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Run idnits with the --verbose option for more detailed information about the items above. -------------------------------------------------------------------------------- 2 Internet Engineering Task Force D. Wessels 3 Internet-Draft P. Barber 4 Intended status: Standards Track M. Weinberg 5 Expires: October 30, 2020 Verisign 6 W. Kumari 7 Google 8 W. Hardaker 9 USC/ISI 10 April 28, 2020 12 Message Digest for DNS Zones 13 draft-ietf-dnsop-dns-zone-digest-07 15 Abstract 17 This document describes a protocol and new DNS Resource Record that 18 can be used to provide a cryptographic message digest over DNS zone 19 data. The ZONEMD Resource Record conveys the digest data in the zone 20 itself. When a zone publisher includes an ZONEMD record, recipients 21 can verify the zone contents for accuracy and completeness. This 22 provides assurance that received zone data matches published data, 23 regardless of how the zone data has been transmitted and received. 25 ZONEMD is not designed to replace DNSSEC. Whereas DNSSEC protects 26 individual RRSets (DNS data with fine granularity), ZONEMD protects a 27 zone's data as a whole, whether consumed by authoritative name 28 servers, recursive name servers, or any other applications. 30 As specified at this time, ZONEMD is not designed for use in large, 31 dynamic zones due to the time and resources required for digest 32 calculation. The ZONEMD record described in this document is 33 designed so that new digest schemes may be developed in the future to 34 support large, dynamic zones. 36 Status of This Memo 38 This Internet-Draft is submitted in full conformance with the 39 provisions of BCP 78 and BCP 79. 41 Internet-Drafts are working documents of the Internet Engineering 42 Task Force (IETF). Note that other groups may also distribute 43 working documents as Internet-Drafts. The list of current Internet- 44 Drafts is at https://datatracker.ietf.org/drafts/current/. 46 Internet-Drafts are draft documents valid for a maximum of six months 47 and may be updated, replaced, or obsoleted by other documents at any 48 time. It is inappropriate to use Internet-Drafts as reference 49 material or to cite them other than as "work in progress." 51 This Internet-Draft will expire on October 30, 2020. 53 Copyright Notice 55 Copyright (c) 2020 IETF Trust and the persons identified as the 56 document authors. All rights reserved. 58 This document is subject to BCP 78 and the IETF Trust's Legal 59 Provisions Relating to IETF Documents 60 (https://trustee.ietf.org/license-info) in effect on the date of 61 publication of this document. Please review these documents 62 carefully, as they describe your rights and restrictions with respect 63 to this document. Code Components extracted from this document must 64 include Simplified BSD License text as described in Section 4.e of 65 the Trust Legal Provisions and are provided without warranty as 66 described in the Simplified BSD License. 68 Table of Contents 70 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 3 71 1.1. Motivation . . . . . . . . . . . . . . . . . . . . . . . 4 72 1.2. Design Overview . . . . . . . . . . . . . . . . . . . . . 6 73 1.3. Use Cases . . . . . . . . . . . . . . . . . . . . . . . . 6 74 1.3.1. Root Zone . . . . . . . . . . . . . . . . . . . . . . 6 75 1.3.2. Providers, Secondaries, and Anycast . . . . . . . . . 6 76 1.3.3. Response Policy Zones . . . . . . . . . . . . . . . . 7 77 1.3.4. Centralized Zone Data Service . . . . . . . . . . . . 7 78 1.3.5. General Purpose Comparison Check . . . . . . . . . . 7 79 1.4. Requirements Language . . . . . . . . . . . . . . . . . . 7 80 2. The ZONEMD Resource Record . . . . . . . . . . . . . . . . . 7 81 2.1. Non-apex ZONEMD Records . . . . . . . . . . . . . . . . . 8 82 2.2. ZONEMD RDATA Wire Format . . . . . . . . . . . . . . . . 8 83 2.2.1. The Serial Field . . . . . . . . . . . . . . . . . . 8 84 2.2.2. The Scheme Field . . . . . . . . . . . . . . . . . . 9 85 2.2.3. The Hash Algorithm Field . . . . . . . . . . . . . . 9 86 2.2.4. The Digest Field . . . . . . . . . . . . . . . . . . 9 87 2.3. ZONEMD Presentation Format . . . . . . . . . . . . . . . 9 88 2.4. ZONEMD Example . . . . . . . . . . . . . . . . . . . . . 10 89 3. Calculating the Digest . . . . . . . . . . . . . . . . . . . 10 90 3.1. Add ZONEMD Placeholder . . . . . . . . . . . . . . . . . 10 91 3.2. Optionally Sign the Zone . . . . . . . . . . . . . . . . 10 92 3.3. Canonical Format and Ordering . . . . . . . . . . . . . . 10 93 3.3.1. Order of RRSets Having the Same Owner Name . . . . . 11 94 3.4. Inclusion/Exclusion Rules . . . . . . . . . . . . . . . . 11 95 3.5. Scheme-Specific Processing . . . . . . . . . . . . . . . 11 96 3.5.1. The SIMPLE Scheme . . . . . . . . . . . . . . . . . . 12 97 3.6. Update ZONEMD RR . . . . . . . . . . . . . . . . . . . . 12 98 4. Verifying Zone Digest . . . . . . . . . . . . . . . . . . . . 12 99 5. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 13 100 5.1. ZONEMD RRtype . . . . . . . . . . . . . . . . . . . . . . 14 101 5.2. ZONEMD Scheme . . . . . . . . . . . . . . . . . . . . . . 14 102 5.3. ZONEMD Hash Algorithm . . . . . . . . . . . . . . . . . . 14 103 6. Security Considerations . . . . . . . . . . . . . . . . . . . 15 104 6.1. Attacks Against the Zone Digest . . . . . . . . . . . . . 15 105 6.2. Attacks Utilizing ZONEMD Queries . . . . . . . . . . . . 15 106 6.3. Resilience and Fragility . . . . . . . . . . . . . . . . 15 107 7. Performance Considerations . . . . . . . . . . . . . . . . . 16 108 7.1. SIMPLE SHA384 . . . . . . . . . . . . . . . . . . . . . . 16 109 8. Privacy Considerations . . . . . . . . . . . . . . . . . . . 17 110 9. Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . 17 111 10. Implementation Status . . . . . . . . . . . . . . . . . . . . 17 112 10.1. Authors' Implementation . . . . . . . . . . . . . . . . 17 113 10.2. Shane Kerr's Implementation . . . . . . . . . . . . . . 18 114 10.3. NIC Chile Labs Implementation . . . . . . . . . . . . . 18 115 11. Change Log . . . . . . . . . . . . . . . . . . . . . . . . . 18 116 12. References . . . . . . . . . . . . . . . . . . . . . . . . . 23 117 12.1. Normative References . . . . . . . . . . . . . . . . . . 23 118 12.2. Informative References . . . . . . . . . . . . . . . . . 24 119 Appendix A. Example Zones With Digests . . . . . . . . . . . . . 26 120 A.1. Simple EXAMPLE Zone . . . . . . . . . . . . . . . . . . . 26 121 A.2. Complex EXAMPLE Zone . . . . . . . . . . . . . . . . . . 26 122 A.3. EXAMPLE Zone with multiple digests . . . . . . . . . . . 27 123 A.4. The URI.ARPA Zone . . . . . . . . . . . . . . . . . . . . 28 124 A.5. The ROOT-SERVERS.NET Zone . . . . . . . . . . . . . . . . 31 125 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 33 127 1. Introduction 129 In the DNS, a zone is the collection of authoritative resource 130 records (RRs) sharing a common origin ([RFC8499]). Zones are often 131 stored as files on disk in the so-called master file format 132 [RFC1034]. Zones are generally distributed among name servers using 133 the AXFR [RFC5936], and IXFR [RFC1995] protocols. Zone files can 134 also be distributed outside of the DNS, with such protocols as FTP, 135 HTTP, rsync, and even via email. Currently there is no standard way 136 to verify the authenticity of a stand-alone zone. 138 This document introduces a new RR type that serves as a cryptographic 139 message digest of the data in a zone. It allows a receiver of the 140 zone to verify the zone's authenticity, especially when used in 141 combination with DNSSEC. This technique makes the digest a part of 142 the zone itself, allowing verification the zone as a whole, no matter 143 how it is transmitted. Furthermore, the digest is based on the wire 144 format of zone data. Thus, it is independent of presentation format, 145 such as changes in whitespace, capitalization, and comments. 