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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 Verisign 5 Expires: December 14, 2020 M. Weinberg 6 Amazon 7 W. Kumari 8 Google 9 W. Hardaker 10 USC/ISI 11 June 12, 2020 13 Message Digest for DNS Zones 14 draft-ietf-dnsop-dns-zone-digest-08 16 Abstract 18 This document describes a protocol and new DNS Resource Record that 19 can be used to provide a cryptographic message digest over DNS zone 20 data. The ZONEMD Resource Record conveys the digest data in the zone 21 itself. When a zone publisher includes an ZONEMD record, recipients 22 can verify the zone contents for accuracy and completeness. This 23 provides assurance that received zone data matches published data, 24 regardless of how the zone data has been transmitted and received. 26 ZONEMD is not designed to replace DNSSEC. Whereas DNSSEC protects 27 individual RRSets (DNS data with fine granularity), ZONEMD protects a 28 zone's data as a whole, whether consumed by authoritative name 29 servers, recursive name servers, or any other applications. 31 As specified at this time, ZONEMD is not designed for use in large, 32 dynamic zones due to the time and resources required for digest 33 calculation. The ZONEMD record described in this document is 34 designed so that new digest schemes may be developed in the future to 35 support large, dynamic zones. 37 Status of This Memo 39 This Internet-Draft is submitted in full conformance with the 40 provisions of BCP 78 and BCP 79. 42 Internet-Drafts are working documents of the Internet Engineering 43 Task Force (IETF). Note that other groups may also distribute 44 working documents as Internet-Drafts. The list of current Internet- 45 Drafts is at https://datatracker.ietf.org/drafts/current/. 47 Internet-Drafts are draft documents valid for a maximum of six months 48 and may be updated, replaced, or obsoleted by other documents at any 49 time. It is inappropriate to use Internet-Drafts as reference 50 material or to cite them other than as "work in progress." 52 This Internet-Draft will expire on December 14, 2020. 54 Copyright Notice 56 Copyright (c) 2020 IETF Trust and the persons identified as the 57 document authors. All rights reserved. 59 This document is subject to BCP 78 and the IETF Trust's Legal 60 Provisions Relating to IETF Documents 61 (https://trustee.ietf.org/license-info) in effect on the date of 62 publication of this document. Please review these documents 63 carefully, as they describe your rights and restrictions with respect 64 to this document. Code Components extracted from this document must 65 include Simplified BSD License text as described in Section 4.e of 66 the Trust Legal Provisions and are provided without warranty as 67 described in the Simplified BSD License. 69 Table of Contents 71 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 3 72 1.1. Motivation . . . . . . . . . . . . . . . . . . . . . . . 4 73 1.2. Design Overview . . . . . . . . . . . . . . . . . . . . . 6 74 1.3. Use Cases . . . . . . . . . . . . . . . . . . . . . . . . 6 75 1.3.1. Root Zone . . . . . . . . . . . . . . . . . . . . . . 6 76 1.3.2. Providers, Secondaries, and Anycast . . . . . . . . . 6 77 1.3.3. Response Policy Zones . . . . . . . . . . . . . . . . 7 78 1.3.4. Centralized Zone Data Service . . . . . . . . . . . . 7 79 1.3.5. General Purpose Comparison Check . . . . . . . . . . 7 80 1.4. Requirements Language . . . . . . . . . . . . . . . . . . 7 81 2. The ZONEMD Resource Record . . . . . . . . . . . . . . . . . 7 82 2.1. Non-apex ZONEMD Records . . . . . . . . . . . . . . . . . 8 83 2.2. ZONEMD RDATA Wire Format . . . . . . . . . . . . . . . . 8 84 2.2.1. The Serial Field . . . . . . . . . . . . . . . . . . 8 85 2.2.2. The Scheme Field . . . . . . . . . . . . . . . . . . 9 86 2.2.3. The Hash Algorithm Field . . . . . . . . . . . . . . 9 87 2.2.4. The Digest Field . . . . . . . . . . . . . . . . . . 9 88 2.3. ZONEMD Presentation Format . . . . . . . . . . . . . . . 9 89 2.4. ZONEMD Example . . . . . . . . . . . . . . . . . . . . . 10 90 3. Calculating the Digest . . . . . . . . . . . . . . . . . . . 10 91 3.1. Add ZONEMD Placeholder . . . . . . . . . . . . . . . . . 10 92 3.2. Optionally Sign the Zone . . . . . . . . . . . . . . . . 10 93 3.3. Canonical Format and Ordering . . . . . . . . . . . . . . 11 94 3.4. Inclusion/Exclusion Rules . . . . . . . . . . . . . . . . 11 95 3.5. Scheme-Specific Processing . . . . . . . . . . . . . . . 12 96 3.5.1. The SIMPLE Scheme . . . . . . . . . . . . . . . . . . 12 98 3.6. Update ZONEMD RR . . . . . . . . . . . . . . . . . . . . 12 99 4. Verifying Zone Digest . . . . . . . . . . . . . . . . . . . . 12 100 5. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 14 101 5.1. ZONEMD RRtype . . . . . . . . . . . . . . . . . . . . . . 14 102 5.2. ZONEMD Scheme . . . . . . . . . . . . . . . . . . . . . . 14 103 5.3. ZONEMD Hash Algorithm . . . . . . . . . . . . . . . . . . 14 104 6. Security Considerations . . . . . . . . . . . . . . . . . . . 15 105 6.1. Attacks Against the Zone Digest . . . . . . . . . . . . . 15 106 6.2. Attacks Utilizing ZONEMD Queries . . . . . . . . . . . . 15 107 6.3. Resilience and Fragility . . . . . . . . . . . . . . . . 16 108 7. Performance Considerations . . . . . . . . . . . . . . . . . 16 109 7.1. SIMPLE SHA384 . . . . . . . . . . . . . . . . . . . . . . 16 110 8. Privacy Considerations . . . . . . . . . . . . . . . . . . . 17 111 9. Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . 17 112 10. Implementation Status . . . . . . . . . . . . . . . . . . . . 17 113 10.1. Authors' Implementation . . . . . . . . . . . . . . . . 17 114 10.2. Shane Kerr's Implementation . . . . . . . . . . . . . . 18 115 10.3. NIC Chile Labs Implementation . . . . . . . . . . . . . 18 116 11. Change Log . . . . . . . . . . . . . . . . . . . . . . . . . 19 117 12. References . . . . . . . . . . . . . . . . . . . . . . . . . 24 118 12.1. Normative References . . . . . . . . . . . . . . . . . . 24 119 12.2. Informative References . . . . . . . . . . . . . . . . . 24 120 Appendix A. Example Zones With Digests . . . . . . . . . . . . . 26 121 A.1. Simple EXAMPLE Zone . . . . . . . . . . . . . . . . . . . 27 122 A.2. Complex EXAMPLE Zone . . . . . . . . . . . . . . . . . . 27 123 A.3. EXAMPLE Zone with multiple digests . . . . . . . . . . . 28 124 A.4. The URI.ARPA Zone . . . . . . . . . . . . . . . . . . . . 29 125 A.5. The ROOT-SERVERS.NET Zone . . . . . . . . . . . . . . . . 32 126 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 34 128 1. Introduction 130 In the DNS, a zone is the collection of authoritative resource 131 records (RRs) sharing a common origin ([RFC8499]). Zones are often 132 stored as files on disk in the so-called master file format 133 [RFC1034]. Zones are generally distributed among name servers using 134 the AXFR [RFC5936], and IXFR [RFC1995] protocols. Zone files can 135 also be distributed outside of the DNS, with such protocols as FTP, 136 HTTP, rsync, and even via email. Currently there is no standard way 137 to verify the authenticity of a stand-alone zone. 139 This document introduces a new RR type that serves as a cryptographic 140 message digest of the data in a zone. It allows a receiver of the 141 zone to verify the zone's authenticity, especially when used in 142 combination with DNSSEC. This technique makes the digest a part of 143 the zone itself, allowing verification the zone as a whole, no matter 144 how it is transmitted. Furthermore, the digest is based on the wire 145 format of zone data. Thus, it is independent of presentation format, 146 such as changes in whitespace, capitalization, and comments. 