has four non-security-related blocks: the 1153 primary block (B1), two extension blocks (B5,B7), and a payload block 1154 (B11). The following security applications are applied to this 1155 bundle. 1157 o Authentication over the bundle. This is accomplished by two BAB 1158 blocks: B2 and B12. 1160 o An integrity signature applied to the canonicalized primary block. 1161 This is accomplished by a single BIB, B3. 1163 o Confidentiality for the first extension block. This is 1164 accomplished by a single BCB block, B4. 1166 o Integrity for the second extension block. This is accomplished by 1167 a single BIB block, B6. 1169 o An integrity signature on the payload. This is accomplished by a 1170 single BIB block, B9. 1172 o Confidentiality for the payload block and it's integrity 1173 signature. This is accomplished by two Lone BCB blocks: B8 1174 encrypting B9, and B10 encrypting B11. 1176 Internet-DrafStreamlined Bundle Security Protocol Specifica October 2015 1178 Block in Bundle ID 1179 +=========================================+====+ 1180 | Primary Block | B1 | 1181 +-----------------------------------------+----+ 1182 | First BAB | B2 | 1183 | OP(authentication, Bundle) | | 1184 +-----------------------------------------+----+ 1185 | Lone CMSB | B3 | 1186 | security-target=0x01 | | 1187 | security-result= | | 1188 | | | 1189 | Signed-Data { | | 1190 | Digest Algorithm(s), | | 1191 | Enveloped-Data { | | 1192 | Encrypted Data, | | 1193 | Encrypted Encryption Key(s) | | 1194 | }, | | 1195 | Signature(s) and Certificate Chain(s) | | 1196 | } | | 1197 | | | 1198 +-----------------------------------------+----+ 1199 | Payload Block | B4 | 1200 | (Empty Data Field) | | 1201 +-----------------------------------------+----+ 1202 | Last BAB | B5 | 1203 | OP(authentication, Bundle) | | 1204 +-----------------------------------------+----+ 1206 Figure 5: Sample Bundle With CMS Block 1208 In this example a bundle has two non-security-related blocks: the 1209 primary block (B1) and a payload block (B4). This method would allow 1210 for the bundle to carry multiple CMS payloads by utilizing a multiple 1211 CMSB ASBs. The following security applications are applied to this 1212 bundle. 1214 o Authentication over the bundle. This is accomplished by two BAB 1215 blocks: B2 and B5. 1217 o Encrypted and signed CMS content contained within the CMSB block. 1218 The first CMS operation, encryption, is performed on the data 1219 contained within the block the security-target points to, in this 1220 case, the payload block. The resulting encrypted data is then 1221 signed and the final CMS content is stored within the CMSB block's 1222 security-result field. The payload block's data is subsequently 1223 removed now that the original data has been encoded within the 1224 CMSB block. 1226 Internet-DrafStreamlined Bundle Security Protocol Specifica October 2015 1228 4. Security Processing 1230 This section describes the security aspects of bundle processing. 1232 4.1. Canonical Forms 1234 In order to verify a signature of a bundle, the exact same bits, in 1235 the exact same order, MUST be input to the calculation upon 1236 verification as were input upon initial computation of the original 1237 signature value. Consequently, a node MUST NOT change the encoding 1238 of any URI [RFC3986] in the dictionary field, e.g., changing the DNS 1239 part of some HTTP URL from lower case to upper case. Because bundles 1240 MAY be modified while in transit (either correctly or due to 1241 implementation errors), canonical forms of security-targets MUST be 1242 defined. 1244 Many fields in various blocks are stored as variable-length SDNVs. 1245 These are canonicalized into an "unpacked form" as eight-byte fixed- 1246 width fields in network byte order. The size of eight bytes is 1247 chosen because implementations MAY handle larger SDNV values as 1248 invalid, as noted in [RFC5050]. 1250 4.1.1. Bundle Canonicalization 1252 Bundle canonicalization permits no changes at all to the bundle 1253 between the security-source and the destination, with the exception 1254 of one of the Block Processing Control Flags, as described below. It 1255 is intended for use in BAB cipher suites. This algorithm 1256 conceptually catenates all blocks in the order presented, but omits 1257 all security-result data fields in security blocks having the bundle 1258 as their security-target. For example, when a BAB cipher suite 1259 specifies this algorithm, we omit the BAB security-result from the 1260 catenation. The inclusion of security-result length fields is as 1261 determined by the specified cipher suite. A security-result length 1262 field MAY be present even when the corresponding security-result data 1263 fields are omitted. 