147 DNSSEC provides three strong security guarantees relevant to this 148 protocol: 150 1. whether or not to expect DNSSEC records in the zone, 152 2. whether or not to expect a ZONEMD record in a signed zone, and 154 3. whether or not the ZONEMD record has been altered since it was 155 signed. 157 This specification is OPTIONAL to implement by both publishers and 158 consumers of zone data. 160 1.1. Motivation 162 The motivation for this protocol enhancement is the desire for the 163 ability to verify the authenticity of a stand-alone zone, regardless 164 of how it is transmitted. A consumer of zone data should be able to 165 verify that the data is as-published by the zone operator. 167 One approach to preventing data tampering and corruption is to secure 168 the distribution channel. The DNS has a number of features that can 169 already be used for channel security. Perhaps the most widely used 170 is DNS transaction signatures (TSIG [RFC2845]). TSIG uses shared 171 secret keys and a message digest to protect individual query and 172 response messages. It is generally used to authenticate and validate 173 UPDATE [RFC2136], AXFR [RFC5936], and IXFR [RFC1995] messages. 175 DNS Request and Transaction Signatures (SIG(0) [RFC2931]) is another 176 protocol extension designed to authenticate individual DNS 177 transactions. Whereas SIG records were originally designed to cover 178 specific RR types, SIG(0) is used to sign an entire DNS message. 179 Unlike TSIG, SIG(0) uses public key cryptography rather than shared 180 secrets. 182 The Transport Layer Security protocol suite is also designed to 183 provide channel security. One can easily imagine the distribution of 184 zones over HTTPS-enabled web servers, as well as DNS-over-HTTPS 185 [RFC8484], and perhaps even a future version of DNS-over-TLS 186 ([RFC7858]). 188 Unfortunately, the protections provided by these channel security 189 techniques are (in practice) ephemeral and are not retained after the 190 data transfer is complete. They can ensure that the client receives 191 the data from the expected server, and that the data sent by the 192 server is not modified during transmission. However, they do not 193 guarantee that the server transmits the data as originally published, 194 and do not provide any methods to verify data that is read after 195 transmission is complete. For example, a name server loading saved 196 zone data upon restart cannot guarantee that the on-disk data has not 197 been modified. For these reasons, it is preferable to secure the 198 data itself. 200 Why not simply rely on DNSSEC, which provides certain data security 201 guarantees? Certainly for zones that are signed, a recipient could 202 validate all of the signed RRSets. Additionally, denial-of-existence 203 records can prove that RRSets have not been added or removed. 204 However, not all RRSets in a zone are signed. The design of DNSSEC 205 stipulates that delegations (non-apex NS records) are not signed, and 206 neither are any glue records. ZONEMD protects the integrity of 207 delegation, glue, and other records that are not otherwise covered by 208 DNSSEC. Furthermore, zones that employ NSEC3 with opt-out are 209 susceptible to the removal or addition of names between the signed 210 nodes. Whereas DNSSEC is primarily designed to protect consumers of 211 DNS response messages, this protocol is designed to protect consumers 212 of zones. 214 There are existing tools and protocols that provide data security, 215 such as OpenPGP [RFC4880] and S/MIME [RFC5751]. In fact, the 216 internic.net site publishes PGP signatures along side the root zone 217 and other files available there. However, this is a detached 218 signature with no strong association to the corresponding zone file 219 other than its timestamp. Non-detached signatures are, of course, 220 possible, but these necessarily change the format of the file being 221 distributed. That is, a zone signed with OpenPGP or S/MIME no longer 222 looks like a DNS zone and could not directly be loaded into a name 223 server. Once loaded the signature data is lost, so it does not 224 survive further propagation. 226 It seems the desire for data security in DNS zones was envisioned as 227 far back as 1997. [RFC2065] is an obsoleted specification of the 228 first generation DNSSEC Security Extensions. It describes a zone 229 transfer signature, aka AXFR SIG, which is similar to the technique 230 proposed by this document. That is, it proposes ordering all 231 (signed) RRSets in a zone, hashing their contents, and then signing 232 the zone hash. The AXFR SIG is described only for use during zone 233 transfers. It did not postulate the need to validate zone data 234 distributed outside of the DNS. Furthermore, its successor, 235 [RFC2535], omits the AXFR SIG, while at the same time introducing an 236 IXFR SIG. 238 1.2. Design Overview 240 This document introduces a new Resource Record type designed to 241 convey a message digest of the content of a zone. The digest is 242 calculated at the time of zone publication. Ideally the zone is 243 signed with DNSSEC to guarantee that any modifications of the digest 244 can be detected. The procedures for digest calculation and DNSSEC 245 signing are similar. Both require data to be processed in a well- 246 defined order and format. In some cases it may be possible to 247 perform DNSSEC signing and digest calculation in parallel. 249 The zone digest is designed to be used on zones that are relatively 250 stable and have infrequent updates. As currently specified, the 251 digest is re-calculated over the entire zone content each time. This 252 specification does not provide an efficient mechanism for incremental 253 updates of zone data. It is, however, extensible so that future 254 schemes to support incremental zone digest algorithms (e.g. using 255 Merkle trees) can be accommodated. 257 It is expected that verification of a zone digest would be 258 implemented in name server software. That is, a name server can 259 verify the zone data it was given and refuse to serve a zone which 260 fails verification. For signed zones, the name server needs a trust 261 anchor to perform DNSSEC validation. For signed non-root zones, the 262 name server may need to send queries to validate a chain-of-trust. 263 Digest verification could also be performed externally. 265 1.3. Use Cases 267 1.3.1. Root Zone 269 The root zone [InterNIC] is one of the most widely distributed DNS 270 zone on the Internet, served by more than 1000 separate instances 271 [RootServers] at the time of this writing. Additionally, many 272 organizations configure their own name servers to serve the root zone 273 locally. Reasons for doing so include privacy and reduced access 274 time. [RFC7706] describes one, but not the only, way to do this. As 275 the root zone spreads beyond its traditional deployment boundaries, 276 the need for verification of the completeness of the zone contents 277 becomes increasingly important. 279 1.3.2. Providers, Secondaries, and Anycast 281 Since its very early days, the developers of the DNS recognized the 282 importance of secondary name servers and service diversity. However, 283 they may not have anticipated the complexity of modern DNS service 284 provisioning which can include multiple third-party providers and 285 hundreds of anycast instances. Instead of a simple primary-to- 286 secondary zone distribution system, today it is possible to have 287 multiple levels, multiple parties, and multiple protocols involved in 288 the distribution of zone data. This complexity introduces new places 289 for problems to arise. The zone digest protects the integrity of 290 data that flows through such systems. 