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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: August 24, 2020 Verisign 6 W. Kumari 7 Google 8 W. Hardaker 9 USC/ISI 10 February 21, 2020 12 Message Digest for DNS Zones 13 draft-ietf-dnsop-dns-zone-digest-04 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 August 24, 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 . . . . . . . . . . . . . . 11 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 4.1. Verifying Multiple Digests . . . . . . . . . . . . . . . 14 100 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 the Zone Digest . . . . . . . . . . . . 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 11. Change Log . . . . . . . . . . . . . . . . . . . . . . . . . 18 116 12. References . . . . . . . . . . . . . . . . . . . . . . . . . 22 117 12.1. Normative References . . . . . . . . . . . . . . . . . . 22 118 12.2. Informative References . . . . . . . . . . . . . . . . . 23 119 Appendix A. Example Zones With Digests . . . . . . . . . . . . . 25 120 A.1. Simple EXAMPLE Zone . . . . . . . . . . . . . . . . . . . 25 121 A.2. Complex EXAMPLE Zone . . . . . . . . . . . . . . . . . . 26 122 A.3. EXAMPLE Zone with multiple digests . . . . . . . . . . . 26 123 A.4. The URI.ARPA Zone . . . . . . . . . . . . . . . . . . . . 27 124 A.5. The ROOT-SERVERS.NET Zone . . . . . . . . . . . . . . . . 30 125 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 32 127 1. Introduction 129 In the DNS, a zone is the collection of authoritative resource 130 records (RRs) sharing a common origin ([RFC7719]). 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 [dns-over-https], 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. Thus, changes to delegation and glue 207 records cannot be detected by DNSSEC alone. Furthermore, zones that 208 employ NSEC3 with opt-out are susceptible to the removal or addition 209 of names between the signed nodes. Whereas DNSSEC is primarily 210 designed to protect consumers of DNS response messages, this protocol 211 is designed to protect consumers of zones. 213 There are existing tools and protocols that provide data security, 214 such as OpenPGP [RFC4880] and S/MIME [RFC3851]. In fact, the 215 internic.net site publishes PGP signatures along side the root zone 216 and other files available there. However, this is a detached 217 signature with no strong association to the corresponding zone file 218 other than its timestamp. Non-detached signatures are, of course, 219 possible, but these necessarily change the format of the file being 220 distributed. That is, a zone signed with OpenPGP or S/MIME no longer 221 looks like a DNS zone and could not directly be loaded into a name 222 server. Once loaded the signature data is lost, so it does not 223 survive further propagation. 225 It seems the desire for data security in DNS zones was envisioned as 226 far back as 1997. [RFC2065] is an obsoleted specification of the 227 first generation DNSSEC Security Extensions. It describes a zone 228 transfer signature, aka AXFR SIG, which is similar to the technique 229 proposed by this document. That is, it proposes ordering all 230 (signed) RRSets in a zone, hashing their contents, and then signing 231 the zone hash. The AXFR SIG is described only for use during zone 232 transfers. It did not postulate the need to validate zone data 233 distributed outside of the DNS. Furthermore, its successor, 234 [RFC2535], omits the AXFR SIG, while at the same time introducing an 235 IXFR SIG. 237 1.2. Design Overview 239 This document introduces a new Resource Record type designed to 240 convey a message digest of the content of a zone. The digest is 241 calculated at the time of zone publication. Ideally the zone is 242 signed with DNSSEC to guarantee that any modifications of the digest 243 can be detected. The procedures for digest calculation and DNSSEC 244 signing are similar (i.e., both require the same ordering of RRs) and 245 can be done in parallel. 247 The zone digest is designed to be used on zones that are relatively 248 stable and have infrequent updates. As currently specified, the 249 digest is re-calculated over the entire zone content each time. This 250 specification does not provide an efficient mechanism for incremental 251 updates of zone data. It is, however, extensible so that future 252 schemes to support incremental zone digest algorithms (e.g. using 253 Merkle trees) can be accommodated. 255 It is expected that verification of a zone digest would be 256 implemented in name server software. That is, a name server can 257 verify the zone data it was given and refuse to serve a zone which 258 fails verification. For signed zones, the name server needs a trust 259 anchor to perform DNSSEC validation. For signed non-root zones, the 260 name server may need to send queries to validate a chain-of-trust. 261 Digest verification could also be performed externally. 263 1.3. Use Cases 265 1.3.1. Root Zone 267 The root zone [InterNIC] is one of the most widely distributed DNS 268 zone on the Internet, served by more than 1000 separate instances 269 [RootServers] at the time of this writing. Additionally, many 270 organizations configure their own name servers to serve the root zone 271 locally. Reasons for doing so include privacy and reduced access 272 time. [RFC7706] describes one, but not the only, way to do this. As 273 the root zone spreads beyond its traditional deployment boundaries, 274 the need for verification of the completeness of the zone contents 275 becomes increasingly important. 