1265 Notes: 1267 o In the Block Processing Control Flags field the unpacked SDNV is 1268 ANDed with mask 0xFFFF FFFF FFFF FFDF to zero the flag at bit 5 1269 ("Block was forwarded without being processed"). If this flag is 1270 not zeroed out, then a bundle passing through a non-security aware 1271 node will set this flag which will change the message digest and 1272 the BAB block will fail to verify. 1274 o In the above, we specify that security-result data is omitted. 1275 This means that no bytes of the security-result data are input. 1277 Internet-DrafStreamlined Bundle Security Protocol Specifica October 2015 1279 If the security-result length is included in the catenation, we 1280 assume that the security-result length will be known to the module 1281 that implements the cipher suite before the security-result is 1282 calculated, and require that this value be in the security-result 1283 length field even though the security-result data itself will be 1284 omitted. 1286 o The 'res' bit of the cipher suite ID, which indicates whether or 1287 not the security-result length and security-result data field are 1288 present, is part of the canonical form. 1290 o The value of the block data length field, which indicates the 1291 length of the block, is also part of the canonical form. Its 1292 value indicates the length of the entire block when the block 1293 includes the security-result data field. 1295 4.1.2. Block Canonicalization 1297 This algorithm protects those parts of a block that SHOULD NOT be 1298 changed in transit. 1300 There are three types of blocks that may undergo block 1301 canonicalization: the primary block, the payload block, or an 1302 extension block. 1304 4.1.2.1. Primary Block Canonicalization 1306 The canonical form of the primary block is shown in Figure 6. 1307 Essentially, it de-references the dictionary block, adjusts lengths 1308 where necessary, and ignores flags that may change in transit. 1310 Internet-DrafStreamlined Bundle Security Protocol Specifica October 2015 1312 +----------------+----------------+----------------+----------------+ 1313 | Version | Processing flags (incl. COS and SRR) | 1314 +----------------+----------------+---------------------------------+ 1315 | Canonical primary block length | 1316 +----------------+----------------+---------------------------------+ 1317 | Destination endpoint ID length | 1318 +----------------+----------------+---------------------------------+ 1319 | Destination endpoint ID | 1320 +----------------+----------------+---------------------------------+ 1321 | Source endpoint ID length | 1322 +----------------+----------------+----------------+----------------+ 1323 | Source endpoint ID | 1324 +----------------+----------------+---------------------------------+ 1325 | Report-to endpoint ID length | 1326 +----------------+----------------+----------------+----------------+ 1327 | Report-to endpoint ID | 1328 +----------------+----------------+----------------+----------------+ 1329 + Creation Timestamp (2 x SDNV) + 1330 +---------------------------------+---------------------------------+ 1331 | Lifetime | 1332 +----------------+----------------+----------------+----------------+ 1334 Figure 6: The Canonical Form of the Primary Bundle Block 1336 The fields shown in Figure 6 are as follows: 1338 o The version value is the single-byte value in the primary block. 1340 o The processing flags value in the primary block is an SDNV, and 1341 includes the class-of-service (COS) and status report request 1342 (SRR) fields. For purposes of canonicalization, the unpacked SDNV 1343 is ANDed with mask 0x0000 0000 0007 C1BE to set to zero all 1344 reserved bits and the "bundle is a fragment" bit. 1346 o The canonical primary block length value is a four-byte value 1347 containing the length (in bytes) of this structure, in network 1348 byte order. 1350 o The destination endpoint ID length and value are the length (as a 1351 four-byte value in network byte order) and value of the 1352 destination endpoint ID from the primary bundle block. The URI is 1353 simply copied from the relevant part(s) of the dictionary block 1354 and is not itself canonicalized. Although the dictionary entries 1355 contain "null-terminators", the null-terminators are not included 1356 in the length or the canonicalization. 1358 o The source endpoint ID length and value are handled similarly to 1359 the destination. 