292 1.3.3. Response Policy Zones 294 DNS Response Policy Zones is "a method of expressing DNS response 295 policy information inside specially constructed DNS zones..." [RPZ]. 296 A number of companies provide RPZ feeds, which can be consumed by 297 name server and firewall products. Since these are zones, AXFR is 298 often, but not necessarily used for transmission. While RPZ zones 299 can certainly be signed with DNSSEC, the data is not queried 300 directly, and would not be subject to DNSSEC validation. 302 1.3.4. Centralized Zone Data Service 304 ICANN operates the Centralized Zone Data Service [CZDS], which is a 305 repository of top-level domain zone files. Users request access to 306 the system, and to individual zones, and are then able to download 307 zone data for certain uses. Adding a zone digest to these would 308 provide CZDS users with assurances that the data has not been 309 modified. Note that ZONEMD could be added to CZDS zone data 310 independently of the zone served by production name servers. 312 1.3.5. General Purpose Comparison Check 314 Since the zone digest calculation does not depend on presentation 315 format, it could be used to compare multiple copies of a zone 316 received from different sources, or copies generated by different 317 processes. 319 1.4. Requirements Language 321 The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", 322 "SHOULD", "SHOULD NOT", "RECOMMENDED", "NOT RECOMMENDED", "MAY", and 323 "OPTIONAL" in this document are to be interpreted as described in BCP 324 14 [RFC2119] [RFC8174] when, and only when, they appear in all 325 capitals, as shown here. 327 2. The ZONEMD Resource Record 329 This section describes the ZONEMD Resource Record, including its 330 fields, wire format, and presentation format. The Type value for the 331 ZONEMD RR is 63. The ZONEMD RR is class independent. The RDATA of 332 the resource record consists of four fields: Serial, Scheme, Hash 333 Algorithm, and Digest. 335 A zone MAY contain multiple ZONEMD RRs to support algorithm agility 336 [RFC7696] and rollovers. Each ZONEMD RR must specify a unique Scheme 337 and Hash Algorithm tuple. It is recommended that a zone include only 338 one ZONEMD RR, unless the zone publisher is in the process of 339 transitioning to a new Scheme or Hash Algorithm. 341 2.1. Non-apex ZONEMD Records 343 This specification utilizes ZONEMD RRs located at the zone apex. 344 Non-apex ZONEMD RRs are not forbidden, but have no meaning in this 345 specification. Non-apex ZONEMD RRs MUST NOT be used for 346 verification. 348 During digest calculation, non-apex ZONEMD RRs are treated like any 349 other RRs. They are digested as-is and the RR is not replaced by a 350 placeholder RR. 352 Unless explicitly stated otherwise, "ZONEMD" always refers to apex 353 records throughout this document. 355 2.2. ZONEMD RDATA Wire Format 357 The ZONEMD RDATA wire format is encoded as follows: 359 1 1 1 1 1 1 1 1 1 1 2 2 2 2 2 2 2 2 2 2 3 3 360 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 361 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 362 | Serial | 363 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 364 | Scheme |Hash Algorithm | | 365 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | 366 | Digest | 367 / / 368 / / 369 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 371 2.2.1. The Serial Field 373 The Serial field is a 32-bit unsigned integer in network order. It 374 is equal to the serial number from the zone's SOA record ([RFC1035] 375 section 3.3.13) for which the zone digest was generated. 377 The zone's serial number is included here in order to make DNS 378 response messages of type ZONEMD meaningful. Without the serial 379 number, a stand-alone ZONEMD digest has no association to any 380 particular instance of a zone. 382 2.2.2. The Scheme Field 384 The Scheme field is an 8-bit unsigned integer that identifies the 385 methods by which data is collated and presented as input to the 386 hashing function. 388 At the time of this writing, SIMPLE, with value 1, is the only 389 standardized Scheme defined for ZONEMD records. The Scheme registry 390 is further described in Section 5. 392 Scheme values 240-254 are allocated for Private Use as described in 393 [RFC8126]. 395 2.2.3. The Hash Algorithm Field 397 The Hash Algorithm field is an 8-bit unsigned integer that identifies 398 the cryptographic hash algorithm used to construct the digest. 400 At the time of this writing, SHA384, with value 1, is the only 401 standardized Hash Algorithm defined for ZONEMD records. The Hash 402 Algorithm registry is further described in Section 5. 404 Hash Algorithm values 240-254 are allocated for Private Use as 405 described in [RFC8126]. 407 2.2.4. The Digest Field 409 The Digest field is a variable-length sequence of octets containing 410 the output of the hash algorithm. The Digest field must not be 411 empty. Section 3 describes how to calculate the digest for a zone. 412 Section 4 describes how to use the digest to verify the contents of a 413 zone. 415 2.3. ZONEMD Presentation Format 417 The presentation format of the RDATA portion is as follows: 419 The Serial field is represented as an unsigned decimal integer. 421 The Scheme field is represented as an unsigned decimal integer. 423 The Hash Algorithm field is represented as an unsigned decimal 424 integer. 426 The Digest is represented as a sequence of case-insensitive 427 hexadecimal digits. Whitespace is allowed within the hexadecimal 428 text. 430 2.4. ZONEMD Example 432 The following example shows a ZONEMD RR. 434 example.com. 86400 IN ZONEMD 2018031500 1 1 ( 435 FEBE3D4CE2EC2FFA4BA99D46CD69D6D29711E55217057BEE 436 7EB1A7B641A47BA7FED2DD5B97AE499FAFA4F22C6BD647DE ) 438 3. Calculating the Digest 440 3.1. Add ZONEMD Placeholder 442 In preparation for calculating the zone digest, any existing ZONEMD 443 records (and covering RRSIGs) at the zone apex are first deleted. 445 Prior to calculation of the digest, and prior to signing with DNSSEC, 446 one or more placeholder ZONEMD records are added to the zone apex. 447 This ensures that appropriate denial-of-existence (NSEC, NSEC3) 448 records are created if the zone is signed with DNSSEC. When multiple 449 ZONEMD RRs are published in the zone, e.g., during an algorithm 450 rollover, each must specify a unique Scheme and Hash Algorithm tuple. 452 It is recommended that the TTL of the ZONEMD record match the TTL of 453 the SOA. 455 In the placeholder record, the Serial field is set to the current SOA 456 Serial. The Scheme field is set to the value for the chosen 457 collation scheme. The Hash Algorithm field is set to the value for 458 the chosen hash algorithm. Since ZONEMD records are excluded from 459 digest calculation, the value of the Digest field does not matter at 460 this point in the process. Implementations MAY want to set the 461 Digest field to all zeroes anyway. 463 3.2. Optionally Sign the Zone 465 Following addition of placeholder records, the zone may be signed 466 with DNSSEC. Note that when the digest calculation is complete, and 467 the ZONEMD record is updated, the signature(s) for the ZONEMD RRSet 468 MUST be recalculated and updated as well. Therefore, the signer is 469 not required to calculate a signature over the placeholder record at 470 this step in the process, but it is harmless to do so. 472 3.3. Canonical Format and Ordering 474 Calculation of a zone digest REQUIRES RRs to be processed in a 475 consistent format and ordering. Correct ordering depends on (1) 476 ordering of owner names, (2) ordering of RRSets with the same owner 477 name, and (3) ordering of RRs within an RRSet. 