277 1.3.2. Providers, Secondaries, and Anycast 279 Since its very early days, the developers of the DNS recognized the 280 importance of secondary name servers and service diversity. However, 281 they may not have anticipated the complexity of modern DNS service 282 provisioning which can include multiple third-party providers and 283 hundreds of anycast instances. Instead of a simple primary-to- 284 secondary zone distribution system, today it is possible to have 285 multiple levels, multiple parties, and multiple protocols involved in 286 the distribution of zone data. This complexity introduces new places 287 for problems to arise. The zone digest protects the integrity of 288 data that flows through such systems. 290 1.3.3. Response Policy Zones 292 DNS Response Policy Zones is "a method of expressing DNS response 293 policy information inside specially constructed DNS zones..." [RPZ]. 294 A number of companies provide RPZ feeds, which can be consumed by 295 name server and firewall products. Since these are zones, AXFR is 296 often, but not necessarily used for transmission. While RPZ zones 297 can certainly be signed with DNSSEC, the data is not queried 298 directly, and would not be subject to DNSSEC validation. 300 1.3.4. Centralized Zone Data Service 302 ICANN operates the Centralized Zone Data Service [CZDS], which is a 303 repository of top-level domain zone files. Users request access to 304 the system, and to individual zones, and are then able to download 305 zone data for certain uses. Adding a zone digest to these would 306 provide CZDS users with assurances that the data has not been 307 modified. Note that ZONEMD could be added to CZDS zone data 308 independently of the zone served by production name servers. 310 1.3.5. General Purpose Comparison Check 312 Since the zone digest does not depend on presentation format, it 313 could be used to compare multiple copies of a zone received from 314 different sources, or copies generated by different processes. 316 1.4. Requirements Language 318 The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", 319 "SHOULD", "SHOULD NOT", "RECOMMENDED", "NOT RECOMMENDED", "MAY", and 320 "OPTIONAL" in this document are to be interpreted as described in BCP 321 14 [RFC2119] [RFC8174] when, and only when, they appear in all 322 capitals, as shown here. 324 2. The ZONEMD Resource Record 326 This section describes the ZONEMD Resource Record, including its 327 fields, wire format, and presentation format. The Type value for the 328 ZONEMD RR is 63. The ZONEMD RR is class independent. The RDATA of 329 the resource record consists of four fields: Serial, Scheme, Hash 330 Algorithm, and Digest. 332 A zone MAY contain multiple ZONEMD RRs to support algorithm agility 333 [RFC7696] and rollovers. Each ZONEMD RR must specify a unique Scheme 334 and Hash Algorithm tuple. It is recommended that a zone include only 335 one ZONEMD RR, unless the zone publisher is in the process of 336 transitioning to a new Scheme or Hash Algorithm. 338 2.1. Non-apex ZONEMD Records 340 This specification utilizes ZONEMD RRs located at the zone apex. 341 Non-apex ZONEMD RRs are not forbidden, but have no meaning in this 342 specification. Non-apex ZONEMD RRs MUST NOT be used for 343 verification. Non-apex ZONEMD RRSets are treated like any other 344 RRSet (which is to say they are included) during digest calculation. 346 Unless explicitly stated otherwise, "ZONEMD" always refers to apex 347 records throughout this document. 349 2.2. ZONEMD RDATA Wire Format 351 The ZONEMD RDATA wire format is encoded as follows: 353 1 1 1 1 1 1 1 1 1 1 2 2 2 2 2 2 2 2 2 2 3 3 354 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 1 355 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 356 | Serial | 357 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 358 | Scheme |Hash Algorithm | | 359 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | 360 | Digest | 361 / / 362 / / 363 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 365 2.2.1. The Serial Field 367 The Serial field is a 32-bit unsigned integer in network order. It 368 is equal to the serial number from the zone's SOA record ([RFC1035] 369 section 3.3.13) for which the zone digest was generated. 371 The zone's serial number is included here in order to make DNS 372 response messages of type ZONEMD meaningful. Without the serial 373 number, a stand-alone ZONEMD digest has no association to any 374 particular instance of a zone. 376 2.2.2. The Scheme Field 378 The Scheme field is an 8-bit unsigned integer that identifies the 379 methods by which data is collated and presented as input to the 380 hashing function. 382 At the time of this writing, SIMPLE, with value 1, is the only 383 standardized Scheme defined for ZONEMD records. The Scheme registry 384 is further described in Section 5. 386 Scheme values 240-254 are allocated for Private Use as described in 387 [RFC8126]. 389 2.2.3. The Hash Algorithm Field 391 The Hash Algorithm field is an 8-bit unsigned integer that identifies 392 the cryptographic hash algorithm used to construct the digest. 394 At the time of this writing, SHA384, with value 1, is the only 395 standardized Hash Algorithm defined for ZONEMD records. The Hash 396 Algorithm registry is further described in Section 5. 398 Hash Algorithm values 240-254 are allocated for Private Use as 399 described in [RFC8126]. 401 2.2.4. The Digest Field 403 The Digest field is a variable-length sequence of octets containing 404 the output of the hash algorithm. The Digest field must not be 405 empty. Section 3 describes how to calculate the digest for a zone. 406 Section 4 describes how to use the digest to verify the contents of a 407 zone. 409 2.3. ZONEMD Presentation Format 411 The presentation format of the RDATA portion is as follows: 413 The Serial field is represented as an unsigned decimal integer. 415 The Scheme field is represented as an unsigned decimal integer. 