1361 Internet-DrafStreamlined Bundle Security Protocol Specifica October 2015 1363 o The report-to endpoint ID length and value are handled similarly 1364 to the destination. 1366 o The unpacked SDNVs for the creation timestamp and lifetime are 1367 copied from the primary block. 1369 o Fragment offset and total application data unit length are 1370 ignored, as is the case for the "bundle is a fragment" bit 1371 mentioned above. If the payload data to be canonicalized is less 1372 than the complete, original bundle payload, the offset and length 1373 are specified in the cipher suite parameters. 1375 4.1.2.2. Payload Block Canonicalization 1377 When canonicalizing the payload block, the block processing control 1378 flags value used for canonicalization is the unpacked SDNV value with 1379 reserved and mutable bits masked to zero. The unpacked value is 1380 ANDed with mask 0x0000 0000 0000 0077 to zero reserved bits and the 1381 "last block" bit. The "last block" bit is ignored because BABs and 1382 other security blocks MAY be added for some parts of the journey but 1383 not others, so the setting of this bit might change from hop to hop. 1385 Payload blocks are canonicalized as-is, with the exception that, in 1386 some instances, only a portion of the payload data is to be 1387 protected. In such a case, only those bytes are included in the 1388 canonical form, and additional cipher suite parameters are required 1389 to specify which part of the payload is protected, as discussed 1390 further below. 1392 4.1.2.3. Extension Block Canonicalization 1394 When canonicalizing an extension block, the block processing control 1395 flags value used for canonicalization is the unpacked SDNV value with 1396 reserved and mutable bits masked to zero. The unpacked value is 1397 ANDed with mask 0x0000 0000 0000 0057 to zero reserved bits, the 1398 "last block" flag and the "Block was forwarded without being 1399 processed" bit. The "last block" flag is ignored because BABs and 1400 other security blocks MAY be added for some parts of the journey but 1401 not others, so the setting of this bit might change from hop to hop. 1403 The "Block was forwarded without being processed" flag is ignored 1404 because the bundle may pass through nodes that do not understand that 1405 extension block and this flag would be set. 1407 Endpoint ID references in blocks are canonicalized using the de- 1408 referenced text form in place of the reference pair. The reference 1409 count is not included, nor is the length of the endpoint ID text. 1411 Internet-DrafStreamlined Bundle Security Protocol Specifica October 2015 1413 The EID reference is, therefore, canonicalized as :, 1414 which includes the ":" character. 1416 Since neither the length of the canonicalized EID text nor a null- 1417 terminator is used in EID canonicalization, a separator token MUST be 1418 used to determine when one EID ends and another begins. When 1419 multiple EIDs are canonicalized together, the character "," SHALL be 1420 placed between adjacent instances of EID text. 1422 The block-length is canonicalized as its unpacked SDNV value. If the 1423 data to be canonicalized is less than the complete, original block 1424 data, this field contains the size of the data being canonicalized 1425 (the "effective block") rather than the actual size of the block. 1427 4.1.3. Considerations 1429 o The canonical forms for the bundle and various extension blocks is 1430 not transmitted. It is simply an artifact used as input to 1431 digesting. 1433 o We omit the reserved flags because we cannot determine if they 1434 will change in transit. The masks specified above will have to be 1435 revised if additional flags are defined and they need to be 1436 protected. 1438 o Our URI encoding does not preserve the null-termination convention 1439 from the dictionary field, nor do we canonicalize the scheme and 1440 scheme-specific part (SSP) separately. Instead, the byte array < 1441 scheme name > : < scheme-specific part (SSP)> is used in the 1442 canonicalization. 1444 o The URI encoding will cause errors if any node rewrites the 1445 dictionary content (e.g., changing the DNS part of an HTTP URL 1446 from lower case to upper case). This could happen transparently 1447 when a bundle is synched to disk using one set of software and 1448 then read from disk and forwarded by a second set of software. 1449 Because there are no general rules for canonicalizing URIs (or 1450 IRIs), this problem may be an unavoidable source of integrity 1451 failures. 