479 This specification adopts DNSSEC's canonical ordering for names 480 (Section 6.1 of [RFC4034]), and canonical ordering for RRs within an 481 RRSet (Section 6.3 of [RFC4034]). It also adopts DNSSEC's canonical 482 RR form (Section 6.2 of [RFC4034]). However, since DNSSEC does not 483 define a canonical ordering for RRSets having the same owner name, 484 that ordering is defined here. 486 This specification adopts DNSSEC's canonical on-the-wire RR format 487 (without name compression) as specified in [RFC4034]: 489 RR(i) = owner | type | class | TTL | RDATA length | RDATA 491 where "|" denotes concatenation. 493 3.3.1. Order of RRSets Having the Same Owner Name 495 For the purposes of calculating the zone digest, RRSets having the 496 same owner name MUST be numerically ordered, in ascending order, by 497 their numeric RR TYPE. 499 3.4. Inclusion/Exclusion Rules 501 When iterating over records in the zone, the following inclusion/ 502 exclusion rules apply: 504 o All records in the zone, including glue records, MUST be included. 506 o Occluded data ([RFC5936] Section 3.5) MUST be included. 508 o Only one instance of duplicate RRs with equal owner, class, type 509 and RDATA SHALL be included ([RFC4034] Section 6.3). 511 o The placeholder ZONEMD RR(s) MUST NOT be included. 513 o If the zone is signed, DNSSEC RRs MUST be included, except: 515 o The RRSIG covering ZONEMD MUST NOT be included because the RRSIG 516 will be updated after all digests have been calculated. 518 3.5. Scheme-Specific Processing 520 At this time, only the SIMPLE collation scheme is defined. 521 Additional schemes may be defined in future updates to this document. 523 3.5.1. The SIMPLE Scheme 525 For the SIMPLE scheme, the digest is calculated over the zone as a 526 whole. This means that a change to a single RR in the zone requires 527 iterating over all RRs in the zone to recalculate the digest. SIMPLE 528 is a good choice for zones that are small and/or stable, but probably 529 not good for zones that are large and/or dynamic. 531 A zone digest using the SIMPLE scheme is calculated by concatenating 532 the canonical form of all RRs in the zone, in the order described in 533 Section 3.3, subject to the inclusion/exclusion rules described in 534 Section 3.4, and then applying the SHA-384 algorithm: 536 digest = hash( RR(1) | RR(2) | RR(3) | ... ) 538 where "|" denotes concatenation. 540 3.6. Update ZONEMD RR 542 Once a zone digest has been calculated, the published ZONEMD record 543 is finalised by inserting the digest into the placeholder ZONEMD. 544 Repeat for each digest if multiple digests are to be published. 546 If the zone is signed with DNSSEC, the RRSIG record(s) covering the 547 ZONEMD RRSet MUST then be added or updated. Because the ZONEMD 548 placeholder was added prior to signing, the zone will already have 549 the appropriate denial-of-existence (NSEC, NSEC3) records. 551 Some DNSSEC implementations (especially "online signing") might be 552 designed such that the SOA serial number is updated whenever a new 553 signature is made. To preserve the calculated digest, generation of 554 an ZONEMD signature must not also result in a change to the SOA 555 serial number. The ZONEMD RR and the matching SOA MUST be published 556 at the same time. 558 4. Verifying Zone Digest 560 The recipient of a zone that has a ZONEMD RR can verify the zone by 561 calculating the digest as follows. If multiple ZONEMD RRs are 562 present in the zone, e.g., during an algorithm rollover, a match 563 using any one of the recipient's supported Schemes and Hash 564 Algorithms is sufficient to verify the zone. 566 1. The verifier MUST first determine whether or not to expect DNSSEC 567 records in the zone. This can be done by examining locally 568 configured trust anchors, or querying for (and validating) DS RRs 569 in the parent zone. For zones that are provably insecure, or if 570 DNSSEC validation can not be performed, digest validation 571 continues at step 4 below. 573 2. For zones that are provably secure, the existence of the apex 574 ZONEMD record MUST be verified. If the ZONEMD record provably 575 does not exist, digest verification cannot be done. If the 576 ZONEMD record does provably exist, but is not found in the zone, 577 digest verification MUST NOT be considered successful. 579 3. For zones that are provably secure, the SOA and ZONEMD RRSets 580 MUST have valid signatures, chaining up to a trust anchor. If 581 DNSSEC validation of the SOA or ZONEMD records fails, digest 582 verification MUST NOT be considered successful. 584 4. If the ZONEMD RRSet contains more than one RR with the same 585 Scheme and Hash Algorithm, digest verification MUST NOT be 586 considered successful. 588 5. Loop over all apex ZONEMD RRs and perform the following steps: 590 A. The SOA Serial field MUST exactly match the ZONEMD Serial 591 field. If the fields do not match, digest verification MUST 592 NOT be considered successful with this ZONEMD RR. 594 B. The Scheme field MUST be checked. If the verifier does not 595 support the given scheme, it SHOULD report that the RR's 596 digest could not be verified due to an unsupported scheme. 598 C. The Hash Algorithm field MUST be checked. If the verifier 599 does not support the given hash algorithm, it SHOULD report 600 that the RR's digest could not be verified due to an 601 unsupported algorithm. 603 D. The zone digest is computed over the zone data as described 604 in Section 3.5, using the Scheme and Hash Algorithm for the 605 current ZONEMD RR. 607 E. The computed digest is compared to the received digest. If 608 the two digest values match, verification is considered 609 successful. Otherwise, verification MUST NOT be considered 610 successful for this ZONEMD RR. 612 5. IANA Considerations 613 5.1. ZONEMD RRtype 615 This document defines a new DNS RR type, ZONEMD, whose value 63 has 616 been allocated by IANA from the "Resource Record (RR) TYPEs" 617 subregistry of the "Domain Name System (DNS) Parameters" registry: 619 Type: ZONEMD 621 Value: 63 623 Meaning: Message Digest Over Zone Data 625 Reference: This document 627 5.2. ZONEMD Scheme 629 This document asks IANA to create a new "ZONEMD Scheme" registry with 630 initial contents as follows: 632 +---------+--------------------+----------+-----------+-------------+ 633 | Value | Description | Mnemonic | Status | Reference | 634 +---------+--------------------+----------+-----------+-------------+ 635 | 0 | Reserved | RESERVED | N/A | N/A | 636 | 1 | Simple ZONEMD | SIMPLE | Mandatory | This | 637 | | collation | | | document | 638 | 240-254 | Private Use | N/A | N/A | [RFC8126] | 639 +---------+--------------------+----------+-----------+-------------+ 641 Table 1: ZONEMD Scheme Registry 643 The IANA policy for assigning new values to the ZONEMD Scheme 644 registry shall be Specification Required, as described in [RFC8126]. 646 5.3. ZONEMD Hash Algorithm 648 This document asks IANA to create a new "ZONEMD Hash Algorithm" 649 registry with initial contents as follows: 651 +---------+----------------------+----------+-----------+-----------+ 652 | Value | Description | Mnemonic | Status | Reference | 653 +---------+----------------------+----------+-----------+-----------+ 654 | 0 | Reserved | RESERVED | N/A | N/A | 655 | 1 | The SHA-384 hash | SHA384 | Mandatory | [RFC6234] | 656 | | algorithm | | | | 657 | 240-254 | Private Use | N/A | N/A | [RFC8126] | 658 +---------+----------------------+----------+-----------+-----------+ 660 Table 2: ZONEMD Hash Algorithm Registry 662 The IANA policy for assigning new values to the ZONEMD Hash Algorithm 663 registry shall be Specification Required, as described in [RFC8126]. 665 6. Security Considerations 667 6.1. Attacks Against the Zone Digest 669 The zone digest allows the receiver to verify that the zone contents 670 haven't been modified since the zone was generated/published. 