417 The Hash Algorithm field is represented as an unsigned decimal 418 integer. 420 The Digest is represented as a sequence of case-insensitive 421 hexadecimal digits. Whitespace is allowed within the hexadecimal 422 text. 424 2.4. ZONEMD Example 426 The following example shows a ZONEMD RR. 428 example.com. 86400 IN ZONEMD 2018031500 1 1 ( 429 FEBE3D4CE2EC2FFA4BA99D46CD69D6D29711E55217057BEE 430 7EB1A7B641A47BA7FED2DD5B97AE499FAFA4F22C6BD647DE ) 432 3. Calculating the Digest 434 3.1. Add ZONEMD Placeholder 436 In preparation for calculating the zone digest, any existing ZONEMD 437 records at the zone apex are first deleted. 439 Prior to calculation of the digest, and prior to signing with DNSSEC, 440 a placeholder ZONEMD record is added to the zone apex. This serves 441 two purposes: (1) it allows the digest to cover the Serial, Scheme, 442 and Hash Algorithm fields, and (2) ensures that appropriate denial- 443 of-existence (NSEC, NSEC3) records are created if the zone is signed 444 with DNSSEC. 446 It is recommended that the TTL of the ZONEMD record match the TTL of 447 the SOA. 449 In the placeholder record, the Serial field is set to the current SOA 450 Serial. The Scheme field is set to the value for the chosen 451 collation scheme. The Hash Algorithm field is set to the value for 452 the chosen hash algorithm. The Digest field is set to all zeroes and 453 of length appropriate for the chosen hash algorithm. 455 If multiple digests are to be published in the zone, e.g., during an 456 algorithm rollover, a placeholder record is added for each Scheme and 457 Hash Algorithm. 459 3.2. Optionally Sign the Zone 461 Following addition of placeholder records, the zone may be signed 462 with DNSSEC. Note that when the digest calculation is complete, and 463 the ZONEMD record is updated, the signature(s) for the ZONEMD RRSet 464 MUST be recalculated and updated as well. Therefore, the signer is 465 not required to calculate a signature over the placeholder record at 466 this step in the process, but it is harmless to do so. 468 3.3. Canonical Format and Ordering 470 Calculation of a zone digest REQUIRES RRs to be processed in a 471 consistent format and ordering. Correct ordering depends on (1) 472 ordering of owner names, (2) ordering of RRSets with the same owner 473 name, and (3) ordering of RRs within an RRSet. 475 This specification adopts DNSSEC's canonical ordering for names 476 (Section 6.1 of [RFC4034]), and canonical ordering for RRs within an 477 RRSet (Section 6.3 of [RFC4034]). It also adopts DNSSEC's canonical 478 RR form (Section 6.2 of [RFC4034]). However, since DNSSEC does not 479 define a canonical ordering for RRSets having the same owner name, 480 that ordering is defined here. 482 3.3.1. Order of RRSets Having the Same Owner Name 484 For the purposes of calculating the zone digest, RRSets having the 485 same owner name MUST be numerically ordered, in ascending order, by 486 their numeric RR TYPE. 488 3.4. Inclusion/Exclusion Rules 490 When iterating over records in the zone, the following inclusion/ 491 exclusion rules apply: 493 o All records in the zone, including glue records, MUST be included. 495 o Occluded data ([RFC5936] Section 3.5) MUST be included. 497 o Only one instance of duplicate RRs with equal owner, class, type 498 and RDATA SHALL be included ([RFC4034] Section 6.3). 500 o The placeholder ZONEMD RR(s) MUST be included. 502 o If the zone is signed, DNSSEC RRs MUST be included, except: 504 o The RRSIG covering ZONEMD MUST NOT be included because the RRSIG 505 will be updated after all digests have been calculated. 507 3.5. Scheme-Specific Processing 509 At this time, only the SIMPLE collation scheme is defined. 510 Additional schemes may be defined in future updates to this document. 512 3.5.1. The SIMPLE Scheme 514 For the SIMPLE scheme, the digest is calculated over the zone as a 515 whole. This means that a change to a single RR in the zone requires 516 iterating over all RRs in the zone to recalculate the digest. SIMPLE 517 is a good choice for zones that are small and/or stable, but probably 518 not good for zones that are large and/or dynamic. 520 A zone digest using the SIMPLE scheme is calculated by concatenating 521 the canonical on-the-wire form (without name compression) of all RRs 522 in the zone, in the order described in Section 3.3, subject to the 523 inclusion/exclusion rules described in Section 3.4, and then applying 524 the SHA-384 algorithm: 526 digest = hash( RR(1) | RR(2) | RR(3) | ... ) 528 where "|" denotes concatenation, and 530 RR(i) = owner | type | class | TTL | RDATA length | RDATA 532 3.6. Update ZONEMD RR 534 Once a zone digest has been calculated, its value is then copied to 535 the Digest field of the placeholder ZONEMD record. Repeat for each 536 digest if multiple digests are to be published. 538 If the zone is signed with DNSSEC, the appropriate RRSIG records 539 covering the ZONEMD RRSet MUST then be added or updated. Because the 540 ZONEMD placeholder was added prior to signing, the zone will already 541 have the appropriate denial-of-existence (NSEC, NSEC3) records. 543 Some DNSSEC implementations (especially "online signing") might be 544 designed such that the SOA serial number is updated whenever a new 545 signature is made. To preserve the calculated digest, generation of 546 an ZONEMD signature must not also result in a change to the SOA 547 serial number. The ZONEMD RR and the matching SOA MUST be published 548 at the same time. 550 4. Verifying Zone Digest 552 The recipient of a zone that has a ZONEMD RR can verify the zone by 553 calculating the digest as follows: 555 1. The verifier MUST first determine whether or not to expect 556 DNSSEC records in the zone. This can be done by examining 557 locally configured trust anchors, or querying for (and 558 validating) DS RRs in the parent zone. For zones that are 559 provably insecure, or if DNSSEC validation can not be performed, 560 digest validation continues at step 4 below. 