148 DNSSEC provides three strong security guarantees relevant to this 149 protocol: 151 1. whether or not to expect DNSSEC records in the zone, 153 2. whether or not to expect a ZONEMD record in a signed zone, and 155 3. whether or not the ZONEMD record has been altered since it was 156 signed. 158 This specification is OPTIONAL to implement by both publishers and 159 consumers of zone data. 161 1.1. Motivation 163 The motivation for this protocol enhancement is the desire for the 164 ability to verify the authenticity of a stand-alone zone, regardless 165 of how it is transmitted. A consumer of zone data should be able to 166 verify that the data is as-published by the zone operator. 168 One approach to preventing data tampering and corruption is to secure 169 the distribution channel. The DNS has a number of features that can 170 already be used for channel security. Perhaps the most widely used 171 is DNS transaction signatures (TSIG [RFC2845]). TSIG uses shared 172 secret keys and a message digest to protect individual query and 173 response messages. It is generally used to authenticate and validate 174 UPDATE [RFC2136], AXFR [RFC5936], and IXFR [RFC1995] messages. 176 DNS Request and Transaction Signatures (SIG(0) [RFC2931]) is another 177 protocol extension designed to authenticate individual DNS 178 transactions. Whereas SIG records were originally designed to cover 179 specific RR types, SIG(0) is used to sign an entire DNS message. 180 Unlike TSIG, SIG(0) uses public key cryptography rather than shared 181 secrets. 183 The Transport Layer Security protocol suite is also designed to 184 provide channel security. One can easily imagine the distribution of 185 zones over HTTPS-enabled web servers, as well as DNS-over-HTTPS 186 [RFC8484], and perhaps even a future version of DNS-over-TLS 187 ([RFC7858]). 189 Unfortunately, the protections provided by these channel security 190 techniques are (in practice) ephemeral and are not retained after the 191 data transfer is complete. They can ensure that the client receives 192 the data from the expected server, and that the data sent by the 193 server is not modified during transmission. However, they do not 194 guarantee that the server transmits the data as originally published, 195 and do not provide any methods to verify data that is read after 196 transmission is complete. For example, a name server loading saved 197 zone data upon restart cannot guarantee that the on-disk data has not 198 been modified. For these reasons, it is preferable to secure the 199 data itself. 201 Why not simply rely on DNSSEC, which provides certain data security 202 guarantees? Certainly for zones that are signed, a recipient could 203 validate all of the signed RRSets. Additionally, denial-of-existence 204 records can prove that RRSets have not been added or removed. 205 However, not all RRSets in a zone are signed. The design of DNSSEC 206 stipulates that delegations (non-apex NS records) are not signed, and 207 neither are any glue records. ZONEMD protects the integrity of 208 delegation, glue, and other records that are not otherwise covered by 209 DNSSEC. Furthermore, zones that employ NSEC3 with opt-out are 210 susceptible to the removal or addition of names between the signed 211 nodes. Whereas DNSSEC is primarily designed to protect consumers of 212 DNS response messages, this protocol is designed to protect consumers 213 of zones. 215 There are existing tools and protocols that provide data security, 216 such as OpenPGP [RFC4880] and S/MIME [RFC5751]. In fact, the 217 internic.net site publishes PGP signatures along side the root zone 218 and other files available there. However, this is a detached 219 signature with no strong association to the corresponding zone file 220 other than its timestamp. Non-detached signatures are, of course, 221 possible, but these necessarily change the format of the file being 222 distributed. That is, a zone signed with OpenPGP or S/MIME no longer 223 looks like a DNS zone and could not directly be loaded into a name 224 server. Once loaded the signature data is lost, so it does not 225 survive further propagation. 227 It seems the desire for data security in DNS zones was envisioned as 228 far back as 1997. [RFC2065] is an obsoleted specification of the 229 first generation DNSSEC Security Extensions. It describes a zone 230 transfer signature, aka AXFR SIG, which is similar to the technique 231 proposed by this document. That is, it proposes ordering all 232 (signed) RRSets in a zone, hashing their contents, and then signing 233 the zone hash. The AXFR SIG is described only for use during zone 234 transfers. It did not postulate the need to validate zone data 235 distributed outside of the DNS. Furthermore, its successor, 236 [RFC2535], omits the AXFR SIG, while at the same time introducing an 237 IXFR SIG. 239 1.2. Design Overview 241 This document introduces a new Resource Record type designed to 242 convey a message digest of the content of a zone. The digest is 243 calculated at the time of zone publication. Ideally the zone is 244 signed with DNSSEC to guarantee that any modifications of the digest 245 can be detected. The procedures for digest calculation and DNSSEC 246 signing are similar. Both require data to be processed in a well- 247 defined order and format. In some cases it may be possible to 248 perform DNSSEC signing and digest calculation in parallel. 250 The zone digest is designed to be used on zones that are relatively 251 stable and have infrequent updates. As currently specified, the 252 digest is re-calculated over the entire zone content each time. This 253 specification does not provide an efficient mechanism for incremental 254 updates of zone data. It is, however, extensible so that future 255 schemes to support incremental zone digest algorithms (e.g. using 256 Merkle trees) can be accommodated. 258 It is expected that verification of a zone digest would be 259 implemented in name server software. That is, a name server can 260 verify the zone data it was given and refuse to serve a zone which 261 fails verification. For signed zones, the name server needs a trust 262 anchor to perform DNSSEC validation. For signed non-root zones, the 263 name server may need to send queries to validate a chain-of-trust. 264 Digest verification could also be performed externally. 266 1.3. Use Cases 268 1.3.1. Root Zone 270 The root zone [InterNIC] is one of the most widely distributed DNS 271 zone on the Internet, served by more than 1000 separate instances 272 [RootServers] at the time of this writing. Additionally, many 273 organizations configure their own name servers to serve the root zone 274 locally. Reasons for doing so include privacy and reduced access 275 time. [RFC7706] describes one, but not the only, way to do this. As 276 the root zone spreads beyond its traditional deployment boundaries, 277 the need for verification of the completeness of the zone contents 278 becomes increasingly important. 280 1.3.2. Providers, Secondaries, and Anycast 282 Since its very early days, the developers of the DNS recognized the 283 importance of secondary name servers and service diversity. However, 284 they may not have anticipated the complexity of modern DNS service 285 provisioning which can include multiple third-party providers and 286 hundreds of anycast instances. Instead of a simple primary-to- 287 secondary zone distribution system, today it is possible to have 288 multiple levels, multiple parties, and multiple protocols involved in 289 the distribution of zone data. This complexity introduces new places 290 for problems to arise. The zone digest protects the integrity of 291 data that flows through such systems. 293 1.3.3. Response Policy Zones 295 DNS Response Policy Zones is "a method of expressing DNS response 296 policy information inside specially constructed DNS zones..." [RPZ]. 