671 Verification is strongest when the zone is also signed with DNSSEC. 672 An attacker, whose goal is to modify zone content before it is used 673 by the victim, may consider a number of different approaches. 675 The attacker might perform a downgrade attack to an unsigned zone. 676 This is why Section 4 talks about determining whether or not to 677 expect DNSSEC signatures for the zone in step 1. 679 The attacker might perform a downgrade attack by removing one or more 680 ZONEMD records. Such a removal is detectable only with DNSSEC 681 validation and is why Section 4 talks about checking denial-of- 682 existence proofs in step 2 and signature validation in step 3. 684 The attacker might alter the Scheme, Hash Algorithm, or Digest fields 685 of the ZONEMD record. Such modifications are detectable only with 686 DNSSEC validation. 688 6.2. Attacks Utilizing ZONEMD Queries 690 Nothing in this specification prevents clients from making, and 691 servers from responding to, ZONEMD queries. Servers SHOULD NOT 692 calculate zone digests dynamically (for each query) as this can be 693 used as a CPU resource exhaustion attack. 695 One might consider how well ZONEMD responses could be used in a 696 distributed denial-of-service amplification attack. The ZONEMD RR is 697 moderately sized, much like the DS RR. A single ZONEMD RR 698 contributes approximately 40 to 65 octets to a DNS response, for 699 currently defined digest types. Certainly other RR types result in 700 larger amplification effects (i.e., DNSKEY). 702 6.3. Resilience and Fragility 704 ZONEMD can be used to detect incomplete or corrupted zone data prior 705 to its use, thereby increasing resilience, but also introducing some 706 fragility. Publishers and consumers of zones containing ZONEMD 707 records should be aware of these tradeoffs. While the intention is 708 to secure the zone data, misconfigurations or implementation bugs are 709 generally indistinguishable from intentional tampering, and could 710 lead to service failures when verification is performed 711 automatically. 713 Zone publishers may want to deploy ZONEMD gradually, perhaps by 714 utilizing one of the private use hash algorithms listed in 715 Section 5.3. Similarly, recipients may want to initially configure 716 verification failures only as a warning, and later as an error after 717 gaining experience and confidence with the feature. 719 7. Performance Considerations 721 This section is provided to make zone publishers aware of the 722 performance requirements and implications of including ZONEMD RRs in 723 a zone. 725 7.1. SIMPLE SHA384 727 As mentioned previously, the SIMPLE scheme may not be appropriate for 728 use in zones that are either large or highly dynamic. Zone 729 publishers should carefully consider the use of ZONEMD in such zones, 730 since it might cause consumers of zone data (e.g., secondary name 731 servers) to expend resources on digest calculation. Furthermore, for 732 such use cases, it is recommended that ZONEMD only be used when 733 digest calculation time is significantly less than propagation times 734 and update intervals. 736 The authors' implementation (Section 10.1) includes an option to 737 record and report CPU usage of its operation. The software was used 738 to generate digests for more than 800 TLD zones available from 739 [CZDS]. The table below summarizes the the results for the SIMPLE 740 scheme and SHA384 hash algorithm grouped by zone size. The Rate 741 column is the mean amount of time per RR to calculate the digest, 742 running on commodity hardware at the time of this writing. 744 +---------------------+----------------+ 745 | Zone Size (RRs) | Rate (msec/RR) | 746 +---------------------+----------------+ 747 | 10 - 99 | 0.00683 | 748 | 100 - 999 | 0.00551 | 749 | 1000 - 9999 | 0.00505 | 750 | 10000 - 99999 | 0.00602 | 751 | 100000 - 999999 | 0.00845 | 752 | 1000000 - 9999999 | 0.0108 | 753 | 10000000 - 99999999 | 0.0148 | 754 +---------------------+----------------+ 756 For example, based on the above table, it takes approximately 0.13 757 seconds to calculate a SIMPLE SHA384 digest for a zone with 22,000 758 RRs, and about 2.5 seconds for a zone with 300,000 RRs. 760 These benchmarks attempt to emulate a worst-case scenario and take 761 into account the time required to canonicalize the zone for 762 processing. Each of the 800+ zones were measured three times, and 763 then averaged, with a different random sorting of the input data 764 prior to each measurement. 766 8. Privacy Considerations 768 This specification has no impact on user privacy. 770 9. Acknowledgments 772 The authors wish to thank David Blacka, Scott Hollenbeck, and Rick 773 Wilhelm for providing feedback on early drafts of this document. 774 Additionally, they thank Joe Abley, Mark Andrews, Ralph Dolmans, 775 Richard Gibson, Olafur Gudmundsson, Bob Harold, Paul Hoffman, Evan 776 Hunt, Shumon Huque, Tatuya Jinmei, Mike St. Johns, Burt Kaliski, 777 Shane Kerr, Matt Larson, John Levine, Ed Lewis, Matt Pounsett, Mukund 778 Sivaraman, Petr Spacek, Ondrej Sury, Willem Toorop, Florian Weimer, 779 Tim Wicinksi, Wouter Wijngarrds, Paul Wouters, and other members of 780 the dnsop working group for their input. 782 10. Implementation Status 784 10.1. Authors' Implementation 786 The authors have an open source implementation in C, using the ldns 787 library [ldns-zone-digest]. This implementation is able to perform 788 the following functions: 790 o Read an input zone and output a zone with the ZONEMD placeholder. 792 o Compute zone digest over signed zone and update the ZONEMD record. 794 o Re-compute DNSSEC signature over the ZONEMD record. 796 o Verify the zone digest from an input zone. 798 This implementation does not: 800 o Perform DNSSEC validation of the ZONEMD record during 801 verification. 803 10.2. Shane Kerr's Implementation 805 Shane Kerr wrote an implementation of this specification during the 806 IETF 102 hackathon [ZoneDigestHackathon]. This implementation is in 807 Python and is able to perform the following functions: 809 o Read an input zone and output a zone with ZONEMD record. 811 o Verify the zone digest from an input zone. 813 o Output the ZONEMD record in its defined presentation format. 815 This implementation does not: 817 o Re-compute DNSSEC signature over the ZONEMD record. 819 o Perform DNSSEC validation of the ZONEMD record. 821 10.3. NIC Chile Labs Implementation 823 NIC Chile Labs wrote an implementation of this specification as part 824 of "dns-tools" suite [DnsTools], which besides digesting, can also 825 sign and verify zones. This implementation is in Go and is able to 826 perform the following functions: 828 o Compute zone digest over signed zone and update the ZONEMD record. 830 o Verify the zone digest from an input zone. 832 o Perform DNSSEC validation of the ZONEMD record during 833 verification. 835 o Re-compute DNSSEC signature over the ZONEMD record. 837 11. Change Log 839 RFC Editor: Please remove this section. 841 This section lists substantial changes to the document as it is being 842 worked on. 844 From -00 to -01: 846 o Removed requirement to sort by RR CLASS. 848 o Added Kumari and Hardaker as coauthors. 850 o Added Change Log section. 852 o Minor clarifications and grammatical edits. 854 From -01 to -02: 856 o Emphasize desire for data security over channel security. 858 o Expanded motivation into its own subsection. 860 o Removed discussion topic whether or not to include serial in 861 ZONEMD. 863 o Clarified that a zone's NS records always sort before the SOA 864 record. 866 o Clarified that all records in the zone must are digested, except 867 as specified in the exclusion rules. 