562 2. For zones that are provably secure, the existence of the apex 563 ZONEMD record MUST be verified. If the ZONEMD record provably 564 does not exist, digest verification cannot be done. If the 565 ZONEMD record does provably exist, but is not found in the zone, 566 digest verification MUST NOT be considered successful. 568 3. For zones that are provably secure, the SOA and ZONEMD RRSets 569 MUST have valid signatures, chaining up to a trust anchor. If 570 DNSSEC validation of the SOA or ZONEMD records fails, digest 571 verification MUST NOT be considered successful. 573 4. If the ZONEMD RRSet contains more than one RR with the same 574 Scheme and Hash Algorithm, digest verification MUST NOT be 575 considered successful. 577 5. The SOA Serial field MUST exactly match the ZONEMD Serial field. 578 If the fields to not match, digest verification MUST NOT be 579 considered successful. 581 6. The ZONEMD Hash Algorithm field MUST be checked. If the 582 verifier does not support the given Hash Algorithm, it SHOULD 583 report that the zone digest could not be verified due to an 584 unsupported algorithm. 586 7. The received Digest value is copied to a temporary location. 587 Repeat for each ZONEMD RR present. 589 8. The ZONEMD RR's Digest field MUST be set to all zeroes. Repeat 590 for each RR present in the apex ZONEMD RRSet, even for 591 unsupported Scheme and Hash Algorithm values. 593 9. The zone digest is computed over the zone data as described in 594 Section 3.5. 596 10. The calculated digest is compared to the received digest stored 597 in the temporary location. If the two digest values match, 598 verification is considered successful. Otherwise, verification 599 MUST NOT be considered successful. 601 11. The ZONEMD RR's RDATA is reset to the received Digest stored in 602 the temporary location. Thus, any downstream clients can 603 similarly verify the zone. 605 4.1. Verifying Multiple Digests 607 If multiple digests are present in the zone, e.g., during an 608 algorithm rollover, a match using any one of the recipient's 609 supported Hash Algorithm algorithms is sufficient to verify the zone. 611 Note that when multiple ZONEMD RRs are present in the zone, the 612 Digest field of each MUST be zeroed in step 8 above, even for 613 unsupported Scheme and Hash Algorithm values. 615 5. IANA Considerations 617 5.1. ZONEMD RRtype 619 This document defines a new DNS RR type, ZONEMD, whose value 63 has 620 been allocated by IANA from the "Resource Record (RR) TYPEs" 621 subregistry of the "Domain Name System (DNS) Parameters" registry: 623 Type: ZONEMD 625 Value: 63 627 Meaning: Message Digest Over Zone Data 629 Reference: This document 631 5.2. ZONEMD Scheme 633 This document asks IANA to create a new "ZONEMD Scheme" registry with 634 initial contents as follows: 636 +---------+--------------------+----------+-----------+-------------+ 637 | Value | Description | Mnemonic | Status | Reference | 638 +---------+--------------------+----------+-----------+-------------+ 639 | 0 | Reserved | RESERVED | N/A | N/A | 640 | 1 | Simple ZONEMD | SIMPLE | Mandatory | This | 641 | | collation | | | document | 642 | 240-254 | Private Use | N/A | N/A | [RFC8126] | 643 +---------+--------------------+----------+-----------+-------------+ 645 Table 1: ZONEMD Scheme Registry 647 5.3. ZONEMD Hash Algorithm 649 This document asks IANA to create a new "ZONEMD Hash Algorithm" 650 registry with initial contents as follows: 652 +---------+----------------------+----------+-----------+-----------+ 653 | Value | Description | Mnemonic | Status | Reference | 654 +---------+----------------------+----------+-----------+-----------+ 655 | 0 | Reserved | RESERVED | N/A | N/A | 656 | 1 | The SHA-384 hash | SHA384 | Mandatory | [RFC6234] | 657 | | algorithm | | | | 658 | 240-254 | Private Use | N/A | N/A | [RFC8126] | 659 +---------+----------------------+----------+-----------+-----------+ 661 Table 2: ZONEMD Hash Algorithm Registry 663 6. Security Considerations 665 6.1. Attacks Against the Zone Digest 667 The zone digest allows the receiver to verify that the zone contents 668 haven't been modified since the zone was generated/published. 669 Verification is strongest when the zone is also signed with DNSSEC. 670 An attacker, whose goal is to modify zone content before it is used 671 by the victim, may consider a number of different approaches. 673 The attacker might perform a downgrade attack to an unsigned zone. 674 This is why Section 4 talks about determining whether or not to 675 expect DNSSEC signatures for the zone in step 1. 677 The attacker might perform a downgrade attack by removing one or more 678 ZONEMD records. Such a removal is detectable only with DNSSEC 679 validation and is why Section 4 talks about checking denial-of- 680 existence proofs in step 2 and signature validation in step 3. 682 The attacker might alter the Scheme, Hash Algorithm, or Digest fields 683 of the ZONEMD record. Such modifications are detectable only with 684 DNSSEC validation. 686 6.2. Attacks Utilizing the Zone Digest 688 Nothing in this specification prevents clients from making, and 689 servers from responding to, ZONEMD queries. One might consider how 690 well ZONEMD responses could be used in a distributed denial-of- 691 service amplification attack. 693 The ZONEMD RR is moderately sized, much like the DS RR. A single 694 ZONEMD RR contributes approximately 40 to 65 octets to a DNS 695 response, for currently defined digest types. Certainly other query 696 types result in larger amplification effects (i.e., DNSKEY). 