297 A number of companies provide RPZ feeds, which can be consumed by 298 name server and firewall products. Since these are zones, AXFR is 299 often, but not necessarily used for transmission. While RPZ zones 300 can certainly be signed with DNSSEC, the data is not queried 301 directly, and would not be subject to DNSSEC validation. 303 1.3.4. Centralized Zone Data Service 305 ICANN operates the Centralized Zone Data Service [CZDS], which is a 306 repository of top-level domain zone files. Users request access to 307 the system, and to individual zones, and are then able to download 308 zone data for certain uses. Adding a zone digest to these would 309 provide CZDS users with assurances that the data has not been 310 modified. Note that ZONEMD could be added to CZDS zone data 311 independently of the zone served by production name servers. 313 1.3.5. General Purpose Comparison Check 315 Since the zone digest calculation does not depend on presentation 316 format, it could be used to compare multiple copies of a zone 317 received from different sources, or copies generated by different 318 processes. 320 1.4. Requirements Language 322 The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", 323 "SHOULD", "SHOULD NOT", "RECOMMENDED", "NOT RECOMMENDED", "MAY", and 324 "OPTIONAL" in this document are to be interpreted as described in BCP 325 14 [RFC2119] [RFC8174] when, and only when, they appear in all 326 capitals, as shown here. 328 2. The ZONEMD Resource Record 330 This section describes the ZONEMD Resource Record, including its 331 fields, wire format, and presentation format. The Type value for the 332 ZONEMD RR is 63. The ZONEMD RR is class independent. The RDATA of 333 the resource record consists of four fields: Serial, Scheme, Hash 334 Algorithm, and Digest. 336 A zone MAY contain multiple ZONEMD RRs to support algorithm agility 337 [RFC7696] and rollovers. Each ZONEMD RR must specify a unique Scheme 338 and Hash Algorithm tuple. It is recommended that a zone include only 339 one ZONEMD RR, unless the zone publisher is in the process of 340 transitioning to a new Scheme or Hash Algorithm. 342 2.1. Non-apex ZONEMD Records 344 This specification utilizes ZONEMD RRs located at the zone apex. 345 Non-apex ZONEMD RRs are not forbidden, but have no meaning in this 346 specification. Non-apex ZONEMD RRs MUST NOT be used for 347 verification. 349 During digest calculation, non-apex ZONEMD RRs are treated like any 350 other RRs. They are digested as-is and the RR is not replaced by a 351 placeholder RR. 353 Unless explicitly stated otherwise, "ZONEMD" always refers to apex 354 records throughout this document. 356 2.2. ZONEMD RDATA Wire Format 358 The ZONEMD RDATA wire format is encoded as follows: 360 1 1 1 1 1 1 1 1 1 1 2 2 2 2 2 2 2 2 2 2 3 3 361 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 1 362 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 363 | Serial | 364 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 365 | Scheme |Hash Algorithm | | 366 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | 367 | Digest | 368 / / 369 / / 370 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 372 2.2.1. The Serial Field 374 The Serial field is a 32-bit unsigned integer in network order. It 375 is equal to the serial number from the zone's SOA record ([RFC1035] 376 section 3.3.13) for which the zone digest was generated. 378 The zone's serial number is included here in order to make DNS 379 response messages of type ZONEMD meaningful. Without the serial 380 number, a stand-alone ZONEMD digest has no association to any 381 particular instance of a zone. 383 2.2.2. The Scheme Field 385 The Scheme field is an 8-bit unsigned integer that identifies the 386 methods by which data is collated and presented as input to the 387 hashing function. 389 At the time of this writing, SIMPLE, with value 1, is the only 390 standardized Scheme defined for ZONEMD records. The Scheme registry 391 is further described in Section 5. 393 Scheme values 240-254 are allocated for Private Use as described in 394 [RFC8126]. 396 2.2.3. The Hash Algorithm Field 398 The Hash Algorithm field is an 8-bit unsigned integer that identifies 399 the cryptographic hash algorithm used to construct the digest. 401 At the time of this writing, SHA384, with value 1, is the only 402 standardized Hash Algorithm defined for ZONEMD records. The Hash 403 Algorithm registry is further described in Section 5. 405 Hash Algorithm values 240-254 are allocated for Private Use as 406 described in [RFC8126]. 408 2.2.4. The Digest Field 410 The Digest field is a variable-length sequence of octets containing 411 the output of the hash algorithm. The Digest field must not be 412 empty. Section 3 describes how to calculate the digest for a zone. 413 Section 4 describes how to use the digest to verify the contents of a 414 zone. 416 2.3. ZONEMD Presentation Format 418 The presentation format of the RDATA portion is as follows: 420 The Serial field is represented as an unsigned decimal integer. 422 The Scheme field is represented as an unsigned decimal integer. 424 The Hash Algorithm field is represented as an unsigned decimal 425 integer. 427 The Digest is represented as a sequence of case-insensitive 428 hexadecimal digits. Whitespace is allowed within the hexadecimal 429 text. 431 2.4. ZONEMD Example 433 The following example shows a ZONEMD RR. 435 example.com. 86400 IN ZONEMD 2018031500 1 1 ( 436 FEBE3D4CE2EC2FFA4BA99D46CD69D6D29711E55217057BEE 437 7EB1A7B641A47BA7FED2DD5B97AE499FAFA4F22C6BD647DE ) 439 3. Calculating the Digest 441 3.1. Add ZONEMD Placeholder 443 In preparation for calculating the zone digest, any existing ZONEMD 444 records (and covering RRSIGs) at the zone apex are first deleted. 446 Prior to calculation of the digest, and prior to signing with DNSSEC, 447 one or more placeholder ZONEMD records are added to the zone apex. 448 This ensures that denial-of-existence (NSEC, NSEC3) records are 449 created correctly if the zone is signed with DNSSEC. If placeholders 450 are not added prior to signing, the later addition of ZONEMD records 451 would also require updating the Type Bit Maps field of any apex NSEC/ 452 NSEC3 RRs, which then invalidates the calculated digest value. 454 When multiple ZONEMD RRs are published in the zone, e.g., during an 455 algorithm rollover, each must specify a unique Scheme and Hash 456 Algorithm tuple. 458 It is recommended that the TTL of the ZONEMD record match the TTL of 459 the SOA. 461 In the placeholder record, the Serial field is set to the current SOA 462 Serial. The Scheme field is set to the value for the chosen 463 collation scheme. The Hash Algorithm field is set to the value for 464 the chosen hash algorithm. Since ZONEMD records are excluded from 465 digest calculation, the value of the Digest field does not matter at 466 this point in the process. Implementations MAY want to set the 467 Digest field to all zeroes anyway. 469 3.2. Optionally Sign the Zone 471 Following addition of placeholder records, the zone may be signed 472 with DNSSEC. Note that when the digest calculation is complete, and 473 the ZONEMD record is updated, the signature(s) for the ZONEMD RRSet 474 MUST be recalculated and updated as well. Therefore, the signer is 475 not required to calculate a signature over the placeholder record at 476 this step in the process, but it is harmless to do so. 478 3.3. Canonical Format and Ordering 480 Calculation of a zone digest REQUIRES RRs to be processed in a 481 consistent format and ordering. Correct ordering depends on (1) 482 ordering of owner names, (2) ordering of RRSets with the same owner 483 name, and (3) ordering of RRs within an RRSet. 