869 o Added for discussion out-of-zone and occluded records. 871 o Clarified that update of ZONEMD signature must not cause a serial 872 number change. 874 o Added persons to acknowledgments. 876 From -02 to -03: 878 o Added recommendation to set ZONEMD TTL to SOA TTL. 880 o Clarified that digest input uses uncompressed names. 882 o Updated Implementations section. 884 o Changed intended status from Standards Track to Experimental and 885 added Scope of Experiment section. 887 o Updated Motivation, Introduction, and Design Overview sections in 888 response to working group discussion. 890 o Gave ZONEMD digest types their own status, separate from DS digest 891 types. Request IANA to create a registry. 893 o Added Reserved field for future work supporting dynamic updates. 895 o Be more rigorous about having just ONE ZONEMD record in the zone. 897 o Expanded use cases. 899 From -03 to -04: 901 o Added an appendix with example zones and digests. 903 o Clarified that only apex ZONEMD RRs shall be processed. 905 From -04 to -05: 907 o Made SHA384 the only supported ZONEMD digest type. 909 o Disassociated ZONEMD digest types from DS digest types. 911 o Updates to Introduction based on list feedback. 913 o Changed "zone file" to "zone" everywhere. 915 o Restored text about why ZONEMD has a Serial field. 917 o Clarified ordering of RRSets having same owner to be numerically 918 ascending. 920 o Clarified that all duplicate RRs (not just SOA) must be suppressed 921 in digest calculation. 923 o Clarified that the Reserved field must be set to zero and checked 924 for zero in verification. 926 o Clarified that occluded data must be included. 928 o Clarified procedure for verification, using temporary location for 929 received digest. 931 o Explained why Reserved field is 8-bits. 933 o IANA Considerations section now more specific. 935 o Added complex zone to examples. 937 o 939 From -05 to -06: 941 o RR type code 63 was assigned to ZONEMD by IANA. 943 From -06 to -07: 945 o Fixed mistakes in ZONEMD examples. 947 o Added private use Digest Type values 240-254. 949 o Clarified that Digest field must not be empty. 951 From -07 to draft-ietf-dnsop-dns-zone-digest-00: 953 o Adopted by dnsop. 955 o Clarified further that non-apex ZONEMD RRs have no meaning. 957 o Changed "provably [un]signed" to "provably [in]secure". 959 o Allow multiple ZONEMD RRs to support algorithm agility/rollovers. 961 o Describe verification when there are multiple ZONEMD RRs. 963 From -00 to -01: 965 o Simplified requirements around verifying multiple digests. Any 966 one match is sufficient. 968 o Updated implementation notes. 970 o Both implementations produce expected results on examples given in 971 this document. 973 From -01 to -02: 975 o Changed the name of the Reserved field to Parameter. 977 o Changed the name of Digest Type 1 from SHA384 to SHA384-STABLE. 979 o The meaning of the Parameter field now depends on Digest Type. 981 o No longer require Parameter field to be zero in verification. 983 o Updated a rule from earlier versions that said multiple ZONEMD RRs 984 were not allowed. 986 From -02 to -03: 988 o Changed the name of Digest Type 1 from SHA384-STABLE to 989 SHA384-SIMPLE. 991 o Changed document status from Experimental to Standards Track. 993 o Removed Scope of Experimentation section. 995 From -03 to -04: 997 o Addressing WGLC feedback. 999 o Changed from "Digest Type + Paramter" to "Scheme + Hash 1000 Algorithm". This should make it more obvious how ZONEMD can be 1001 expanded in the future with new schemes and hash algorithms, while 1002 sacrificing some of the flexibility that the Parameter was 1003 intended to provide. 1005 o Note: old RDATA fields: Serial, Digest Type, Parameter, Digest. 1007 o Note: new RDATA fields: Serial, Scheme, Hash Algorithm, Digest. 1009 o Add new IANA requirement for a Scheme registry. 1011 o Rearranged some sections and separated scheme-specific aspects 1012 from general aspects of digest calculation. 1014 o When discussing multiple ZONEMD RRs, allow for Scheme, as well as 1015 Hash Algorithm, transition. 1017 o Added Performance Considerations section with some benchmarks. 1019 o Further clarifications about non-apex ZONEMD RRs. 1021 o Clarified inclusion rule for duplicate RRs. 1023 o Removed or lowercased some inappropriately used RFC 2119 key 1024 words. 1026 o Clarified that all ZONEMD RRs, even for unsupported hash 1027 algorithms, must be zeroized during digest calculation. 1029 o Added Resilience and Fragility to security considerations. 1031 o Updated examples since changes in this version result in different 1032 hash values. 1034 From -04 to -05: 1036 o Clarifications about non-apex and multiple ZONEMD RRs. 1038 o Clarifications about benchmark results. 1040 o Don't compute ZONEMD on-the-fly. 1042 o Specifciation Required for updates to ZONEMD protocol registries. 1044 o Other rewording based on WGLC feedback. 1046 o Updated RFC numbers for some references. 1048 o Use documentation IP addresses instead of loopback. 1050 o Updated examples in the appendix. 1052 From -05 to -06: 1054 o Per WG suggestion, no longer include any apex ZONEMD record in 1055 digest calculation. 1057 o Updated examples in the appendix. 1059 o Clarified verification procedure by describing a loop over all 1060 ZONEMD RRs. 1062 From -06 to -07: 1064 o Added NIC Chile Labs implementation. 1066 12. References 1068 12.1. Normative References 1070 [RFC1034] Mockapetris, P., "Domain names - concepts and facilities", 1071 STD 13, RFC 1034, DOI 10.17487/RFC1034, November 1987, 1072 . 1074 [RFC1035] Mockapetris, P., "Domain names - implementation and 1075 specification", STD 13, RFC 1035, DOI 10.17487/RFC1035, 1076 November 1987, . 1078 [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate 1079 Requirement Levels", BCP 14, RFC 2119, 1080 DOI 10.17487/RFC2119, March 1997, 1081 . 1083 [RFC4034] Arends, R., Austein, R., Larson, M., Massey, D., and S. 1084 Rose, "Resource Records for the DNS Security Extensions", 1085 RFC 4034, DOI 10.17487/RFC4034, March 2005, 1086 . 1088 [RFC6234] Eastlake 3rd, D. and T. Hansen, "US Secure Hash Algorithms 1089 (SHA and SHA-based HMAC and HKDF)", RFC 6234, 1090 DOI 10.17487/RFC6234, May 2011, 1091 . 1093 [RFC8174] Leiba, B., "Ambiguity of Uppercase vs Lowercase in RFC 1094 2119 Key Words", BCP 14, RFC 8174, DOI 10.17487/RFC8174, 1095 May 2017, . 1097 12.2. Informative References 1099 [CZDS] Internet Corporation for Assigned Names and Numbers, 1100 "Centralized Zone Data Service", October 2018, 1101 . 1103 [DnsTools] 1104 NIC Chile Labs, "DNS tools for zone signature (file, 1105 pkcs11-hsm) and validation, and zone digest (ZONEMD)", 1106 April 2020, . 1108 [InterNIC] 1109 ICANN, "InterNIC FTP site", May 2018, 1110 . 1112 [ldns-zone-digest] 1113 Verisign, "Implementation of Message Digests for DNS Zones 1114 using the ldns library", July 2018, 1115 . 1117 [RFC1995] Ohta, M., "Incremental Zone Transfer in DNS", RFC 1995, 1118 DOI 10.17487/RFC1995, August 1996, 1119 . 1121 [RFC2065] Eastlake 3rd, D. and C. Kaufman, "Domain Name System 1122 Security Extensions", RFC 2065, DOI 10.17487/RFC2065, 1123 January 1997, . 1125 [RFC2136] Vixie, P., Ed., Thomson, S., Rekhter, Y., and J. Bound, 1126 "Dynamic Updates in the Domain Name System (DNS UPDATE)", 1127 RFC 2136, DOI 10.17487/RFC2136, April 1997, 1128 . 1130 [RFC2535] Eastlake 3rd, D., "Domain Name System Security 1131 Extensions", RFC 2535, DOI 10.17487/RFC2535, March 1999, 1132 . 1134 [RFC2845] Vixie, P., Gudmundsson, O., Eastlake 3rd, D., and B. 1135 Wellington, "Secret Key Transaction Authentication for DNS 1136 (TSIG)", RFC 2845, DOI 10.17487/RFC2845, May 2000, 1137 . 1139 [RFC2931] Eastlake 3rd, D., "DNS Request and Transaction Signatures 1140 ( SIG(0)s )", RFC 2931, DOI 10.17487/RFC2931, September 1141 2000, . 