698 6.3. Resilience and Fragility 700 ZONEMD can be used to detect incomplete or corrupted zone data prior 701 to its use, thereby increasing resilience, but also introducing some 702 fragility. Publishers and consumers of zones containing ZONEMD 703 records should be aware of these tradeoffs. While the intention is 704 to secure the zone data, misconfigurations or implementation bugs are 705 generally indistinguishable from intentional tampering, and could 706 lead to service failures when verification is performed 707 automatically. 709 Zone publishers may want to deploy ZONEMD gradually, perhaps by 710 utilizing one of the private use hash algorithms listed in 711 Section 5.3. Similarly, recipients may want to initially configure 712 verification failures only as a warning, and later as an error after 713 gaining experience and confidence with the feature. 715 7. Performance Considerations 717 This section is provided to make zone publishers aware of the 718 performance requirements and implications of including ZONEMD RRs in 719 a zone. 721 7.1. SIMPLE SHA384 723 As mentioned previously, the SIMPLE scheme may not be appropriate for 724 use in zones that are either large or highly dynamic. Zone 725 publishers should carefully consider the use of ZONEMD in such zones, 726 since it might cause consumers of zone data (e.g., secondary name 727 servers) to expend resources on digest calculation. Furthermore, for 728 such use cases, it is recommended that ZONEMD only be used when 729 digest calculation time is significantly less than propagation times 730 and update intervals. 732 The authors' implementation (Section 10.1) includes an option to 733 record and report CPU usage of its operation. The software was used 734 to generate digests for more than 800 TLD zones available from 735 [CZDS]. The table below summarizes the the results for the SIMPLE 736 scheme and SHA384 hash algorithm grouped by zone size. The Rate 737 column is the mean amount of time per RR to calculate the digest, 738 running on commodity hardware at the time of this writing. 740 +---------------------+----------------+ 741 | Zone Size (RRs) | Rate (msec/RR) | 742 +---------------------+----------------+ 743 | 10 - 99 | 0.00683 | 744 | 100 - 999 | 0.00551 | 745 | 1000 - 9999 | 0.00505 | 746 | 10000 - 99999 | 0.00602 | 747 | 100000 - 999999 | 0.00845 | 748 | 1000000 - 9999999 | 0.0108 | 749 | 10000000 - 99999999 | 0.0148 | 750 +---------------------+----------------+ 752 For example, based on the above table, it takes approximately 0.13 753 seconds to calculate a SIMPLE SHA384 digest for a zone with 22,000 754 RRs, and about 2.5 seconds for a zone with 300,000 RRs. 756 8. Privacy Considerations 758 This specification has no impacts on user privacy. 760 9. Acknowledgments 762 The authors wish to thank David Blacka, Scott Hollenbeck, and Rick 763 Wilhelm for providing feedback on early drafts of this document. 764 Additionally, they thank Joe Abley, Mark Andrews, Ralph Dolmans, 765 Richard Gibson, Olafur Gudmundsson, Bob Harold, Paul Hoffman, Evan 766 Hunt, Shumon Huque, Tatuya Jinmei, Mike St. Johns, Burt Kaliski, 767 Shane Kerr, Matt Larson, John Levine, Ed Lewis, Matt Pounsett, Mukund 768 Sivaraman, Petr Spacek, Ondrej Sury, Willem Toorop, Florian Weimer, 769 Tim Wicinksi, Wouter Wijngarrds, Paul Wouters, and other members of 770 the dnsop working group for their input. 772 10. Implementation Status 774 10.1. Authors' Implementation 776 The authors have an open source implementation in C, using the ldns 777 library [ldns-zone-digest]. This implementation is able to perform 778 the following functions: 780 o Read an input zone and output a zone with the ZONEMD placeholder. 782 o Compute zone digest over signed zone and update the ZONEMD record. 784 o Re-compute DNSSEC signature over the ZONEMD record. 786 o Verify the zone digest from an input zone. 788 This implementation does not: 790 o Perform DNSSEC validation of the ZONEMD record during 791 verification. 793 10.2. Shane Kerr's Implementation 795 Shane Kerr wrote an implementation of this specification during the 796 IETF 102 hackathon [ZoneDigestHackathon]. This implementation is in 797 Python and is able to perform the following functions: 799 o Read an input zone and output a zone with ZONEMD record. 801 o Verify the zone digest from an input zone. 803 o Output the ZONEMD record in its defined presentation format. 805 This implementation does not: 807 o Re-compute DNSSEC signature over the ZONEMD record. 809 o Perform DNSSEC validation of the ZONEMD record. 811 11. Change Log 813 RFC Editor: Please remove this section. 815 This section lists substantial changes to the document as it is being 816 worked on. 818 From -00 to -01: 820 o Removed requirement to sort by RR CLASS. 822 o Added Kumari and Hardaker as coauthors. 824 o Added Change Log section. 826 o Minor clarifications and grammatical edits. 828 From -01 to -02: 830 o Emphasize desire for data security over channel security. 832 o Expanded motivation into its own subsection. 834 o Removed discussion topic whether or not to include serial in 835 ZONEMD. 837 o Clarified that a zone's NS records always sort before the SOA 838 record. 840 o Clarified that all records in the zone must are digested, except 841 as specified in the exclusion rules. 843 o Added for discussion out-of-zone and occluded records. 845 o Clarified that update of ZONEMD signature must not cause a serial 846 number change. 848 o Added persons to acknowledgments. 850 From -02 to -03: 852 o Added recommendation to set ZONEMD TTL to SOA TTL. 854 o Clarified that digest input uses uncompressed names. 856 o Updated Implementations section. 858 o Changed intended status from Standards Track to Experimental and 859 added Scope of Experiment section. 