485 This specification adopts DNSSEC's canonical ordering for names 486 (Section 6.1 of [RFC4034]), and canonical ordering for RRs within an 487 RRSet (Section 6.3 of [RFC4034]). It also adopts DNSSEC's canonical 488 RR form (Section 6.2 of [RFC4034]). 490 However, since DNSSEC does not define a canonical ordering for RRSets 491 having the same owner name, that ordering is defined here. For the 492 purposes of calculating the zone digest, RRSets having the same owner 493 name MUST be numerically ordered, in ascending order, by their 494 numeric RR TYPE. 496 This specification adopts DNSSEC's canonical on-the-wire RR format 497 (without name compression) as specified in [RFC4034]: 499 RR(i) = owner | type | class | TTL | RDATA length | RDATA 501 where "|" denotes concatenation. 503 3.4. Inclusion/Exclusion Rules 505 When iterating over records in the zone, the following inclusion/ 506 exclusion rules apply: 508 o All records in the zone, including glue records, MUST be included. 510 o Occluded data ([RFC5936] Section 3.5) MUST be included. 512 o Only one instance of duplicate RRs with equal owner, class, type 513 and RDATA SHALL be included ([RFC4034] Section 6.3). 515 o The placeholder ZONEMD RR(s) MUST NOT be included. 517 o If the zone is signed, DNSSEC RRs MUST be included, except: 519 o The RRSIG covering ZONEMD MUST NOT be included because the RRSIG 520 will be updated after all digests have been calculated. 522 3.5. Scheme-Specific Processing 524 At this time, only the SIMPLE collation scheme is defined. 525 Additional schemes may be defined in future updates to this document. 527 3.5.1. The SIMPLE Scheme 529 For the SIMPLE scheme, the digest is calculated over the zone as a 530 whole. This means that a change to a single RR in the zone requires 531 iterating over all RRs in the zone to recalculate the digest. SIMPLE 532 is a good choice for zones that are small and/or stable, but probably 533 not good for zones that are large and/or dynamic. 535 A zone digest using the SIMPLE scheme is calculated by concatenating 536 the canonical form of all RRs in the zone, in the order described in 537 Section 3.3, subject to the inclusion/exclusion rules described in 538 Section 3.4, and then applying the SHA-384 algorithm: 540 digest = hash( RR(1) | RR(2) | RR(3) | ... ) 542 where "|" denotes concatenation. 544 3.6. Update ZONEMD RR 546 Once a zone digest has been calculated, the published ZONEMD record 547 is finalised by inserting the digest into the placeholder ZONEMD. 548 Repeat for each digest if multiple digests are to be published. 550 If the zone is signed with DNSSEC, the RRSIG record(s) covering the 551 ZONEMD RRSet MUST then be added or updated. Because the ZONEMD 552 placeholder was added prior to signing, the zone will already have 553 the appropriate denial-of-existence (NSEC, NSEC3) records. 555 Some DNSSEC implementations (especially "online signing") might be 556 designed such that the SOA serial number is updated whenever a new 557 signature is made. To preserve the calculated digest, generation of 558 an ZONEMD signature must not also result in a change to the SOA 559 serial number. The ZONEMD RR and the matching SOA MUST be published 560 at the same time. 562 4. Verifying Zone Digest 564 The recipient of a zone that has a ZONEMD RR can verify the zone by 565 calculating the digest as follows. If multiple ZONEMD RRs are 566 present in the zone, e.g., during an algorithm rollover, a match 567 using any one of the recipient's supported Schemes and Hash 568 Algorithms is sufficient to verify the zone. 570 1. The verifier MUST first determine whether or not to expect DNSSEC 571 records in the zone. This can be done by examining locally 572 configured trust anchors, or querying for (and validating) DS RRs 573 in the parent zone. For zones that are provably insecure, or if 574 DNSSEC validation can not be performed, digest validation 575 continues at step 4 below. 577 2. For zones that are provably secure, the existence of the apex 578 ZONEMD record MUST be verified. If the ZONEMD record provably 579 does not exist, digest verification cannot be done. If the 580 ZONEMD record does provably exist, but is not found in the zone, 581 digest verification MUST NOT be considered successful. 583 3. For zones that are provably secure, the SOA and ZONEMD RRSets 584 MUST have valid signatures, chaining up to a trust anchor. If 585 DNSSEC validation of the SOA or ZONEMD records fails, digest 586 verification MUST NOT be considered successful. 588 4. If the ZONEMD RRSet contains more than one RR with the same 589 Scheme and Hash Algorithm, digest verification MUST NOT be 590 considered successful. 592 5. Loop over all apex ZONEMD RRs and perform the following steps: 594 A. The SOA Serial field MUST exactly match the ZONEMD Serial 595 field. If the fields do not match, digest verification MUST 596 NOT be considered successful with this ZONEMD RR. 598 B. The Scheme field MUST be checked. If the verifier does not 599 support the given scheme, it SHOULD report that the RR's 600 digest could not be verified due to an unsupported scheme. 602 C. The Hash Algorithm field MUST be checked. If the verifier 603 does not support the given hash algorithm, it SHOULD report 604 that the RR's digest could not be verified due to an 605 unsupported algorithm. 607 D. The zone digest is computed over the zone data as described 608 in Section 3.5, using the Scheme and Hash Algorithm for the 609 current ZONEMD RR. 611 E. The computed digest is compared to the received digest. If 612 the two digest values match, verification is considered 613 successful. Otherwise, verification MUST NOT be considered 614 successful for this ZONEMD RR. 616 5. IANA Considerations 618 5.1. ZONEMD RRtype 620 This document defines a new DNS RR type, ZONEMD, whose value 63 has 621 been allocated by IANA from the "Resource Record (RR) TYPEs" 622 subregistry of the "Domain Name System (DNS) Parameters" registry: 624 Type: ZONEMD 626 Value: 63 628 Meaning: Message Digest Over Zone Data 630 Reference: This document 632 5.2. ZONEMD Scheme 634 This document asks IANA to create a new "ZONEMD Scheme" registry with 635 initial contents as follows: 637 +---------+--------------------+----------+-----------+-------------+ 638 | Value | Description | Mnemonic | Status | Reference | 639 +---------+--------------------+----------+-----------+-------------+ 640 | 0 | Reserved | RESERVED | N/A | N/A | 641 | 1 | Simple ZONEMD | SIMPLE | Mandatory | This | 642 | | collation | | | document | 643 | 240-254 | Private Use | N/A | N/A | [RFC8126] | 644 +---------+--------------------+----------+-----------+-------------+ 646 Table 1: ZONEMD Scheme Registry 648 The IANA policy for assigning new values to the ZONEMD Scheme 649 registry shall be Specification Required, as described in [RFC8126]. 651 5.3. ZONEMD Hash Algorithm 653 This document asks IANA to create a new "ZONEMD Hash Algorithm" 654 registry with initial contents as follows: 656 +---------+----------------------+----------+-----------+-----------+ 657 | Value | Description | Mnemonic | Status | Reference | 658 +---------+----------------------+----------+-----------+-----------+ 659 | 0 | Reserved | RESERVED | N/A | N/A | 660 | 1 | The SHA-384 hash | SHA384 | Mandatory | [RFC6234] | 661 | | algorithm | | | | 662 | 240-254 | Private Use | N/A | N/A | [RFC8126] | 663 +---------+----------------------+----------+-----------+-----------+ 665 Table 2: ZONEMD Hash Algorithm Registry 667 The IANA policy for assigning new values to the ZONEMD Hash Algorithm 668 registry shall be Specification Required, as described in [RFC8126]. 670 6. Security Considerations 672 6.1. Attacks Against the Zone Digest 674 The zone digest allows the receiver to verify that the zone contents 675 haven't been modified since the zone was generated/published. 676 Verification is strongest when the zone is also signed with DNSSEC. 