1453 o All SDNV fields here are canonicalized as eight-byte unpacked 1454 values in network byte order. Length fields are canonicalized as 1455 four-byte values in network byte order. Encoding does not need 1456 optimization since the values are never sent over the network. 1458 o These canonicalization algorithms assume that endpoint IDs 1459 themselves are immutable and they are unsuitable for use in 1460 environments where that assumption might be violated. 1462 Internet-DrafStreamlined Bundle Security Protocol Specifica October 2015 1464 o Cipher suites MAY define their own canonicalization algorithms and 1465 require the use of those algorithms over the ones provided in this 1466 specification. 1468 4.2. Endpoint ID Confidentiality 1470 Every bundle has a primary block that contains the source and 1471 destination endpoint IDs, and possibly other EIDs (in the dictionary 1472 field) that cannot be encrypted. If endpoint ID confidentiality is 1473 required, then bundle-in-bundle encapsulation can solve this problem 1474 in some instances. 1476 Similarly, confidentiality requirements MAY also apply to other parts 1477 of the primary block (e.g., the current-custodian), and that is 1478 supported in the same manner. 1480 4.3. Bundles Received from Other Nodes 1482 Security blocks MUST be processed in a specific order when received 1483 by a security-aware node. The processing order is as follows. 1485 o All BAB blocks in the bundle MUST be evaluated prior to evaluating 1486 any other block in the bundle. 1488 o All BCB blocks in the bundle MUST be evaluated prior to evaluating 1489 any BIBs in the bundle. When BIBs and BCBs share a security- 1490 target, BCBs MUST be evaluated first and BIBs second. 1492 4.3.1. Receiving BAB Blocks 1494 Nodes implementing this specification SHALL consult their security 1495 policy to determine whether or not a received bundle is required by 1496 policy to include a BAB. 1498 If the bundle is not required to have a BAB then BAB processing on 1499 the received bundle is complete, and the bundle is ready to be 1500 further processed for BIB/BCB handling or delivery or forwarding. 1501 Security policy may provide a means to override this default behavior 1502 and require processing of a BAB if it exists. 1504 If the bundle is required to have a BAB but does not, then the bundle 1505 MUST be discarded and processed no further. If the bundle is 1506 required to have a BAB but the key information for the security- 1507 source cannot be determined or the security-result value check fails, 1508 then the bundle has failed to authenticate, and the bundle MUST be 1509 discarded and processed no further. 1511 Internet-DrafStreamlined Bundle Security Protocol Specifica October 2015 1513 If the bundle is required to have a BAB, and a BAB exists, and the 1514 BAB information is verified, then the BAB processing on the received 1515 bundle is complete, and the bundle is ready to be further processed 1516 for BIB/BCB handling or delivery or forwarding. 1518 A BAB received in a bundle MUST be stripped before the bundle is 1519 forwarded. A new BAB MAY be added as required by policy. This MAY 1520 require correcting the "last block" field of the to-be-forwarded 1521 bundle. 1523 4.3.2. Receiving BCB Blocks 1525 If the bundle has a BCB and the receiving node is the destination for 1526 the bundle, the node MUST decrypt the relevant parts of the security- 1527 target in accordance with the cipher suite specification. 1529 If the relevant parts of an encrypted payload cannot be decrypted 1530 (i.e., the decryption key cannot be deduced or decryption fails), 1531 then the bundle MUST be discarded and processed no further; in this 1532 case, a bundle deletion status report (see [RFC5050]) indicating the 1533 decryption failure MAY be generated. If any other encrypted 1534 security-target cannot be decrypted then the associated security- 1535 target and all security blocks associated with that target MUST be 1536 discarded and processed no further. 