861 o Updated Motivation, Introduction, and Design Overview sections in 862 response to working group discussion. 864 o Gave ZONEMD digest types their own status, separate from DS digest 865 types. Request IANA to create a registry. 867 o Added Reserved field for future work supporting dynamic updates. 869 o Be more rigorous about having just ONE ZONEMD record in the zone. 871 o Expanded use cases. 873 From -03 to -04: 875 o Added an appendix with example zones and digests. 877 o Clarified that only apex ZONEMD RRs shall be processed. 879 From -04 to -05: 881 o Made SHA384 the only supported ZONEMD digest type. 883 o Disassociated ZONEMD digest types from DS digest types. 885 o Updates to Introduction based on list feedback. 887 o Changed "zone file" to "zone" everywhere. 889 o Restored text about why ZONEMD has a Serial field. 891 o Clarified ordering of RRSets having same owner to be numerically 892 ascending. 894 o Clarified that all duplicate RRs (not just SOA) must be suppressed 895 in digest calculation. 897 o Clarified that the Reserved field must be set to zero and checked 898 for zero in verification. 900 o Clarified that occluded data must be included. 902 o Clarified procedure for verification, using temporary location for 903 received digest. 905 o Explained why Reserved field is 8-bits. 907 o IANA Considerations section now more specific. 909 o Added complex zone to examples. 911 o 913 From -05 to -06: 915 o RR type code 63 was assigned to ZONEMD by IANA. 917 From -06 to -07: 919 o Fixed mistakes in ZONEMD examples. 921 o Added private use Digest Type values 240-254. 923 o Clarified that Digest field must not be empty. 925 From -07 to draft-ietf-dnsop-dns-zone-digest-00: 927 o Adopted by dnsop. 929 o Clarified further that non-apex ZONEMD RRs have no meaning. 931 o Changed "provably [un]signed" to "provably [in]secure". 933 o Allow multiple ZONEMD RRs to support algorithm agility/rollovers. 935 o Describe verification when there are multiple ZONEMD RRs. 937 From -00 to -01: 939 o Simplified requirements around verifying multiple digests. Any 940 one match is sufficient. 942 o Updated implementation notes. 944 o Both implementations produce expected results on examples given in 945 this document. 947 From -01 to -02: 949 o Changed the name of the Reserved field to Parameter. 951 o Changed the name of Digest Type 1 from SHA384 to SHA384-STABLE. 953 o The meaning of the Parameter field now depends on Digest Type. 955 o No longer require Parameter field to be zero in verification. 957 o Updated a rule from earlier versions that said multiple ZONEMD RRs 958 were not allowed. 960 From -02 to -03: 962 o Changed the name of Digest Type 1 from SHA384-STABLE to 963 SHA384-SIMPLE. 965 o Changed document status from Experimental to Standards Track. 967 o Removed Scope of Experimentation section. 969 From -03 to -04: 971 o Addressing WGLC feedback. 973 o Changed from "Digest Type + Paramter" to "Scheme + Hash 974 Algorithm". This should make it more obvious how ZONEMD can be 975 expanded in the future with new schemes and hash algorithms, while 976 sacrificing some of the flexibility that the Parameter was 977 intended to provide. 979 o Note: old RDATA fields: Serial, Digest Type, Parameter, Digest. 981 o Note: new RDATA fields: Serial, Scheme, Hash Algorithm, Digest. 983 o Add new IANA requirement for a Scheme registry. 985 o Rearranged some sections and separated scheme-specific aspects 986 from general aspects of digest calculation. 988 o When discussing multiple ZONEMD RRs, allow for Scheme, as well as 989 Hash Algorithm, transition. 991 o Added Performance Considerations section with some benchmarks. 993 o Further clarifications about non-apex ZONEMD RRs. 995 o Clarified inclusion rule for duplicate RRs. 997 o Removed or lowercased some inappropriately used RFC 2119 key 998 words. 1000 o Clarified that all ZONEMD RRs, even for unsupported hash 1001 algorithms, must be zeroized during digest calculation. 1003 o Added Resilience and Fragility to security considerations. 1005 o Updated examples since changes in this version result in different 1006 hash values. 1008 12. References 1010 12.1. Normative References 1012 [RFC1034] Mockapetris, P., "Domain names - concepts and facilities", 1013 STD 13, RFC 1034, DOI 10.17487/RFC1034, November 1987, 1014 . 1016 [RFC1035] Mockapetris, P., "Domain names - implementation and 1017 specification", STD 13, RFC 1035, DOI 10.17487/RFC1035, 1018 November 1987, . 1020 [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate 1021 Requirement Levels", BCP 14, RFC 2119, 1022 DOI 10.17487/RFC2119, March 1997, 1023 . 1025 [RFC2181] Elz, R. and R. Bush, "Clarifications to the DNS 1026 Specification", RFC 2181, DOI 10.17487/RFC2181, July 1997, 1027 . 1029 [RFC4034] Arends, R., Austein, R., Larson, M., Massey, D., and S. 1030 Rose, "Resource Records for the DNS Security Extensions", 1031 RFC 4034, DOI 10.17487/RFC4034, March 2005, 1032 . 1034 [RFC6234] Eastlake 3rd, D. and T. Hansen, "US Secure Hash Algorithms 1035 (SHA and SHA-based HMAC and HKDF)", RFC 6234, 1036 DOI 10.17487/RFC6234, May 2011, 1037 . 1039 [RFC8174] Leiba, B., "Ambiguity of Uppercase vs Lowercase in RFC 1040 2119 Key Words", BCP 14, RFC 8174, DOI 10.17487/RFC8174, 1041 May 2017, . 1043 12.2. Informative References 1045 [CZDS] Internet Corporation for Assigned Names and Numbers, 1046 "Centralized Zone Data Service", October 2018, 1047 . 1049 [dns-over-https] 1050 Hoffman, P. and P. McManus, "DNS Queries over HTTPS 1051 (DoH)", draft-ietf-doh-dns-over-https-12 (work in 1052 progress), June 2018, . 1055 [InterNIC] 1056 ICANN, "InterNIC FTP site", May 2018, 1057 . 1059 [ldns-zone-digest] 1060 Verisign, "Implementation of Message Digests for DNS Zones 1061 using the ldns library", July 2018, 1062 . 