677 An attacker, whose goal is to modify zone content before it is used 678 by the victim, may consider a number of different approaches. 680 The attacker might perform a downgrade attack to an unsigned zone. 681 This is why Section 4 talks about determining whether or not to 682 expect DNSSEC signatures for the zone in step 1. 684 The attacker might perform a downgrade attack by removing one or more 685 ZONEMD records. Such a removal is detectable only with DNSSEC 686 validation and is why Section 4 talks about checking denial-of- 687 existence proofs in step 2 and signature validation in step 3. 689 The attacker might alter the Scheme, Hash Algorithm, or Digest fields 690 of the ZONEMD record. Such modifications are detectable only with 691 DNSSEC validation. 693 6.2. Attacks Utilizing ZONEMD Queries 695 Nothing in this specification prevents clients from making, and 696 servers from responding to, ZONEMD queries. Servers SHOULD NOT 697 calculate zone digests dynamically (for each query) as this can be 698 used as a CPU resource exhaustion attack. 700 One might consider how well ZONEMD responses could be used in a 701 distributed denial-of-service amplification attack. The ZONEMD RR is 702 moderately sized, much like the DS RR. A single ZONEMD RR 703 contributes approximately 40 to 65 octets to a DNS response, for 704 currently defined digest types. Certainly other RR types result in 705 larger amplification effects (i.e., DNSKEY). 707 6.3. Resilience and Fragility 709 ZONEMD can be used to detect incomplete or corrupted zone data prior 710 to its use, thereby increasing resilience, but also introducing some 711 fragility. Publishers and consumers of zones containing ZONEMD 712 records should be aware of these tradeoffs. While the intention is 713 to secure the zone data, misconfigurations or implementation bugs are 714 generally indistinguishable from intentional tampering, and could 715 lead to service failures when verification is performed 716 automatically. 718 Zone publishers may want to deploy ZONEMD gradually, perhaps by 719 utilizing one of the private use hash algorithms listed in 720 Section 5.3. Similarly, recipients may want to initially configure 721 verification failures only as a warning, and later as an error after 722 gaining experience and confidence with the feature. 724 7. Performance Considerations 726 This section is provided to make zone publishers aware of the 727 performance requirements and implications of including ZONEMD RRs in 728 a zone. 730 7.1. SIMPLE SHA384 732 As mentioned previously, the SIMPLE scheme may not be appropriate for 733 use in zones that are either large or highly dynamic. Zone 734 publishers should carefully consider the use of ZONEMD in such zones, 735 since it might cause consumers of zone data (e.g., secondary name 736 servers) to expend resources on digest calculation. Furthermore, for 737 such use cases, it is recommended that ZONEMD only be used when 738 digest calculation time is significantly less than propagation times 739 and update intervals. 741 The authors' implementation (Section 10.1) includes an option to 742 record and report CPU usage of its operation. The software was used 743 to generate digests for more than 800 TLD zones available from 744 [CZDS]. The table below summarizes the the results for the SIMPLE 745 scheme and SHA384 hash algorithm grouped by zone size. The Rate 746 column is the mean amount of time per RR to calculate the digest, 747 running on commodity hardware at the time of this writing. 749 +---------------------+----------------+ 750 | Zone Size (RRs) | Rate (msec/RR) | 751 +---------------------+----------------+ 752 | 10 - 99 | 0.00683 | 753 | 100 - 999 | 0.00551 | 754 | 1000 - 9999 | 0.00505 | 755 | 10000 - 99999 | 0.00602 | 756 | 100000 - 999999 | 0.00845 | 757 | 1000000 - 9999999 | 0.0108 | 758 | 10000000 - 99999999 | 0.0148 | 759 +---------------------+----------------+ 761 For example, based on the above table, it takes approximately 0.13 762 seconds to calculate a SIMPLE SHA384 digest for a zone with 22,000 763 RRs, and about 2.5 seconds for a zone with 300,000 RRs. 765 These benchmarks attempt to emulate a worst-case scenario and take 766 into account the time required to canonicalize the zone for 767 processing. Each of the 800+ zones were measured three times, and 768 then averaged, with a different random sorting of the input data 769 prior to each measurement. 771 8. Privacy Considerations 773 This specification has no impact on user privacy. 775 9. Acknowledgments 777 The authors wish to thank David Blacka, Scott Hollenbeck, and Rick 778 Wilhelm for providing feedback on early drafts of this document. 779 Additionally, they thank Joe Abley, Mark Andrews, Ralph Dolmans, 780 Richard Gibson, Olafur Gudmundsson, Bob Harold, Paul Hoffman, Evan 781 Hunt, Shumon Huque, Tatuya Jinmei, Mike St. Johns, Burt Kaliski, 782 Shane Kerr, Matt Larson, John Levine, Ed Lewis, Matt Pounsett, Mukund 783 Sivaraman, Petr Spacek, Ondrej Sury, Willem Toorop, Florian Weimer, 784 Tim Wicinksi, Wouter Wijngarrds, Paul Wouters, and other members of 785 the dnsop working group for their input. 787 10. Implementation Status 789 10.1. Authors' Implementation 791 The authors have an open source implementation in C, using the ldns 792 library [ldns-zone-digest]. This implementation is able to perform 793 the following functions: 795 o Read an input zone and output a zone with the ZONEMD placeholder. 797 o Compute zone digest over signed zone and update the ZONEMD record. 799 o Re-compute DNSSEC signature over the ZONEMD record. 801 o Verify the zone digest from an input zone. 803 This implementation does not: 805 o Perform DNSSEC validation of the ZONEMD record during 806 verification. 808 10.2. Shane Kerr's Implementation 810 Shane Kerr wrote an implementation of this specification during the 811 IETF 102 hackathon [ZoneDigestHackathon]. This implementation is in 812 Python and is able to perform the following functions: 814 o Read an input zone and output a zone with ZONEMD record. 816 o Verify the zone digest from an input zone. 818 o Output the ZONEMD record in its defined presentation format. 820 This implementation does not: 822 o Re-compute DNSSEC signature over the ZONEMD record. 824 o Perform DNSSEC validation of the ZONEMD record. 826 10.3. NIC Chile Labs Implementation 828 NIC Chile Labs wrote an implementation of this specification as part 829 of "dns-tools" suite [DnsTools], which besides digesting, can also 830 sign and verify zones. This implementation is in Go and is able to 831 perform the following functions: 833 o Compute zone digest over signed zone and update the ZONEMD record. 835 o Verify the zone digest from an input zone. 837 o Perform DNSSEC validation of the ZONEMD record during 838 verification. 840 o Re-compute DNSSEC signature over the ZONEMD record. 842 11. Change Log 844 RFC Editor: Please remove this section. 846 This section lists substantial changes to the document as it is being 847 worked on. 849 From -00 to -01: 851 o Removed requirement to sort by RR CLASS. 853 o Added Kumari and Hardaker as coauthors. 855 o Added Change Log section. 857 o Minor clarifications and grammatical edits. 859 From -01 to -02: 861 o Emphasize desire for data security over channel security. 863 o Expanded motivation into its own subsection. 865 o Removed discussion topic whether or not to include serial in 866 ZONEMD. 868 o Clarified that a zone's NS records always sort before the SOA 869 record. 871 o Clarified that all records in the zone must are digested, except 872 as specified in the exclusion rules. 874 o Added for discussion out-of-zone and occluded records. 876 o Clarified that update of ZONEMD signature must not cause a serial 877 number change. 