1538 When a BCB is decrypted, the recovered plain-text MUST replace the 1539 cipher-text in the security-target body data 1541 4.3.3. Receiving BIB Blocks 1543 A BIB MUST NOT be processed if the security-target of the BIB is also 1544 the security-target of a BCB in the bundle. Given the order of 1545 operations mandated by this specification, when both a BIB and a BCB 1546 share a security-target, it means that the security-target MUST have 1547 been encrypted after it was integrity signed and, therefore, the BIB 1548 cannot be verified until the security-target has been decrypted by 1549 processing the BCB. 1551 If the security policy of a security-aware node specifies that a 1552 bundle SHOULD apply integrity to a specific security-target and no 1553 such BIB is present in the bundle, then the node MUST process this 1554 security-target in accordance with the security policy. This MAY 1555 involve removing the security-target from the bundle. If the removed 1556 security-target is the payload or primary block, the bundle MAY be 1557 discarded. This action may occur at any node that has the ability to 1558 verify an integrity signature, not just the bundle destination. 1560 Internet-DrafStreamlined Bundle Security Protocol Specifica October 2015 1562 If the bundle has a BIB and the receiving node is the destination for 1563 the bundle, the node MUST verify the security-target in accordance 1564 with the cipher suite specification. If a BIB check fails, the 1565 security-target has failed to authenticate and the security-target 1566 SHALL be processed according to the security policy. A bundle status 1567 report indicating the failure MAY be generated. Otherwise, if the 1568 BIB verifies, the security-target is ready to be processed for 1569 delivery. 1571 If the bundle has a BIB and the receiving node is not the bundle 1572 destination, the receiving node MAY attempt to verify the value in 1573 the security-result field. If the check fails, the node SHALL 1574 process the security-target in accordance to local security policy. 1575 It is RECOMMENDED that if a payload integrity check fails at a 1576 waypoint that it is processed in the same way as if the check fails 1577 at the destination. 1579 4.4. Receiving CMSB Blocks 1581 A CMSB MUST NOT be processed if its security target is also the 1582 security target of any BAB, BIB, or BCB in the bundle. 1584 The security services provided by a CMSB will be considered 1585 successful if all services in the CMSB are validated. If any one 1586 service encapsulated in the CMSB fails to validate, then the CMSB 1587 MUST be considered as having failed to validate and MUST be 1588 dispositioned in accordance with security policy. 1590 4.5. Bundle Fragmentation and Reassembly 1592 If it is necessary for a node to fragment a bundle and security 1593 services have been applied to that bundle, the fragmentation rules 1594 described in [RFC5050] MUST be followed. As defined there and 1595 repeated here for completeness, only the payload may be fragmented; 1596 security blocks, like all extension blocks, can never be fragmented. 1597 In addition, the following security-specific processing is REQUIRED: 1599 o Due to the complexity of bundle fragmentation, including the 1600 possibility of fragmenting bundle fragments, integrity and 1601 confidentiality operations are not to be applied to a bundle 1602 fragment. Specifically, a BCB or BIB MUST NOT be added to a 1603 bundle fragment, even if the security-target of the security block 1604 is not the payload. When integrity and confidentiality must be 1605 applied to a fragment, we RECOMMEND that encapsulation be used 1606 instead. 1608 Internet-DrafStreamlined Bundle Security Protocol Specifica October 2015 1610 o The authentication security policy requirements for a bundle MUST 1611 be applied individually to all the bundles resulting from a 1612 fragmentation event. 1614 o A BAB cipher suite MAY specify that it only applies to non- 1615 fragmented bundles and not to bundle fragments. 1617 o The decision to fragment a bundle MUST be made prior to adding 1618 authentication to the bundle. The bundle MUST first be fragmented 1619 and authentication applied to each individual fragment. 1621 o If a bundle with a BAB is fragmented by a non-security-aware node, 1622 then the entire bundle must be re-assembled before being processed 1623 to allow for the proper verification of the BAB. 1625 4.6. Reactive Fragmentation 1627 When a partial bundle has been received, the receiving node SHALL 1628 consult its security policy to determine if it MAY fragment the 1629 bundle, converting the received portion into a bundle fragment for 1630 further forwarding. Whether or not reactive fragmentation is 1631 permitted SHALL depend on the security policy and the cipher suite 1632 used to calculate the BAB authentication information, if required. 1634 Specifically, if the security policy does not require authentication, 1635 then reactive fragmentation MAY be permitted. If the security policy 1636 does require authentication, then reactive fragmentation MUST NOT be 1637 permitted if the partial bundle is not sufficient to allow 1638 authentication. 