1064 [RFC1995] Ohta, M., "Incremental Zone Transfer in DNS", RFC 1995, 1065 DOI 10.17487/RFC1995, August 1996, 1066 . 1068 [RFC2065] Eastlake 3rd, D. and C. Kaufman, "Domain Name System 1069 Security Extensions", RFC 2065, DOI 10.17487/RFC2065, 1070 January 1997, . 1072 [RFC2136] Vixie, P., Ed., Thomson, S., Rekhter, Y., and J. Bound, 1073 "Dynamic Updates in the Domain Name System (DNS UPDATE)", 1074 RFC 2136, DOI 10.17487/RFC2136, April 1997, 1075 . 1077 [RFC2535] Eastlake 3rd, D., "Domain Name System Security 1078 Extensions", RFC 2535, DOI 10.17487/RFC2535, March 1999, 1079 . 1081 [RFC2845] Vixie, P., Gudmundsson, O., Eastlake 3rd, D., and B. 1082 Wellington, "Secret Key Transaction Authentication for DNS 1083 (TSIG)", RFC 2845, DOI 10.17487/RFC2845, May 2000, 1084 . 1086 [RFC2931] Eastlake 3rd, D., "DNS Request and Transaction Signatures 1087 ( SIG(0)s )", RFC 2931, DOI 10.17487/RFC2931, September 1088 2000, . 1090 [RFC3851] Ramsdell, B., Ed., "Secure/Multipurpose Internet Mail 1091 Extensions (S/MIME) Version 3.1 Message Specification", 1092 RFC 3851, DOI 10.17487/RFC3851, July 2004, 1093 . 1095 [RFC4880] Callas, J., Donnerhacke, L., Finney, H., Shaw, D., and R. 1096 Thayer, "OpenPGP Message Format", RFC 4880, 1097 DOI 10.17487/RFC4880, November 2007, 1098 . 1100 [RFC5936] Lewis, E. and A. Hoenes, Ed., "DNS Zone Transfer Protocol 1101 (AXFR)", RFC 5936, DOI 10.17487/RFC5936, June 2010, 1102 . 1104 [RFC7696] Housley, R., "Guidelines for Cryptographic Algorithm 1105 Agility and Selecting Mandatory-to-Implement Algorithms", 1106 BCP 201, RFC 7696, DOI 10.17487/RFC7696, November 2015, 1107 . 1109 [RFC7706] Kumari, W. and P. Hoffman, "Decreasing Access Time to Root 1110 Servers by Running One on Loopback", RFC 7706, 1111 DOI 10.17487/RFC7706, November 2015, 1112 . 1114 [RFC7719] Hoffman, P., Sullivan, A., and K. Fujiwara, "DNS 1115 Terminology", RFC 7719, DOI 10.17487/RFC7719, December 1116 2015, . 1118 [RFC7858] Hu, Z., Zhu, L., Heidemann, J., Mankin, A., Wessels, D., 1119 and P. Hoffman, "Specification for DNS over Transport 1120 Layer Security (TLS)", RFC 7858, DOI 10.17487/RFC7858, May 1121 2016, . 1123 [RFC8126] Cotton, M., Leiba, B., and T. Narten, "Guidelines for 1124 Writing an IANA Considerations Section in RFCs", BCP 26, 1125 RFC 8126, DOI 10.17487/RFC8126, June 2017, 1126 . 1128 [RootServers] 1129 Root Server Operators, "Root Server Technical Operations", 1130 July 2018, . 1132 [RPZ] Vixie, P. and V. Schryver, "DNS Response Policy Zones 1133 (RPZ)", draft-vixie-dnsop-dns-rpz-00 (work in progress), 1134 June 2018, . 1137 [ZoneDigestHackathon] 1138 Kerr, S., "Prototype implementation of ZONEMD for the IETF 1139 102 hackathon in Python", July 2018, 1140 . 1142 Appendix A. Example Zones With Digests 1144 This appendix contains example zones with accurate ZONEMD records. 1145 These can be used to verify an implementation of the zone digest 1146 protocol. 1148 A.1. Simple EXAMPLE Zone 1150 Here, the EXAMPLE zone contains an SOA record, NS and glue records, 1151 and a ZONEMD record. 1153 example. 86400 IN SOA ns1 admin 2018031900 ( 1154 1800 900 604800 86400 ) 1155 86400 IN NS ns1 1156 86400 IN NS ns2 1157 86400 IN ZONEMD 2018031900 1 1 ( 1158 b3437dca3d6c9047 1159 9f43d4bf0c1a805e 1160 fbfca88635df014f 1161 04a1049368a23a77 1162 577d896f0c58c5c7 1163 338aabc7aa4314b5 ) 1164 ns1 3600 IN A 127.0.0.1 1165 ns2 3600 IN AAAA ::1 1167 A.2. Complex EXAMPLE Zone 1169 Here, the EXAMPLE zone contains duplicate RRs, and an occluded RR, 1170 and one out-of-zone RR. 1172 example. 86400 IN SOA ns1 admin 2018031900 ( 1173 1800 900 604800 86400 ) 1174 86400 IN NS ns1 1175 86400 IN NS ns2 1176 86400 IN ZONEMD 2018031900 1 1 ( 1177 9c31e37bd2d97ad4 1178 9ead67b3a44f267e 1179 a223cc70c1a0988d 1180 49ac98da1b7ca1ed 1181 ede57661b6cefc52 1182 80d10d6b4b0b6cb1 ) 1183 ns1 3600 IN A 127.0.0.1 1184 ns2 3600 IN AAAA ::1 1185 occluded.sub 7200 IN TXT "I'm occluded but must be digested" 1186 sub 7200 IN NS ns1 1187 duplicate 300 IN TXT "I must be digested just once" 1188 duplicate 300 IN TXT "I must be digested just once" 1189 foo.test. 555 IN TXT "out-of-zone data must be excluded" 1190 non-apex 900 IN ZONEMD 2018031900 1 1 ( 1191 616c6c6f77656420 1192 6275742069676e6f 1193 7265642e20616c6c 1194 6f77656420627574 1195 2069676e6f726564 1196 2e20616c6c6f7765 ) 1198 A.3. EXAMPLE Zone with multiple digests 1200 Here, the EXAMPLE zone contains multiple ZONEMD records. Since only 1201 one Hash Algorithm is defined at this time (SHA384), this example 1202 utilizes additional ZONEMD records with Hash Algorithm values in the 1203 private range (240-254). These additional private-range digests are 1204 not verifiable, but note that their other fields (Serial, Scheme, 1205 Hash Algorithm) are included in the calculation of all ZONEMD 1206 digests. 1208 example. 86400 IN SOA ns1 admin 2018031900 ( 1209 1800 900 604800 86400 ) 1210 example. 86400 IN NS ns1.example. 1211 example. 86400 IN NS ns2.example. 1212 example. 86400 IN ZONEMD 2018031900 1 1 ( 1213 6a126e222407923d 1214 f70e7aa44d5e813b 1215 0b18b469b78d3d50 1216 84cd3cbf24152eea 1217 a68c00b6536bba2a 1218 1f2cab0fd03a8162 ) 1219 example. 86400 IN ZONEMD 2018031900 1 240 ( 1220 e2d523f654b9422a 1221 96c5a8f44607bbee ) 1222 example. 86400 IN ZONEMD 2018031900 1 241 ( 1223 5732dd91240611f8 1224 314adb6b4769bdd2 ) 1225 example. 86400 IN ZONEMD 2018031900 1 242 ( 1226 7c32e06779315c7d 1227 81ba8c72f5cf9116 1228 496b6395 ) 1229 example. 86400 IN ZONEMD 2018031900 1 243 ( 1230 183770af4a629f80 1231 2e674e305b8d0d11 1232 3dfe0837 ) 1233 example. 86400 IN ZONEMD 2018031900 1 244 ( 1234 e1846540e33a9e41 1235 89792d18d5d131f6 1236 05fc283e ) 1237 example. 86400 IN ZONEMD 2018031900 240 1 ( 1238 e1846540e33a9e41 1239 89792d18d5d131f6 1240 05fc283e ) 1241 ns1.example. 