879 o Added persons to acknowledgments. 881 From -02 to -03: 883 o Added recommendation to set ZONEMD TTL to SOA TTL. 885 o Clarified that digest input uses uncompressed names. 887 o Updated Implementations section. 889 o Changed intended status from Standards Track to Experimental and 890 added Scope of Experiment section. 892 o Updated Motivation, Introduction, and Design Overview sections in 893 response to working group discussion. 895 o Gave ZONEMD digest types their own status, separate from DS digest 896 types. Request IANA to create a registry. 898 o Added Reserved field for future work supporting dynamic updates. 900 o Be more rigorous about having just ONE ZONEMD record in the zone. 902 o Expanded use cases. 904 From -03 to -04: 906 o Added an appendix with example zones and digests. 908 o Clarified that only apex ZONEMD RRs shall be processed. 910 From -04 to -05: 912 o Made SHA384 the only supported ZONEMD digest type. 914 o Disassociated ZONEMD digest types from DS digest types. 916 o Updates to Introduction based on list feedback. 918 o Changed "zone file" to "zone" everywhere. 920 o Restored text about why ZONEMD has a Serial field. 922 o Clarified ordering of RRSets having same owner to be numerically 923 ascending. 925 o Clarified that all duplicate RRs (not just SOA) must be suppressed 926 in digest calculation. 928 o Clarified that the Reserved field must be set to zero and checked 929 for zero in verification. 931 o Clarified that occluded data must be included. 933 o Clarified procedure for verification, using temporary location for 934 received digest. 936 o Explained why Reserved field is 8-bits. 938 o IANA Considerations section now more specific. 940 o Added complex zone to examples. 942 o 944 From -05 to -06: 946 o RR type code 63 was assigned to ZONEMD by IANA. 948 From -06 to -07: 950 o Fixed mistakes in ZONEMD examples. 952 o Added private use Digest Type values 240-254. 954 o Clarified that Digest field must not be empty. 956 From -07 to draft-ietf-dnsop-dns-zone-digest-00: 958 o Adopted by dnsop. 960 o Clarified further that non-apex ZONEMD RRs have no meaning. 962 o Changed "provably [un]signed" to "provably [in]secure". 964 o Allow multiple ZONEMD RRs to support algorithm agility/rollovers. 966 o Describe verification when there are multiple ZONEMD RRs. 968 From -00 to -01: 970 o Simplified requirements around verifying multiple digests. Any 971 one match is sufficient. 973 o Updated implementation notes. 975 o Both implementations produce expected results on examples given in 976 this document. 978 From -01 to -02: 980 o Changed the name of the Reserved field to Parameter. 982 o Changed the name of Digest Type 1 from SHA384 to SHA384-STABLE. 984 o The meaning of the Parameter field now depends on Digest Type. 986 o No longer require Parameter field to be zero in verification. 988 o Updated a rule from earlier versions that said multiple ZONEMD RRs 989 were not allowed. 991 From -02 to -03: 993 o Changed the name of Digest Type 1 from SHA384-STABLE to 994 SHA384-SIMPLE. 996 o Changed document status from Experimental to Standards Track. 998 o Removed Scope of Experimentation section. 1000 From -03 to -04: 1002 o Addressing WGLC feedback. 1004 o Changed from "Digest Type + Paramter" to "Scheme + Hash 1005 Algorithm". This should make it more obvious how ZONEMD can be 1006 expanded in the future with new schemes and hash algorithms, while 1007 sacrificing some of the flexibility that the Parameter was 1008 intended to provide. 1010 o Note: old RDATA fields: Serial, Digest Type, Parameter, Digest. 1012 o Note: new RDATA fields: Serial, Scheme, Hash Algorithm, Digest. 1014 o Add new IANA requirement for a Scheme registry. 1016 o Rearranged some sections and separated scheme-specific aspects 1017 from general aspects of digest calculation. 1019 o When discussing multiple ZONEMD RRs, allow for Scheme, as well as 1020 Hash Algorithm, transition. 1022 o Added Performance Considerations section with some benchmarks. 1024 o Further clarifications about non-apex ZONEMD RRs. 1026 o Clarified inclusion rule for duplicate RRs. 1028 o Removed or lowercased some inappropriately used RFC 2119 key 1029 words. 1031 o Clarified that all ZONEMD RRs, even for unsupported hash 1032 algorithms, must be zeroized during digest calculation. 1034 o Added Resilience and Fragility to security considerations. 1036 o Updated examples since changes in this version result in different 1037 hash values. 1039 From -04 to -05: 1041 o Clarifications about non-apex and multiple ZONEMD RRs. 1043 o Clarifications about benchmark results. 1045 o Don't compute ZONEMD on-the-fly. 1047 o Specifciation Required for updates to ZONEMD protocol registries. 1049 o Other rewording based on WGLC feedback. 1051 o Updated RFC numbers for some references. 1053 o Use documentation IP addresses instead of loopback. 1055 o Updated examples in the appendix. 1057 From -05 to -06: 1059 o Per WG suggestion, no longer include any apex ZONEMD record in 1060 digest calculation. 1062 o Updated examples in the appendix. 1064 o Clarified verification procedure by describing a loop over all 1065 ZONEMD RRs. 1067 From -06 to -07: 1069 o Added NIC Chile Labs implementation. 1071 From -07 to -08: 1073 o Update an author's affiliation. 1075 o Clarified why placeholder RRs are still important (for NSEC/ 1076 NSEC3). 1078 o Moved subsection ("Order of RRSets Having the Same Owner Name") 1079 with single sentence paragraph up into parent section. 1081 12. References 1083 12.1. Normative References 1085 [RFC1034] Mockapetris, P., "Domain names - concepts and facilities", 1086 STD 13, RFC 1034, DOI 10.17487/RFC1034, November 1987, 1087 . 1089 [RFC1035] Mockapetris, P., "Domain names - implementation and 1090 specification", STD 13, RFC 1035, DOI 10.17487/RFC1035, 1091 November 1987, . 1093 [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate 1094 Requirement Levels", BCP 14, RFC 2119, 1095 DOI 10.17487/RFC2119, March 1997, 1096 . 1098 [RFC4034] Arends, R., Austein, R., Larson, M., Massey, D., and S. 1099 Rose, "Resource Records for the DNS Security Extensions", 1100 RFC 4034, DOI 10.17487/RFC4034, March 2005, 1101 . 1103 [RFC6234] Eastlake 3rd, D. and T. Hansen, "US Secure Hash Algorithms 1104 (SHA and SHA-based HMAC and HKDF)", RFC 6234, 1105 DOI 10.17487/RFC6234, May 2011, 1106 . 1108 [RFC8174] Leiba, B., "Ambiguity of Uppercase vs Lowercase in RFC 1109 2119 Key Words", BCP 14, RFC 8174, DOI 10.17487/RFC8174, 1110 May 2017, . 1112 12.2. Informative References 1114 [CZDS] Internet Corporation for Assigned Names and Numbers, 1115 "Centralized Zone Data Service", October 2018, 1116 . 1118 [DnsTools] 1119 NIC Chile Labs, "DNS tools for zone signature (file, 1120 pkcs11-hsm) and validation, and zone digest (ZONEMD)", 1121 April 2020, . 1123 [InterNIC] 1124 ICANN, "InterNIC FTP site", May 2018, 1125 . 1127 [ldns-zone-digest] 1128 Verisign, "Implementation of Message Digests for DNS Zones 1129 using the ldns library", July 2018, 1130 . 1132 [RFC1995] Ohta, M., "Incremental Zone Transfer in DNS", RFC 1995, 1133 DOI 10.17487/RFC1995, August 1996, 1134 . 1136 [RFC2065] Eastlake 3rd, D. and C. Kaufman, "Domain Name System 1137 Security Extensions", RFC 2065, DOI 10.17487/RFC2065, 1138 January 1997, . 1140 [RFC2136] Vixie, P., Ed., Thomson, S., Rekhter, Y., and J. Bound, 1141 "Dynamic Updates in the Domain Name System (DNS UPDATE)", 1142 RFC 2136, DOI 10.17487/RFC2136, April 1997, 1143 . 1145 [RFC2535] Eastlake 3rd, D., "Domain Name System Security 1146 Extensions", RFC 2535, DOI 10.17487/RFC2535, March 1999, 1147 . 1149 [RFC2845] Vixie, P., Gudmundsson, O., Eastlake 3rd, D., and B. 1150 Wellington, "Secret Key Transaction Authentication for DNS 1151 (TSIG)", RFC 2845, DOI 10.17487/RFC2845, May 2000, 1152 . 