1143 [RFC4880] Callas, J., Donnerhacke, L., Finney, H., Shaw, D., and R. 1144 Thayer, "OpenPGP Message Format", RFC 4880, 1145 DOI 10.17487/RFC4880, November 2007, 1146 . 1148 [RFC5751] Ramsdell, B. and S. Turner, "Secure/Multipurpose Internet 1149 Mail Extensions (S/MIME) Version 3.2 Message 1150 Specification", RFC 5751, DOI 10.17487/RFC5751, January 1151 2010, . 1153 [RFC5936] Lewis, E. and A. Hoenes, Ed., "DNS Zone Transfer Protocol 1154 (AXFR)", RFC 5936, DOI 10.17487/RFC5936, June 2010, 1155 . 1157 [RFC7696] Housley, R., "Guidelines for Cryptographic Algorithm 1158 Agility and Selecting Mandatory-to-Implement Algorithms", 1159 BCP 201, RFC 7696, DOI 10.17487/RFC7696, November 2015, 1160 . 1162 [RFC7706] Kumari, W. and P. Hoffman, "Decreasing Access Time to Root 1163 Servers by Running One on Loopback", RFC 7706, 1164 DOI 10.17487/RFC7706, November 2015, 1165 . 1167 [RFC7858] Hu, Z., Zhu, L., Heidemann, J., Mankin, A., Wessels, D., 1168 and P. Hoffman, "Specification for DNS over Transport 1169 Layer Security (TLS)", RFC 7858, DOI 10.17487/RFC7858, May 1170 2016, . 1172 [RFC8126] Cotton, M., Leiba, B., and T. Narten, "Guidelines for 1173 Writing an IANA Considerations Section in RFCs", BCP 26, 1174 RFC 8126, DOI 10.17487/RFC8126, June 2017, 1175 . 1177 [RFC8484] Hoffman, P. and P. McManus, "DNS Queries over HTTPS 1178 (DoH)", RFC 8484, DOI 10.17487/RFC8484, October 2018, 1179 . 1181 [RFC8499] Hoffman, P., Sullivan, A., and K. Fujiwara, "DNS 1182 Terminology", BCP 219, RFC 8499, DOI 10.17487/RFC8499, 1183 January 2019, . 1185 [RootServers] 1186 Root Server Operators, "Root Server Technical Operations", 1187 July 2018, . 1189 [RPZ] Vixie, P. and V. Schryver, "DNS Response Policy Zones 1190 (RPZ)", draft-vixie-dnsop-dns-rpz-00 (work in progress), 1191 June 2018, . 1194 [ZoneDigestHackathon] 1195 Kerr, S., "Prototype implementation of ZONEMD for the IETF 1196 102 hackathon in Python", July 2018, 1197 . 1199 Appendix A. Example Zones With Digests 1201 This appendix contains example zones with accurate ZONEMD records. 1202 These can be used to verify an implementation of the zone digest 1203 protocol. 1205 A.1. Simple EXAMPLE Zone 1207 Here, the EXAMPLE zone contains an SOA record, NS and glue records, 1208 and a ZONEMD record. 1210 example. 86400 IN SOA ns1 admin 2018031900 ( 1211 1800 900 604800 86400 ) 1212 86400 IN NS ns1 1213 86400 IN NS ns2 1214 86400 IN ZONEMD 2018031900 1 1 ( 1215 c68090d90a7aed71 1216 6bc459f9340e3d7c 1217 1370d4d24b7e2fc3 1218 a1ddc0b9a87153b9 1219 a9713b3c9ae5cc27 1220 777f98b8e730044c ) 1221 ns1 3600 IN A 203.0.113.63 1222 ns2 3600 IN AAAA 2001:db8::63 1224 A.2. Complex EXAMPLE Zone 1226 Here, the EXAMPLE zone contains duplicate RRs, and an occluded RR, 1227 and one out-of-zone RR. 1229 example. 86400 IN SOA ns1 admin 2018031900 ( 1230 1800 900 604800 86400 ) 1231 86400 IN NS ns1 1232 86400 IN NS ns2 1233 86400 IN ZONEMD 2018031900 1 1 ( 1234 31cefb03814f5062 1235 ad12fa951ba0ef5f 1236 8da6ae354a415767 1237 246f7dc932ceb1e7 1238 42a2108f529db6a3 1239 3a11c01493de358d ) 1240 ns1 3600 IN A 203.0.113.63 1241 ns2 3600 IN AAAA 2001:db8::63 1242 occluded.sub 7200 IN TXT "I'm occluded but must be digested" 1243 sub 7200 IN NS ns1 1244 duplicate 300 IN TXT "I must be digested just once" 1245 duplicate 300 IN TXT "I must be digested just once" 1246 foo.test. 555 IN TXT "out-of-zone data must be excluded" 1247 non-apex 900 IN ZONEMD 2018031900 1 1 ( 1248 616c6c6f77656420 1249 6275742069676e6f 1250 7265642e20616c6c 1251 6f77656420627574 1252 2069676e6f726564 1253 2e20616c6c6f7765 ) 1255 A.3. EXAMPLE Zone with multiple digests 1257 Here, the EXAMPLE zone contains multiple ZONEMD records. Since only 1258 one Scheme (SIMPLE) and one Hash Algorithm (SHA384) is defined at 1259 this time, this example utilizes additional ZONEMD records with 1260 Scheme and Hash Algorithm values in the private range (240-254). 1261 These additional private-range digests are not verifiable. 1263 example. 86400 IN SOA ns1 admin 2018031900 ( 1264 1800 900 604800 86400 ) 1265 example. 86400 IN NS ns1.example. 1266 example. 86400 IN NS ns2.example. 1267 example. 86400 IN ZONEMD 2018031900 1 1 ( 1268 62e6cf51b02e54b9 1269 b5f967d547ce4313 1270 6792901f9f88e637 1271 493daaf401c92c27 1272 9dd10f0edb1c56f8 1273 080211f8480ee306 ) 1274 example. 86400 IN ZONEMD 2018031900 1 240 ( 1275 e2d523f654b9422a 1276 96c5a8f44607bbee ) 1277 example. 86400 IN ZONEMD 2018031900 241 1 ( 1278 e1846540e33a9e41 1279 89792d18d5d131f6 1280 05fc283e ) 1281 ns1.example. 3600 IN A 203.0.113.63 1282 ns2.example. 86400 IN TXT "This example has multiple digests" 1283 ns2.example. 3600 IN AAAA 2001:db8::63 1285 A.4. The URI.ARPA Zone 1287 The URI.ARPA zone retrieved 2018-10-21. Note this sample zone has 1288 (expired) signatures, but no signature for the ZONEMD RR. 1290 ; <<>> DiG 9.9.4 <<>> @lax.xfr.dns.icann.org uri.arpa axfr 1291 ; (2 servers found) 1292 ;; global options: +cmd 1293 uri.arpa. 3600 IN SOA sns.dns.icann.org. ( 1294 noc.dns.icann.org. 2018100702 10800 3600 1209600 3600 ) 1295 uri.arpa. 3600 IN RRSIG NSEC 8 2 3600 ( 1296 20181028142623 20181007205525 47155 uri.arpa. 1297 eEC4w/oXLR1Epwgv4MBiDtSBsXhqrJVvJWUpbX8XpetAvD35bxwNCUTi 1298 /pAJVUXefegWeiriD2rkTgCBCMmn7YQIm3gdR+HjY/+o3BXNQnz97f+e 1299 HAE9EDDzoNVfL1PyV/2fde9tDeUuAGVVwmD399NGq9jWYMRpyri2kysr q/g= ) 1300 uri.arpa. 86400 IN RRSIG NS 8 2 86400 ( 1301 20181028172020 20181007175821 47155 uri.arpa. 1302 ATyV2A2A8ZoggC+68u4GuP5MOUuR+2rr3eWOkEU55zAHld/7FiBxl4ln 1303 4byJYy7NudUwlMOEXajqFZE7DVl8PpcvrP3HeeGaVzKqaWj+aus0jbKF 1304 Bsvs2b1qDZemBfkz/IfAhUTJKnto0vSUicJKfItu0GjyYNJCz2CqEuGD Wxc= ) 1305 uri.arpa. 600 IN RRSIG MX 8 2 600 ( 1306 20181028170556 20181007175821 47155 uri.arpa. 1307 e7/r3KXDohX1lyVavetFFObp8fB8aXT76HnN9KCQDxSnSghNM83UQV0t 1308 lTtD8JVeN1mCvcNFZpagwIgB7XhTtm6Beur/m5ES+4uSnVeS6Q66HBZK 1309 A3mR95IpevuVIZvvJ+GcCAQpBo6KRODYvJ/c/ZG6sfYWkZ7qg/Em5/+3 4UI= ) 1310 uri.arpa. 3600 IN RRSIG DNSKEY 8 2 3600 ( 1311 20181028152832 20181007175821 15796 uri.arpa. 1312 nzpbnh0OqsgBBP8St28pLvPEQ3wZAUdEBuUwil+rtjjWlYYiqjPxZ286 1313 XF4Rq1usfV5x71jZz5IqswOaQgia91ylodFpLuXD6FTGs2nXGhNKkg1V 1314 chHgtwj70mXU72GefVgo8TxrFYzxuEFP5ZTP92t97FVWVVyyFd86sbbR 1315 6DZj3uA2wEvqBVLECgJLrMQ9Yy7MueJl3UA4h4E6zO2JY9Yp0W9woq0B 1316 dqkkwYTwzogyYffPmGAJG91RJ2h6cHtFjEZe2MnaY2glqniZ0WT9vXXd 1317 uFPm0KD9U77Ac+ZtctAF9tsZwSdAoL365E2L1usZbA+K0BnPPqGFJRJk 1318 5R0A1w== ) 1319 uri.arpa. 3600 IN RRSIG DNSKEY 8 2 3600 ( 1320 20181028152832 20181007175821 55480 uri.arpa. 1321 lWtQV/5szQjkXmbcD47/+rOW8kJPksRFHlzxxmzt906+DBYyfrH6uq5X 1322 nHvrUlQO6M12uhqDeL+bDFVgqSpNy+42/OaZvaK3J8EzPZVBHPJykKMV 1323 63T83aAiJrAyHzOaEdmzLCpalqcEE2ImzlLHSafManRfJL8Yuv+JDZFj 1324 2WDWfEcUuwkmIZWX11zxp+DxwzyUlRl7x4+ok5iKZWIg5UnBAf6B8T75 1325 WnXzlhCw3F2pXI0a5LYg71L3Tp/xhjN6Yy9jGlIRf5BjB59X2zra3a2R 1326 PkI09SSnuEwHyF1mDaV5BmQrLGRnCjvwXA7ho2m+vv4SP5dUdXf+GTeA 1327 1HeBfw== ) 1328 uri.arpa. 3600 IN RRSIG SOA 8 2 3600 ( 1329 20181029114753 20181008222815 47155 uri.arpa. 1330 qn8yBNoHDjGdT79U2Wu9IIahoS0YPOgYP8lG+qwPcrZ1BwGiHywuoUa2 1331 Mx6BWZlg+HDyaxj2iOmox+IIqoUHhXUbO7IUkJFlgrOKCgAR2twDHrXu 1332 9BUQHy9SoV16wYm3kBTEPyxW5FFm8vcdnKAF7sxSY8BbaYNpRIEjDx4A JUc= ) 1333 uri.arpa. 3600 IN NSEC ftp.uri.arpa. NS SOA ( 1334 MX RRSIG NSEC DNSKEY ) 1335 uri.arpa. 86400 IN NS a.iana-servers.net. 1336 uri.arpa. 86400 IN NS b.iana-servers.net. 1337 uri.arpa. 86400 IN NS c.iana-servers.net. 1338 uri.arpa. 86400 IN NS ns2.lacnic.net. 1339 uri.arpa. 86400 IN NS sec3.apnic.net. 1340 uri.arpa. 600 IN MX 10 pechora.icann.org. 1341 uri.arpa. 3600 IN DNSKEY 256 3 8 ( 1342 AwEAAcBi7tSart2J599zbYWspMNGN70IBWb4ziqyQYH9MTB/VCz6WyUK 1343 uXunwiJJbbQ3bcLqTLWEw134B6cTMHrZpjTAb5WAwg4XcWUu8mdcPTiL 1344 Bl6qVRlRD0WiFCTzuYUfkwsh1Rbr7rvrxSQhF5rh71zSpwV5jjjp65Wx 1345 SdJjlH0B ) 1346 uri.arpa. 3600 IN DNSKEY 