1640 If reactive fragmentation is allowed, then all BAB blocks must be 1641 removed from created fragments. 1643 5. Key Management 1645 Key management in delay-tolerant networks is recognized as a 1646 difficult topic and is one that this specification does not attempt 1647 to solve. 1649 6. Policy Considerations 1651 When implementing the SBSP, several policy decisions must be 1652 considered. This section describes key policies that affect the 1653 generation, forwarding, and receipt of bundles that are secured using 1654 this specification. 1656 o If a bundle is received that contains more than one security- 1657 operation, in violation of the SBSP, then the BPA must determine 1659 Internet-DrafStreamlined Bundle Security Protocol Specifica October 2015 1661 how to handle this bundle. The bundle may be discarded, the block 1662 affected by the security-operation may be discarded, or one 1663 security-operation may be favored over another. 1665 o BPAs in the network MUST understand what security-operations they 1666 should apply to bundles. This decision may be based on the source 1667 of the bundle, the destination of the bundle, or some other 1668 information related to the bundle. 1670 o If an intermediate receiver has been configured to add a security- 1671 operation to a bundle, and the received bundle already has the 1672 security-operation applied, then the receiver MUST understand what 1673 to do. The receiver may discard the bundle, discard the security- 1674 target and associated SBSP blocks, replace the security-operation, 1675 or some other action. 1677 o It is recommended that security operations only be applied to the 1678 payload block, the primary block, and any block-types specifically 1679 identified in the security policy. If a BPA were to apply 1680 security operations such as integrity or confidentiality to every 1681 block in the bundle, regardless of the block type, there could be 1682 downstream errors processing blocks whose contents must be 1683 inspected at every hop in the network path. 1685 7. Security Considerations 1687 Certain applications of DTN need to both sign and encrypt a message, 1688 and there are security issues to consider with this. 1690 o To provide an assurance that a security-target came from a 1691 specific source and has not been changed, then it should be signed 1692 with a BIB. 1694 o To ensure that a security-target cannot be inspected during 1695 transit, it should be encrypted with a BCB. 1697 o Adding a BIB to a security-target that has already been encrypted 1698 by a BCB is not allowed. Therefore, we recommend three methods to 1699 add an integrity signature to an encrypted security-target. 1700 First, at the time of encryption, an integrity signature may be 1701 generated and added to the BCB for the security-target as 1702 additional information in the security-result field. Second, the 1703 encrypted block may be replicated as a new block and integrity 1704 signed. Third, an encapsulation scheme may be applied to 1705 encapsulate the security-target (or the entire bundle) such that 1706 the encapsulating structure is, itself, no longer the security- 1707 target of a BCB and may therefore be the security-target of a BIB. 1709 Internet-DrafStreamlined Bundle Security Protocol Specifica October 2015 1711 8. Conformance 1713 All implementations are strongly RECOMMENDED to provide at least a 1714 BAB cipher suite. A relay node, for example, might not deal with 1715 end-to-end confidentiality and data integrity, but it SHOULD exclude 1716 unauthorized traffic and perform hop-by-hop bundle verification. 1718 9. IANA Considerations 1720 This protocol has fields that have been registered by IANA. 1722 9.1. Bundle Block Types 1724 This specification allocates three block types from the existing 1725 "Bundle Block Types" registry defined in [RFC6255]. 1727 Additional Entries for the Bundle Block-Type Codes Registry: 1729 +-------+-----------------------------+---------------+ 1730 | Value | Description | Reference | 1731 +-------+-----------------------------+---------------+ 1732 | 2 | Bundle Authentication Block | This document | 1733 | 3 | Block Integrity Block | This document | 1734 | 4 | Block Confidentiality Block | This document | 1735 +-------+-----------------------------+---------------+ 1737 Table 2 1739 9.2. Cipher Suite Flags 1741 This protocol has a cipher suite flags field and certain flags are 1742 defined. An IANA registry has been set up as follows. 