1154 [RFC2931] Eastlake 3rd, D., "DNS Request and Transaction Signatures 1155 ( SIG(0)s )", RFC 2931, DOI 10.17487/RFC2931, September 1156 2000, . 1158 [RFC4880] Callas, J., Donnerhacke, L., Finney, H., Shaw, D., and R. 1159 Thayer, "OpenPGP Message Format", RFC 4880, 1160 DOI 10.17487/RFC4880, November 2007, 1161 . 1163 [RFC5751] Ramsdell, B. and S. Turner, "Secure/Multipurpose Internet 1164 Mail Extensions (S/MIME) Version 3.2 Message 1165 Specification", RFC 5751, DOI 10.17487/RFC5751, January 1166 2010, . 1168 [RFC5936] Lewis, E. and A. Hoenes, Ed., "DNS Zone Transfer Protocol 1169 (AXFR)", RFC 5936, DOI 10.17487/RFC5936, June 2010, 1170 . 1172 [RFC7696] Housley, R., "Guidelines for Cryptographic Algorithm 1173 Agility and Selecting Mandatory-to-Implement Algorithms", 1174 BCP 201, RFC 7696, DOI 10.17487/RFC7696, November 2015, 1175 . 1177 [RFC7706] Kumari, W. and P. Hoffman, "Decreasing Access Time to Root 1178 Servers by Running One on Loopback", RFC 7706, 1179 DOI 10.17487/RFC7706, November 2015, 1180 . 1182 [RFC7858] Hu, Z., Zhu, L., Heidemann, J., Mankin, A., Wessels, D., 1183 and P. Hoffman, "Specification for DNS over Transport 1184 Layer Security (TLS)", RFC 7858, DOI 10.17487/RFC7858, May 1185 2016, . 1187 [RFC8126] Cotton, M., Leiba, B., and T. Narten, "Guidelines for 1188 Writing an IANA Considerations Section in RFCs", BCP 26, 1189 RFC 8126, DOI 10.17487/RFC8126, June 2017, 1190 . 1192 [RFC8484] Hoffman, P. and P. McManus, "DNS Queries over HTTPS 1193 (DoH)", RFC 8484, DOI 10.17487/RFC8484, October 2018, 1194 . 1196 [RFC8499] Hoffman, P., Sullivan, A., and K. Fujiwara, "DNS 1197 Terminology", BCP 219, RFC 8499, DOI 10.17487/RFC8499, 1198 January 2019, . 1200 [RootServers] 1201 Root Server Operators, "Root Server Technical Operations", 1202 July 2018, . 1204 [RPZ] Vixie, P. and V. Schryver, "DNS Response Policy Zones 1205 (RPZ)", draft-vixie-dnsop-dns-rpz-00 (work in progress), 1206 June 2018, . 1209 [ZoneDigestHackathon] 1210 Kerr, S., "Prototype implementation of ZONEMD for the IETF 1211 102 hackathon in Python", July 2018, 1212 . 1214 Appendix A. Example Zones With Digests 1216 This appendix contains example zones with accurate ZONEMD records. 1217 These can be used to verify an implementation of the zone digest 1218 protocol. 1220 A.1. Simple EXAMPLE Zone 1222 Here, the EXAMPLE zone contains an SOA record, NS and glue records, 1223 and a ZONEMD record. 1225 example. 86400 IN SOA ns1 admin 2018031900 ( 1226 1800 900 604800 86400 ) 1227 86400 IN NS ns1 1228 86400 IN NS ns2 1229 86400 IN ZONEMD 2018031900 1 1 ( 1230 c68090d90a7aed71 1231 6bc459f9340e3d7c 1232 1370d4d24b7e2fc3 1233 a1ddc0b9a87153b9 1234 a9713b3c9ae5cc27 1235 777f98b8e730044c ) 1236 ns1 3600 IN A 203.0.113.63 1237 ns2 3600 IN AAAA 2001:db8::63 1239 A.2. Complex EXAMPLE Zone 1241 Here, the EXAMPLE zone contains duplicate RRs, and an occluded RR, 1242 and one out-of-zone RR. 1244 example. 86400 IN SOA ns1 admin 2018031900 ( 1245 1800 900 604800 86400 ) 1246 86400 IN NS ns1 1247 86400 IN NS ns2 1248 86400 IN ZONEMD 2018031900 1 1 ( 1249 31cefb03814f5062 1250 ad12fa951ba0ef5f 1251 8da6ae354a415767 1252 246f7dc932ceb1e7 1253 42a2108f529db6a3 1254 3a11c01493de358d ) 1255 ns1 3600 IN A 203.0.113.63 1256 ns2 3600 IN AAAA 2001:db8::63 1257 occluded.sub 7200 IN TXT "I'm occluded but must be digested" 1258 sub 7200 IN NS ns1 1259 duplicate 300 IN TXT "I must be digested just once" 1260 duplicate 300 IN TXT "I must be digested just once" 1261 foo.test. 555 IN TXT "out-of-zone data must be excluded" 1262 non-apex 900 IN ZONEMD 2018031900 1 1 ( 1263 616c6c6f77656420 1264 6275742069676e6f 1265 7265642e20616c6c 1266 6f77656420627574 1267 2069676e6f726564 1268 2e20616c6c6f7765 ) 1270 A.3. EXAMPLE Zone with multiple digests 1272 Here, the EXAMPLE zone contains multiple ZONEMD records. Since only 1273 one Scheme (SIMPLE) and one Hash Algorithm (SHA384) is defined at 1274 this time, this example utilizes additional ZONEMD records with 1275 Scheme and Hash Algorithm values in the private range (240-254). 1276 These additional private-range digests are not verifiable. 1278 example. 86400 IN SOA ns1 admin 2018031900 ( 1279 1800 900 604800 86400 ) 1280 example. 86400 IN NS ns1.example. 1281 example. 86400 IN NS ns2.example. 1282 example. 86400 IN ZONEMD 2018031900 1 1 ( 1283 62e6cf51b02e54b9 1284 b5f967d547ce4313 1285 6792901f9f88e637 1286 493daaf401c92c27 1287 9dd10f0edb1c56f8 1288 080211f8480ee306 ) 1289 example. 86400 IN ZONEMD 2018031900 1 240 ( 1290 e2d523f654b9422a 1291 96c5a8f44607bbee ) 1292 example. 86400 IN ZONEMD 2018031900 241 1 ( 1293 e1846540e33a9e41 1294 89792d18d5d131f6 1295 05fc283e ) 1296 ns1.example. 3600 IN A 203.0.113.63 1297 ns2.example. 86400 IN TXT "This example has multiple digests" 1298 ns2.example. 3600 IN AAAA 2001:db8::63 1300 A.4. The URI.ARPA Zone 1302 The URI.ARPA zone retrieved 2018-10-21. Note this sample zone has 1303 (expired) signatures, but no signature for the ZONEMD RR. 1305 ; <<>> DiG 9.9.4 <<>> @lax.xfr.dns.icann.org uri.arpa axfr 1306 ; (2 servers found) 1307 ;; global options: +cmd 1308 uri.arpa. 3600 IN SOA sns.dns.icann.org. ( 1309 noc.dns.icann.org. 2018100702 10800 3600 1209600 3600 ) 1310 uri.arpa. 3600 IN RRSIG NSEC 8 2 3600 ( 1311 20181028142623 20181007205525 47155 uri.arpa. 1312 eEC4w/oXLR1Epwgv4MBiDtSBsXhqrJVvJWUpbX8XpetAvD35bxwNCUTi 1313 /pAJVUXefegWeiriD2rkTgCBCMmn7YQIm3gdR+HjY/+o3BXNQnz97f+e 1314 HAE9EDDzoNVfL1PyV/2fde9tDeUuAGVVwmD399NGq9jWYMRpyri2kysr q/g= ) 1315 uri.arpa. 86400 IN RRSIG NS 8 2 86400 ( 1316 20181028172020 20181007175821 47155 uri.arpa. 1317 ATyV2A2A8ZoggC+68u4GuP5MOUuR+2rr3eWOkEU55zAHld/7FiBxl4ln 1318 4byJYy7NudUwlMOEXajqFZE7DVl8PpcvrP3HeeGaVzKqaWj+aus0jbKF 1319 Bsvs2b1qDZemBfkz/IfAhUTJKnto0vSUicJKfItu0GjyYNJCz2CqEuGD Wxc= ) 1320 uri.arpa. 600 IN RRSIG MX 8 2 600 ( 1321 20181028170556 20181007175821 47155 uri.arpa. 1322 e7/r3KXDohX1lyVavetFFObp8fB8aXT76HnN9KCQDxSnSghNM83UQV0t 1323 lTtD8JVeN1mCvcNFZpagwIgB7XhTtm6Beur/m5ES+4uSnVeS6Q66HBZK 1324 A3mR95IpevuVIZvvJ+GcCAQpBo6KRODYvJ/c/ZG6sfYWkZ7qg/Em5/+3 4UI= ) 1325 uri.arpa. 3600 IN RRSIG DNSKEY 8 2 3600 ( 1326 20181028152832 20181007175821 15796 uri.arpa. 1327 nzpbnh0OqsgBBP8St28pLvPEQ3wZAUdEBuUwil+rtjjWlYYiqjPxZ286 1328 XF4Rq1usfV5x71jZz5IqswOaQgia91ylodFpLuXD6FTGs2nXGhNKkg1V 1329 chHgtwj70mXU72GefVgo8TxrFYzxuEFP5ZTP92t97FVWVVyyFd86sbbR 1330 6DZj3uA2wEvqBVLECgJLrMQ9Yy7MueJl3UA4h4E6zO2JY9Yp0W9woq0B 1331 dqkkwYTwzogyYffPmGAJG91RJ2h6cHtFjEZe2MnaY2glqniZ0WT9vXXd 1332 uFPm0KD9U77Ac+ZtctAF9tsZwSdAoL365E2L1usZbA+K0BnPPqGFJRJk 1333 5R0A1w== ) 1334 uri.arpa. 3600 IN RRSIG DNSKEY 8 2 3600 ( 1335 20181028152832 20181007175821 55480 uri.arpa. 1336 lWtQV/5szQjkXmbcD47/+rOW8kJPksRFHlzxxmzt906+DBYyfrH6uq5X 1337 nHvrUlQO6M12uhqDeL+bDFVgqSpNy+42/OaZvaK3J8EzPZVBHPJykKMV 1338 63T83aAiJrAyHzOaEdmzLCpalqcEE2ImzlLHSafManRfJL8Yuv+JDZFj 1339 2WDWfEcUuwkmIZWX11zxp+DxwzyUlRl7x4+ok5iKZWIg5UnBAf6B8T75 1340 WnXzlhCw3F2pXI0a5LYg71L3Tp/xhjN6Yy9jGlIRf5BjB59X2zra3a2R 1341 PkI09SSnuEwHyF1mDaV5BmQrLGRnCjvwXA7ho2m+vv4SP5dUdXf+GTeA 1342 1HeBfw== ) 1343 uri.arpa. 3600 IN RRSIG SOA 8 2 3600 ( 1344 20181029114753 20181008222815 47155 uri.arpa. 1345 qn8yBNoHDjGdT79U2Wu9IIahoS0YPOgYP8lG+qwPcrZ1BwGiHywuoUa2 1346 Mx6BWZlg+HDyaxj2iOmox+IIqoUHhXUbO7IUkJFlgrOKCgAR2twDHrXu 1347 9BUQHy9SoV16wYm3kBTEPyxW5FFm8vcdnKAF7sxSY8BbaYNpRIEjDx4A JUc= ) 1348 uri.arpa. 3600 IN NSEC ftp.uri.arpa. NS SOA ( 1349 MX RRSIG NSEC DNSKEY ) 1350 uri.arpa. 86400 IN NS a.iana-servers.net. 1351 uri.arpa. 86400 IN NS b.iana-servers.net. 1352 uri.arpa. 86400 IN NS c.iana-servers.net. 1353 uri.arpa. 86400 IN NS ns2.lacnic.net. 1354 uri.arpa. 86400 IN NS sec3.apnic.net. 1355 uri.arpa. 600 IN MX 10 pechora.icann.org. 1356 uri.arpa. 3600 IN DNSKEY 256 3 8 ( 1357 AwEAAcBi7tSart2J599zbYWspMNGN70IBWb4ziqyQYH9MTB/VCz6WyUK 1358 uXunwiJJbbQ3bcLqTLWEw134B6cTMHrZpjTAb5WAwg4XcWUu8mdcPTiL 1359 