257 3 8 ( 1347 AwEAAbNVv6ulgRdO31MtAehz7j3ALRjwZglWesnzvllQl/+hBRZr9QoY 1348 cO2I+DkO4Q1NKxox4DUIxj8SxPO3GwDuOFR9q2/CFi2O0mZjafbdYtWc 1349 3zSdBbi3q0cwCIx7GuG9eqlL+pg7mdk9dgdNZfHwB0LnqTD8ebLPsrO/ 1350 Id7kBaiqYOfMlZnh2fp+2h6OOJZHtY0DK1UlssyB5PKsE0tVzo5s6zo9 1351 iXKe5u+8WTMaGDY49vG80JPAKE7ezMiH/NZcUMiE0PRZ8D3foq2dYuS5 1352 ym+vA83Z7v8A+Rwh4UGnjxKB8zmr803V0ASAmHz/gwH5Vb0nH+LObwFt 1353 l3wpbp+Wpm8= ) 1354 uri.arpa. 3600 IN DNSKEY 257 3 8 ( 1355 AwEAAbwnFTakCvaUKsXji4mgmxZUJi1IygbnGahbkmFEa0L16J+TchKR 1356 wcgzVfsxUGa2MmeA4hgkAooC3uy+tTmoMsgy8uq/JAj24DjiHzd46LfD 1357 FK/qMidVqFpYSHeq2Vv5ojkuIsx4oe4KsafGWYNOczKZgH5loGjN2aJG 1358 mrIm++XCphOskgCsQYl65MIzuXffzJyxlAuts+ecAIiVeqRaqQfr8LRU 1359 7wIsLxinXirprtQrbor+EtvlHp9qXE6ARTZDzf4jvsNpKvLFZtmxzFf3 1360 e/UJz5eHjpwDSiZL7xE8aE1o1nGfPtJx9ZnB3bapltaJ5wY+5XOCKgY0 1361 xmJVvNQlwdE= ) 1362 ftp.uri.arpa. 3600 IN RRSIG NSEC 8 3 3600 ( 1363 20181028080856 20181007175821 47155 uri.arpa. 1364 HClGAqPxzkYkAT7Q/QNtQeB6YrkP6EPOef+9Qo5/2zngwAewXEAQiyF9 1365 jD1USJiroM11QqBS3v3aIdW/LXORs4Ez3hLcKNO1cKHsOuWAqzmE+BPP 1366 Arfh8N95jqh/q6vpaB9UtMkQ53tM2fYU1GszOLN0knxbHgDHAh2axMGH lqM= ) 1367 ftp.uri.arpa. 604800 IN RRSIG NAPTR 8 3 604800 ( 1368 20181028103644 20181007205525 47155 uri.arpa. 1369 WoLi+vZzkxaoLr2IGZnwkRvcDf6KxiWQd1WZP/U+AWnV+7MiqsWPZaf0 1370 9toRErerGoFOiOASNxZjBGJrRgjmavOM9U+LZSconP9zrNFd4dIu6kp5 1371 YxlQJ0uHOvx1ZHFCj6lAt1ACUIw04ZhMydTmi27c8MzEOMepvn7iH7r7 k7k= ) 1372 ftp.uri.arpa. 3600 IN NSEC http.uri.arpa. NAPTR ( 1373 RRSIG NSEC ) 1374 ftp.uri.arpa. 604800 IN NAPTR 0 0 "" "" ( 1375 "!^ftp://([^:/?#]*).*$!\\1!i" . ) 1376 http.uri.arpa. 3600 IN RRSIG NSEC 8 3 3600 ( 1377 20181029010647 20181007175821 47155 uri.arpa. 1378 U03NntQ73LHWpfLmUK8nMsqkwVsOGW2KdsyuHYAjqQSZvKbtmbv7HBmE 1379 H1+Ii3Z+wtfdMZBy5aC/6sHdx69BfZJs16xumycMlAy6325DKTQbIMN+ 1380 ift9GrKBC7cgCd2msF/uzSrYxxg4MJQzBPvlkwXnY3b7eJSlIXisBIn7 3b8= ) 1381 http.uri.arpa. 604800 IN RRSIG NAPTR 8 3 604800 ( 1382 20181029011815 20181007205525 47155 uri.arpa. 1383 T7mRrdag+WSmG+n22mtBSQ/0Y3v+rdDnfQV90LN5Fq32N5K2iYFajF7F 1384 Tp56oOznytfcL4fHrqOE0wRc9NWOCCUec9C7Wa1gJQcllEvgoAM+L6f0 1385 RsEjWq6+9jvlLKMXQv0xQuMX17338uoD/xiAFQSnDbiQKxwWMqVAimv5 7Zs= ) 1386 http.uri.arpa. 3600 IN NSEC mailto.uri.arpa. NAPTR ( 1387 RRSIG NSEC ) 1388 http.uri.arpa. 604800 IN NAPTR 0 0 "" "" ( 1389 "!^http://([^:/?#]*).*$!\\1!i" . ) 1390 mailto.uri.arpa. 3600 IN RRSIG NSEC 8 3 3600 ( 1391 20181028110727 20181007175821 47155 uri.arpa. 1392 GvxzVL85rEukwGqtuLxek9ipwjBMfTOFIEyJ7afC8HxVMs6mfFa/nEM/ 1393 IdFvvFg+lcYoJSQYuSAVYFl3xPbgrxVSLK125QutCFMdC/YjuZEnq5cl 1394 fQciMRD7R3+znZfm8d8u/snLV9w4D+lTBZrJJUBe1Efc8vum5vvV7819 ZoY= ) 1395 mailto.uri.arpa. 604800 IN RRSIG NAPTR 8 3 604800 ( 1396 20181028141825 20181007205525 47155 uri.arpa. 1397 MaADUgc3fc5v++M0YmqjGk3jBdfIA5RuP62hUSlPsFZO4k37erjIGCfF 1398 j+g84yc+QgbSde0PQHszl9fE/+SU5ZXiS9YdcbzSZxp2erFpZOTchrpg 1399 916T4vx6i59scodjb0l6bDyZ+mtIPrc1w6b4hUyOUTsDQoAJYxdfEuMg Vy4= ) 1400 mailto.uri.arpa. 3600 IN NSEC urn.uri.arpa. NAPTR ( 1401 RRSIG NSEC ) 1402 mailto.uri.arpa. 604800 IN NAPTR 0 0 "" "" ( 1403 "!^mailto:(.*)@(.*)$!\\2!i" . ) 1404 urn.uri.arpa. 3600 IN RRSIG NSEC 8 3 3600 ( 1405 20181028123243 20181007175821 47155 uri.arpa. 1406 Hgsw4Deops1O8uWyELGe6hpR/OEqCnTHvahlwiQkHhO5CSEQrbhmFAWe 1407 UOkmGAdTEYrSz+skLRQuITRMwzyFf4oUkZihGyhZyzHbcxWfuDc/Pd/9 1408 DSl56gdeBwy1evn5wBTms8yWQVkNtphbJH395gRqZuaJs3LD/qTyJ5Dp LvA= ) 1409 urn.uri.arpa. 604800 IN RRSIG NAPTR 8 3 604800 ( 1410 20181029071816 20181007205525 47155 uri.arpa. 1411 ALIZD0vBqAQQt40GQ0Efaj8OCyE9xSRJRdyvyn/H/wZVXFRFKrQYrLAS 1412 D/K7q6CMTOxTRCu2J8yes63WJiaJEdnh+dscXzZkmOg4n5PsgZbkvUSW 1413 BiGtxvz5jNncM0xVbkjbtByrvJQAO1cU1mnlDKe1FmVB1uLpVdA9Ib4J hMU= ) 1414 urn.uri.arpa. 3600 IN NSEC uri.arpa. NAPTR RRSIG ( 1415 NSEC ) 1416 urn.uri.arpa. 604800 IN NAPTR 0 0 "" "" ( 1417 "/urn:([^:]+)/\\1/i" . ) 1418 uri.arpa. 3600 IN SOA sns.dns.icann.org. ( 1419 noc.dns.icann.org. 2018100702 10800 3600 1209600 3600 ) 1420 ;; Query time: 66 msec 1421 ;; SERVER: 192.0.32.132#53(192.0.32.132) 1422 ;; WHEN: Sun Oct 21 20:39:28 UTC 2018 1423 ;; XFR size: 34 records (messages 1, bytes 3941) 1424 uri.arpa. 3600 IN ZONEMD 2018100702 1 1 ( 1425 1291b78ddf7669b1a39d014d87626b709b55774c5d7d58fa 1426 dc556439889a10eaf6f11d615900a4f996bd46279514e473 ) 1428 A.5. The ROOT-SERVERS.NET Zone 1430 The ROOT-SERVERS.NET zone retreived 2018-10-21. 1432 root-servers.net. 3600000 IN SOA a.root-servers.net. ( 1433 nstld.verisign-grs.com. 2018091100 14400 7200 1209600 3600000 ) 1434 root-servers.net. 3600000 IN NS a.root-servers.net. 1435 root-servers.net. 3600000 IN NS b.root-servers.net. 1436 root-servers.net. 3600000 IN NS c.root-servers.net. 1437 root-servers.net. 3600000 IN NS d.root-servers.net. 1438 root-servers.net. 3600000 IN NS e.root-servers.net. 1439 root-servers.net. 3600000 IN NS f.root-servers.net. 1440 root-servers.net. 3600000 IN NS g.root-servers.net. 1441 root-servers.net. 3600000 IN NS h.root-servers.net. 1442 root-servers.net. 3600000 IN NS i.root-servers.net. 1443 root-servers.net. 3600000 IN NS j.root-servers.net. 1444 root-servers.net. 3600000 IN NS k.root-servers.net. 1445 root-servers.net. 3600000 IN NS l.root-servers.net. 1446 root-servers.net. 3600000 IN NS m.root-servers.net. 1447 a.root-servers.net. 3600000 IN AAAA 2001:503:ba3e::2:30 1448 a.root-servers.net. 3600000 IN A 198.41.0.4 1449 b.root-servers.net. 3600000 IN MX 20 mail.isi.edu. 1450 b.root-servers.net. 3600000 IN AAAA 2001:500:200::b 1451 b.root-servers.net. 3600000 IN A 199.9.14.201 1452 c.root-servers.net. 3600000 IN AAAA 2001:500:2::c 1453 c.root-servers.net. 3600000 IN A 192.33.4.12 1454 d.root-servers.net. 3600000 IN AAAA 2001:500:2d::d 1455 d.root-servers.net. 3600000 IN A 199.7.91.13 1456 e.root-servers.net. 3600000 IN AAAA 2001:500:a8::e 1457 e.root-servers.net. 3600000 IN A 192.203.230.10 1458 f.root-servers.net. 3600000 IN AAAA 2001:500:2f::f 1459 f.root-servers.net. 3600000 IN A 192.5.5.241 1460 g.root-servers.net. 3600000 IN AAAA 2001:500:12::d0d 1461 g.root-servers.net. 3600000 IN A 192.112.36.4 1462 h.root-servers.net. 3600000 IN AAAA 2001:500:1::53 1463 h.root-servers.net. 3600000 IN A 198.97.190.53 1464 i.root-servers.net. 3600000 IN MX 10 mx.i.root-servers.org. 1465 i.root-servers.net. 3600000 IN AAAA 2001:7fe::53 1466 i.root-servers.net. 3600000 IN A 192.36.148.17 1467 j.root-servers.net. 3600000 IN AAAA 2001:503:c27::2:30 1468 j.root-servers.net. 3600000 IN A 192.58.128.30 1469 k.root-servers.net. 3600000 IN AAAA 2001:7fd::1 1470 k.root-servers.net. 3600000 IN A 193.0.14.129 1471 l.root-servers.net. 3600000 IN AAAA 2001:500:9f::42 1472 l.root-servers.net. 3600000 IN A 199.7.83.42 1473 m.root-servers.net. 3600000 IN AAAA 2001:dc3::35 1474 m.root-servers.net. 3600000 IN A 202.12.27.33 1475 root-servers.net. 3600000 IN SOA a.root-servers.net. ( 1476 nstld.verisign-grs.com. 2018091100 14400 7200 1209600 3600000 ) 1477 root-servers.net. 3600000 IN ZONEMD 2018091100 1 1 ( 1478 f1ca0ccd91bd5573d9f431c00ee0101b2545c97602be0a97 1479 8a3b11dbfc1c776d5b3e86ae3d973d6b5349ba7f04340f79 ) 1481 Authors' Addresses 1483 Duane Wessels 1484 Verisign 1485 12061 Bluemont Way 1486 Reston, VA 20190 1488 Phone: +1 703 948-3200 1489 Email: dwessels@verisign.com 1490 URI: http://verisign.com 1492 Piet Barber 1493 Verisign 1494 12061 Bluemont Way 1495 Reston, VA 20190 1497 Phone: +1 703 948-3200 1498 Email: pbarber@verisign.com 1499 URI: http://verisign.com 1501 Matt Weinberg 1502 Verisign 1503 12061 Bluemont Way 1504 Reston, VA 20190 1506 Phone: +1 703 948-3200 1507 Email: mweinberg@verisign.com 1508 URI: http://verisign.com 1510 Warren Kumari 1511 Google 1512 1600 Amphitheatre Parkway 1513 Mountain View, CA 94043 1515 Email: warren@kumari.net 1517 Wes Hardaker 1518 USC/ISI 1519 P.O. Box 382 1520 Davis, CA 95617 1522 Email: ietf@hardakers.net