1744 The registration policy for this registry is: Specification Required 1746 The Value range is: Variable Length 1748 Internet-DrafStreamlined Bundle Security Protocol Specifica October 2015 1750 Cipher Suite Flag Registry: 1752 +--------------------------+-------------------------+--------------+ 1753 | Bit Position (right to | Description | Reference | 1754 | left) | | | 1755 +--------------------------+-------------------------+--------------+ 1756 | 0 | Block contains result | This | 1757 | | | document | 1758 | 1 | Block Contains | This | 1759 | | parameters | document | 1760 | 2 | Source EID ref present | This | 1761 | | | document | 1762 | >3 | Reserved | This | 1763 | | | document | 1764 +--------------------------+-------------------------+--------------+ 1766 Table 3 1768 9.3. Parameters and Results 1770 This protocol has fields for cipher suite parameters and results. 1771 The field is a type-length-value triple and a registry is required 1772 for the "type" sub-field. The values for "type" apply to both the 1773 cipher suite parameters and the cipher suite results fields. Certain 1774 values are defined. An IANA registry has been set up as follows. 1776 The registration policy for this registry is: Specification Required 1778 The Value range is: 8-bit unsigned integer. 1780 Internet-DrafStreamlined Bundle Security Protocol Specifica October 2015 1782 Cipher Suite Parameters and Results Type Registry: 1784 +---------+---------------------------------+---------------+ 1785 | Value | Description | Reference | 1786 +---------+---------------------------------+---------------+ 1787 | 0 | reserved | This document | 1788 | 1 | initialization vector (IV) | This document | 1789 | 2 | reserved | This document | 1790 | 3 | key-information | This document | 1791 | 4 | content-range (pair of SDNVs) | This document | 1792 | 5 | integrity signature | This document | 1793 | 6 | unassigned | This document | 1794 | 7 | salt | This document | 1795 | 8 | BCB integrity check value (ICV) | This document | 1796 | 9-191 | reserved | This document | 1797 | 192-250 | private use | This document | 1798 | 251-255 | reserved | This document | 1799 +---------+---------------------------------+---------------+ 1801 Table 4 1803 10. References 1805 10.1. Normative References 1807 [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate 1808 Requirement Levels", BCP 14, RFC 2119, March 1997. 1810 [RFC5050] Scott, K. and S. Burleigh, "Bundle Protocol 1811 Specification", RFC 5050, November 2007. 1813 [RFC5652] Housley, R., "Cryptographic Message Syntax (CMS)", STD 70, 1814 RFC 5652, DOI 10.17487/RFC5652, September 2009, 1815 . 1817 [RFC6255] Blanchet, M., "Delay-Tolerant Networking Bundle Protocol 1818 IANA Registries", RFC 6255, May 2011. 1820 10.2. Informative References 1822 [RFC3986] Berners-Lee, T., Fielding, R., and L. Masinter, "Uniform 1823 Resource Identifier (URI): Generic Syntax", STD 66, RFC 1824 3986, January 2005. 1826 [RFC4838] Cerf, V., Burleigh, S., Hooke, A., Torgerson, L., Durst, 1827 R., Scott, K., Fall, K., and H. Weiss, "Delay-Tolerant 1828 Networking Architecture", RFC 4838, April 2007. 1830 Internet-DrafStreamlined Bundle Security Protocol Specifica October 2015 1832 [RFC5751] Ramsdell, B. and S. Turner, "Secure/Multipurpose Internet 1833 Mail Extensions (S/MIME) Version 3.2 Message 1834 Specification", RFC 5751, January 2010. 1836 [RFC6257] Symington, S., Farrell, S., Weiss, H., and P. Lovell, 1837 "Bundle Security Protocol Specification", RFC 6257, May 1838 2011. 1840 Appendix A. Acknowledgements 1842 The following participants contributed technical material, use cases, 1843 and useful thoughts on the overall approach to this security 1844 specification: Scott Burleigh of the Jet Propulsion Laboratory, Amy 1845 Alford and Angela Hennessy of the Laboratory for Telecommunications 1846 Sciences, and Angela Dalton and Cherita Corbett of the Johns Hopkins 1847 University Applied Physics Laboratory. 1849 Authors' Addresses 1851 Edward J. Birrane, III 1852 The Johns Hopkins University Applied Physics Laboratory 1853 11100 Johns Hopkins Rd. 1854 Laurel, MD 20723 1855 US 1857 Phone: +1 443 778 7423 1858 Email: Edward.Birrane@jhuapl.edu 1860 Jeremy Pierce-Mayer 1861 INSYEN AG 1862 Muenchner Str. 20 1863 Oberpfaffenhofen, Bavaria DE 1864 Germany 1866 Phone: +49 08153 28 2774 1867 Email: jeremy.mayer@insyen.com 1869 Dennis C. Iannicca 1870 NASA Glenn Research Center 1871 21000 Brookpark Rd. 1872 Brook Park, OH 44135 1873 US 1875 Phone: +1-216-433-6493 1876 Email: dennis.c.iannicca@nasa.gov