Bl6qVRlRD0WiFCTzuYUfkwsh1Rbr7rvrxSQhF5rh71zSpwV5jjjp65Wx 1360 SdJjlH0B ) 1361 uri.arpa. 3600 IN DNSKEY 257 3 8 ( 1362 AwEAAbNVv6ulgRdO31MtAehz7j3ALRjwZglWesnzvllQl/+hBRZr9QoY 1363 cO2I+DkO4Q1NKxox4DUIxj8SxPO3GwDuOFR9q2/CFi2O0mZjafbdYtWc 1364 3zSdBbi3q0cwCIx7GuG9eqlL+pg7mdk9dgdNZfHwB0LnqTD8ebLPsrO/ 1365 Id7kBaiqYOfMlZnh2fp+2h6OOJZHtY0DK1UlssyB5PKsE0tVzo5s6zo9 1366 iXKe5u+8WTMaGDY49vG80JPAKE7ezMiH/NZcUMiE0PRZ8D3foq2dYuS5 1367 ym+vA83Z7v8A+Rwh4UGnjxKB8zmr803V0ASAmHz/gwH5Vb0nH+LObwFt 1368 l3wpbp+Wpm8= ) 1369 uri.arpa. 3600 IN DNSKEY 257 3 8 ( 1370 AwEAAbwnFTakCvaUKsXji4mgmxZUJi1IygbnGahbkmFEa0L16J+TchKR 1371 wcgzVfsxUGa2MmeA4hgkAooC3uy+tTmoMsgy8uq/JAj24DjiHzd46LfD 1372 FK/qMidVqFpYSHeq2Vv5ojkuIsx4oe4KsafGWYNOczKZgH5loGjN2aJG 1373 mrIm++XCphOskgCsQYl65MIzuXffzJyxlAuts+ecAIiVeqRaqQfr8LRU 1374 7wIsLxinXirprtQrbor+EtvlHp9qXE6ARTZDzf4jvsNpKvLFZtmxzFf3 1375 e/UJz5eHjpwDSiZL7xE8aE1o1nGfPtJx9ZnB3bapltaJ5wY+5XOCKgY0 1376 xmJVvNQlwdE= ) 1377 ftp.uri.arpa. 3600 IN RRSIG NSEC 8 3 3600 ( 1378 20181028080856 20181007175821 47155 uri.arpa. 1379 HClGAqPxzkYkAT7Q/QNtQeB6YrkP6EPOef+9Qo5/2zngwAewXEAQiyF9 1380 jD1USJiroM11QqBS3v3aIdW/LXORs4Ez3hLcKNO1cKHsOuWAqzmE+BPP 1381 Arfh8N95jqh/q6vpaB9UtMkQ53tM2fYU1GszOLN0knxbHgDHAh2axMGH lqM= ) 1382 ftp.uri.arpa. 604800 IN RRSIG NAPTR 8 3 604800 ( 1383 20181028103644 20181007205525 47155 uri.arpa. 1384 WoLi+vZzkxaoLr2IGZnwkRvcDf6KxiWQd1WZP/U+AWnV+7MiqsWPZaf0 1385 9toRErerGoFOiOASNxZjBGJrRgjmavOM9U+LZSconP9zrNFd4dIu6kp5 1386 YxlQJ0uHOvx1ZHFCj6lAt1ACUIw04ZhMydTmi27c8MzEOMepvn7iH7r7 k7k= ) 1387 ftp.uri.arpa. 3600 IN NSEC http.uri.arpa. NAPTR ( 1388 RRSIG NSEC ) 1389 ftp.uri.arpa. 604800 IN NAPTR 0 0 "" "" ( 1390 "!^ftp://([^:/?#]*).*$!\\1!i" . ) 1391 http.uri.arpa. 3600 IN RRSIG NSEC 8 3 3600 ( 1392 20181029010647 20181007175821 47155 uri.arpa. 1393 U03NntQ73LHWpfLmUK8nMsqkwVsOGW2KdsyuHYAjqQSZvKbtmbv7HBmE 1394 H1+Ii3Z+wtfdMZBy5aC/6sHdx69BfZJs16xumycMlAy6325DKTQbIMN+ 1395 ift9GrKBC7cgCd2msF/uzSrYxxg4MJQzBPvlkwXnY3b7eJSlIXisBIn7 3b8= ) 1396 http.uri.arpa. 604800 IN RRSIG NAPTR 8 3 604800 ( 1397 20181029011815 20181007205525 47155 uri.arpa. 1398 T7mRrdag+WSmG+n22mtBSQ/0Y3v+rdDnfQV90LN5Fq32N5K2iYFajF7F 1399 Tp56oOznytfcL4fHrqOE0wRc9NWOCCUec9C7Wa1gJQcllEvgoAM+L6f0 1400 RsEjWq6+9jvlLKMXQv0xQuMX17338uoD/xiAFQSnDbiQKxwWMqVAimv5 7Zs= ) 1401 http.uri.arpa. 3600 IN NSEC mailto.uri.arpa. NAPTR ( 1402 RRSIG NSEC ) 1403 http.uri.arpa. 604800 IN NAPTR 0 0 "" "" ( 1404 "!^http://([^:/?#]*).*$!\\1!i" . ) 1405 mailto.uri.arpa. 3600 IN RRSIG NSEC 8 3 3600 ( 1406 20181028110727 20181007175821 47155 uri.arpa. 1407 GvxzVL85rEukwGqtuLxek9ipwjBMfTOFIEyJ7afC8HxVMs6mfFa/nEM/ 1408 IdFvvFg+lcYoJSQYuSAVYFl3xPbgrxVSLK125QutCFMdC/YjuZEnq5cl 1409 fQciMRD7R3+znZfm8d8u/snLV9w4D+lTBZrJJUBe1Efc8vum5vvV7819 ZoY= ) 1410 mailto.uri.arpa. 604800 IN RRSIG NAPTR 8 3 604800 ( 1411 20181028141825 20181007205525 47155 uri.arpa. 1412 MaADUgc3fc5v++M0YmqjGk3jBdfIA5RuP62hUSlPsFZO4k37erjIGCfF 1413 j+g84yc+QgbSde0PQHszl9fE/+SU5ZXiS9YdcbzSZxp2erFpZOTchrpg 1414 916T4vx6i59scodjb0l6bDyZ+mtIPrc1w6b4hUyOUTsDQoAJYxdfEuMg Vy4= ) 1415 mailto.uri.arpa. 3600 IN NSEC urn.uri.arpa. NAPTR ( 1416 RRSIG NSEC ) 1417 mailto.uri.arpa. 604800 IN NAPTR 0 0 "" "" ( 1418 "!^mailto:(.*)@(.*)$!\\2!i" . ) 1419 urn.uri.arpa. 3600 IN RRSIG NSEC 8 3 3600 ( 1420 20181028123243 20181007175821 47155 uri.arpa. 1421 Hgsw4Deops1O8uWyELGe6hpR/OEqCnTHvahlwiQkHhO5CSEQrbhmFAWe 1422 UOkmGAdTEYrSz+skLRQuITRMwzyFf4oUkZihGyhZyzHbcxWfuDc/Pd/9 1423 DSl56gdeBwy1evn5wBTms8yWQVkNtphbJH395gRqZuaJs3LD/qTyJ5Dp LvA= ) 1424 urn.uri.arpa. 604800 IN RRSIG NAPTR 8 3 604800 ( 1425 20181029071816 20181007205525 47155 uri.arpa. 1426 ALIZD0vBqAQQt40GQ0Efaj8OCyE9xSRJRdyvyn/H/wZVXFRFKrQYrLAS 1427 D/K7q6CMTOxTRCu2J8yes63WJiaJEdnh+dscXzZkmOg4n5PsgZbkvUSW 1428 BiGtxvz5jNncM0xVbkjbtByrvJQAO1cU1mnlDKe1FmVB1uLpVdA9Ib4J hMU= ) 1429 urn.uri.arpa. 3600 IN NSEC uri.arpa. NAPTR RRSIG ( 1430 NSEC ) 1431 urn.uri.arpa. 604800 IN NAPTR 0 0 "" "" ( 1432 "/urn:([^:]+)/\\1/i" . ) 1433 uri.arpa. 3600 IN SOA sns.dns.icann.org. ( 1434 noc.dns.icann.org. 2018100702 10800 3600 1209600 3600 ) 1435 ;; Query time: 66 msec 1436 ;; SERVER: 192.0.32.132#53(192.0.32.132) 1437 ;; WHEN: Sun Oct 21 20:39:28 UTC 2018 1438 ;; XFR size: 34 records (messages 1, bytes 3941) 1439 uri.arpa. 3600 IN ZONEMD 2018100702 1 1 ( 1440 1291b78ddf7669b1a39d014d87626b709b55774c5d7d58fa 1441 dc556439889a10eaf6f11d615900a4f996bd46279514e473 ) 1443 A.5. The ROOT-SERVERS.NET Zone 1445 The ROOT-SERVERS.NET zone retreived 2018-10-21. 1447 root-servers.net. 3600000 IN SOA a.root-servers.net. ( 1448 nstld.verisign-grs.com. 2018091100 14400 7200 1209600 3600000 ) 1449 root-servers.net. 3600000 IN NS a.root-servers.net. 1450 root-servers.net. 3600000 IN NS b.root-servers.net. 1451 root-servers.net. 3600000 IN NS c.root-servers.net. 1452 root-servers.net. 3600000 IN NS d.root-servers.net. 1453 root-servers.net. 3600000 IN NS e.root-servers.net. 1454 root-servers.net. 3600000 IN NS f.root-servers.net. 1455 root-servers.net. 3600000 IN NS g.root-servers.net. 1456 root-servers.net. 3600000 IN NS h.root-servers.net. 1457 root-servers.net. 3600000 IN NS i.root-servers.net. 1458 root-servers.net. 3600000 IN NS j.root-servers.net. 1459 root-servers.net. 3600000 IN NS k.root-servers.net. 1460 root-servers.net. 3600000 IN NS l.root-servers.net. 1461 root-servers.net. 3600000 IN NS m.root-servers.net. 1462 a.root-servers.net. 3600000 IN AAAA 2001:503:ba3e::2:30 1463 a.root-servers.net. 3600000 IN A 198.41.0.4 1464 b.root-servers.net. 3600000 IN MX 20 mail.isi.edu. 1465 b.root-servers.net. 3600000 IN AAAA 2001:500:200::b 1466 b.root-servers.net. 3600000 IN A 199.9.14.201 1467 c.root-servers.net. 3600000 IN AAAA 2001:500:2::c 1468 c.root-servers.net. 3600000 IN A 192.33.4.12 1469 d.root-servers.net. 3600000 IN AAAA 2001:500:2d::d 1470 d.root-servers.net. 3600000 IN A 199.7.91.13 1471 e.root-servers.net. 3600000 IN AAAA 2001:500:a8::e 1472 e.root-servers.net. 3600000 IN A 192.203.230.10 1473 f.root-servers.net. 3600000 IN AAAA 2001:500:2f::f 1474 f.root-servers.net. 3600000 IN A 192.5.5.241 1475 g.root-servers.net. 3600000 IN AAAA 2001:500:12::d0d 1476 g.root-servers.net. 3600000 IN A 192.112.36.4 1477 h.root-servers.net. 3600000 IN AAAA 2001:500:1::53 1478 h.root-servers.net. 3600000 IN A 198.97.190.53 1479 i.root-servers.net. 3600000 IN MX 10 mx.i.root-servers.org. 1480 i.root-servers.net. 3600000 IN AAAA 2001:7fe::53 1481 i.root-servers.net. 3600000 IN A 192.36.148.17 1482 j.root-servers.net. 3600000 IN AAAA 2001:503:c27::2:30 1483 j.root-servers.net. 3600000 IN A 192.58.128.30 1484 k.root-servers.net. 3600000 IN AAAA 2001:7fd::1 1485 k.root-servers.net. 3600000 IN A 193.0.14.129 1486 l.root-servers.net. 3600000 IN AAAA 2001:500:9f::42 1487 l.root-servers.net. 3600000 IN A 199.7.83.42 1488 m.root-servers.net. 3600000 IN AAAA 2001:dc3::35 1489 m.root-servers.net. 3600000 IN A 202.12.27.33 1490 root-servers.net. 3600000 IN SOA a.root-servers.net. ( 1491 nstld.verisign-grs.com. 2018091100 14400 7200 1209600 3600000 ) 1492 root-servers.net. 3600000 IN ZONEMD 2018091100 1 1 ( 1493 f1ca0ccd91bd5573d9f431c00ee0101b2545c97602be0a97 1494 8a3b11dbfc1c776d5b3e86ae3d973d6b5349ba7f04340f79 ) 1496 Authors' Addresses 1498 Duane Wessels 1499 Verisign 1500 12061 Bluemont Way 1501 Reston, VA 20190 1503 Phone: +1 703 948-3200 1504 Email: dwessels@verisign.com 1505 URI: http://verisign.com 1507 Piet Barber 1508 Verisign 1509 12061 Bluemont Way 1510 Reston, VA 20190 1512 Phone: +1 703 948-3200 1513 Email: pbarber@verisign.com 1514 URI: http://verisign.com 1516 Matt Weinberg 1517 Amazon 1519 Email: matweinb@amazon.com 1520 URI: http://amazon.com 1522 Warren Kumari 1523 Google 1524 1600 Amphitheatre Parkway 1525 Mountain View, CA 94043 1527 Email: warren@kumari.net 1529 Wes Hardaker 1530 USC/ISI 1531 P.O. Box 382 1532 Davis, CA 95617 1534 Email: ietf@hardakers.net