3600 IN A 127.0.0.1 1242 ns2.example. 86400 IN TXT "This example has multiple digests" 1243 ns2.example. 3600 IN AAAA ::1 1245 A.4. The URI.ARPA Zone 1247 The URI.ARPA zone retrieved 2018-10-21. Note this sample zone has 1248 (expired) signatures, but no signature for the ZONEMD RR. 1250 ; <<>> DiG 9.9.4 <<>> @lax.xfr.dns.icann.org uri.arpa axfr 1251 ; (2 servers found) 1252 ;; global options: +cmd 1253 uri.arpa. 3600 IN SOA sns.dns.icann.org. ( 1254 noc.dns.icann.org. 2018100702 10800 3600 1209600 3600 ) 1255 uri.arpa. 3600 IN RRSIG NSEC 8 2 3600 ( 1256 20181028142623 20181007205525 47155 uri.arpa. 1257 eEC4w/oXLR1Epwgv4MBiDtSBsXhqrJVvJWUpbX8XpetAvD35bxwNCUTi 1258 /pAJVUXefegWeiriD2rkTgCBCMmn7YQIm3gdR+HjY/+o3BXNQnz97f+e 1259 HAE9EDDzoNVfL1PyV/2fde9tDeUuAGVVwmD399NGq9jWYMRpyri2kysr q/g= ) 1260 uri.arpa. 86400 IN RRSIG NS 8 2 86400 ( 1261 20181028172020 20181007175821 47155 uri.arpa. 1262 ATyV2A2A8ZoggC+68u4GuP5MOUuR+2rr3eWOkEU55zAHld/7FiBxl4ln 1263 4byJYy7NudUwlMOEXajqFZE7DVl8PpcvrP3HeeGaVzKqaWj+aus0jbKF 1264 Bsvs2b1qDZemBfkz/IfAhUTJKnto0vSUicJKfItu0GjyYNJCz2CqEuGD Wxc= ) 1265 uri.arpa. 600 IN RRSIG MX 8 2 600 ( 1266 20181028170556 20181007175821 47155 uri.arpa. 1267 e7/r3KXDohX1lyVavetFFObp8fB8aXT76HnN9KCQDxSnSghNM83UQV0t 1268 lTtD8JVeN1mCvcNFZpagwIgB7XhTtm6Beur/m5ES+4uSnVeS6Q66HBZK 1269 A3mR95IpevuVIZvvJ+GcCAQpBo6KRODYvJ/c/ZG6sfYWkZ7qg/Em5/+3 4UI= ) 1270 uri.arpa. 3600 IN RRSIG DNSKEY 8 2 3600 ( 1271 20181028152832 20181007175821 15796 uri.arpa. 1272 nzpbnh0OqsgBBP8St28pLvPEQ3wZAUdEBuUwil+rtjjWlYYiqjPxZ286 1273 XF4Rq1usfV5x71jZz5IqswOaQgia91ylodFpLuXD6FTGs2nXGhNKkg1V 1274 chHgtwj70mXU72GefVgo8TxrFYzxuEFP5ZTP92t97FVWVVyyFd86sbbR 1275 6DZj3uA2wEvqBVLECgJLrMQ9Yy7MueJl3UA4h4E6zO2JY9Yp0W9woq0B 1276 dqkkwYTwzogyYffPmGAJG91RJ2h6cHtFjEZe2MnaY2glqniZ0WT9vXXd 1277 uFPm0KD9U77Ac+ZtctAF9tsZwSdAoL365E2L1usZbA+K0BnPPqGFJRJk 1278 5R0A1w== ) 1279 uri.arpa. 3600 IN RRSIG DNSKEY 8 2 3600 ( 1280 20181028152832 20181007175821 55480 uri.arpa. 1281 lWtQV/5szQjkXmbcD47/+rOW8kJPksRFHlzxxmzt906+DBYyfrH6uq5X 1282 nHvrUlQO6M12uhqDeL+bDFVgqSpNy+42/OaZvaK3J8EzPZVBHPJykKMV 1283 63T83aAiJrAyHzOaEdmzLCpalqcEE2ImzlLHSafManRfJL8Yuv+JDZFj 1284 2WDWfEcUuwkmIZWX11zxp+DxwzyUlRl7x4+ok5iKZWIg5UnBAf6B8T75 1285 WnXzlhCw3F2pXI0a5LYg71L3Tp/xhjN6Yy9jGlIRf5BjB59X2zra3a2R 1286 PkI09SSnuEwHyF1mDaV5BmQrLGRnCjvwXA7ho2m+vv4SP5dUdXf+GTeA 1287 1HeBfw== ) 1288 uri.arpa. 3600 IN RRSIG SOA 8 2 3600 ( 1289 20181029114753 20181008222815 47155 uri.arpa. 1290 qn8yBNoHDjGdT79U2Wu9IIahoS0YPOgYP8lG+qwPcrZ1BwGiHywuoUa2 1291 Mx6BWZlg+HDyaxj2iOmox+IIqoUHhXUbO7IUkJFlgrOKCgAR2twDHrXu 1292 9BUQHy9SoV16wYm3kBTEPyxW5FFm8vcdnKAF7sxSY8BbaYNpRIEjDx4A JUc= ) 1293 uri.arpa. 3600 IN NSEC ftp.uri.arpa. NS SOA ( 1294 MX RRSIG NSEC DNSKEY ) 1295 uri.arpa. 86400 IN NS a.iana-servers.net. 1296 uri.arpa. 86400 IN NS b.iana-servers.net. 1297 uri.arpa. 86400 IN NS c.iana-servers.net. 1298 uri.arpa. 86400 IN NS ns2.lacnic.net. 1299 uri.arpa. 86400 IN NS sec3.apnic.net. 1300 uri.arpa. 600 IN MX 10 pechora.icann.org. 1301 uri.arpa. 3600 IN DNSKEY 256 3 8 ( 1302 AwEAAcBi7tSart2J599zbYWspMNGN70IBWb4ziqyQYH9MTB/VCz6WyUK 1303 uXunwiJJbbQ3bcLqTLWEw134B6cTMHrZpjTAb5WAwg4XcWUu8mdcPTiL 1304 Bl6qVRlRD0WiFCTzuYUfkwsh1Rbr7rvrxSQhF5rh71zSpwV5jjjp65Wx 1305 SdJjlH0B ) 1306 uri.arpa. 3600 IN DNSKEY 257 3 8 ( 1307 AwEAAbNVv6ulgRdO31MtAehz7j3ALRjwZglWesnzvllQl/+hBRZr9QoY 1308 cO2I+DkO4Q1NKxox4DUIxj8SxPO3GwDuOFR9q2/CFi2O0mZjafbdYtWc 1309 3zSdBbi3q0cwCIx7GuG9eqlL+pg7mdk9dgdNZfHwB0LnqTD8ebLPsrO/ 1310 Id7kBaiqYOfMlZnh2fp+2h6OOJZHtY0DK1UlssyB5PKsE0tVzo5s6zo9 1311 iXKe5u+8WTMaGDY49vG80JPAKE7ezMiH/NZcUMiE0PRZ8D3foq2dYuS5 1312 ym+vA83Z7v8A+Rwh4UGnjxKB8zmr803V0ASAmHz/gwH5Vb0nH+LObwFt 1313 l3wpbp+Wpm8= ) 1314 uri.arpa. 3600 IN DNSKEY 257 3 8 ( 1315 AwEAAbwnFTakCvaUKsXji4mgmxZUJi1IygbnGahbkmFEa0L16J+TchKR 1316 wcgzVfsxUGa2MmeA4hgkAooC3uy+tTmoMsgy8uq/JAj24DjiHzd46LfD 1317 FK/qMidVqFpYSHeq2Vv5ojkuIsx4oe4KsafGWYNOczKZgH5loGjN2aJG 1318 mrIm++XCphOskgCsQYl65MIzuXffzJyxlAuts+ecAIiVeqRaqQfr8LRU 1319 7wIsLxinXirprtQrbor+EtvlHp9qXE6ARTZDzf4jvsNpKvLFZtmxzFf3 1320 e/UJz5eHjpwDSiZL7xE8aE1o1nGfPtJx9ZnB3bapltaJ5wY+5XOCKgY0 1321 xmJVvNQlwdE= ) 1322 ftp.uri.arpa. 3600 IN RRSIG NSEC 8 3 3600 ( 1323 20181028080856 20181007175821 47155 uri.arpa. 1324 HClGAqPxzkYkAT7Q/QNtQeB6YrkP6EPOef+9Qo5/2zngwAewXEAQiyF9 1325 jD1USJiroM11QqBS3v3aIdW/LXORs4Ez3hLcKNO1cKHsOuWAqzmE+BPP 1326 Arfh8N95jqh/q6vpaB9UtMkQ53tM2fYU1GszOLN0knxbHgDHAh2axMGH lqM= ) 1327 ftp.uri.arpa. 604800 IN RRSIG NAPTR 8 3 604800 ( 1328 20181028103644 20181007205525 47155 uri.arpa. 1329 WoLi+vZzkxaoLr2IGZnwkRvcDf6KxiWQd1WZP/U+AWnV+7MiqsWPZaf0 1330 9toRErerGoFOiOASNxZjBGJrRgjmavOM9U+LZSconP9zrNFd4dIu6kp5 1331 YxlQJ0uHOvx1ZHFCj6lAt1ACUIw04ZhMydTmi27c8MzEOMepvn7iH7r7 k7k= ) 1332 ftp.uri.arpa. 3600 IN NSEC http.uri.arpa. NAPTR ( 1333 RRSIG NSEC ) 1334 ftp.uri.arpa. 604800 IN NAPTR 0 0 "" "" ( 1335 "!^ftp://([^:/?#]*).*$!\\1!i" . ) 1336 http.uri.arpa. 3600 IN RRSIG NSEC 8 3 3600 ( 1337 20181029010647 20181007175821 47155 uri.arpa. 1338 U03NntQ73LHWpfLmUK8nMsqkwVsOGW2KdsyuHYAjqQSZvKbtmbv7HBmE 1339 H1+Ii3Z+wtfdMZBy5aC/6sHdx69BfZJs16xumycMlAy6325DKTQbIMN+ 1340 ift9GrKBC7cgCd2msF/uzSrYxxg4MJQzBPvlkwXnY3b7eJSlIXisBIn7 3b8= ) 1341 http.uri.arpa. 604800 IN RRSIG NAPTR 8 3 604800 ( 1342 20181029011815 20181007205525 47155 uri.arpa. 1343 T7mRrdag+WSmG+n22mtBSQ/0Y3v+rdDnfQV90LN5Fq32N5K2iYFajF7F 1344 Tp56oOznytfcL4fHrqOE0wRc9NWOCCUec9C7Wa1gJQcllEvgoAM+L6f0 1345 RsEjWq6+9jvlLKMXQv0xQuMX17338uoD/xiAFQSnDbiQKxwWMqVAimv5 7Zs= ) 1346 http.uri.arpa. 3600 IN NSEC mailto.uri.arpa. NAPTR ( 1347 RRSIG NSEC ) 1348 http.uri.arpa. 604800 IN NAPTR 0 0 "" "" ( 1349 "!^http://([^:/?#]*).*$!\\1!i" . ) 1350 mailto.uri.arpa. 3600 IN RRSIG NSEC 8 3 3600 ( 1351 20181028110727 20181007175821 47155 uri.arpa. 1353 GvxzVL85rEukwGqtuLxek9ipwjBMfTOFIEyJ7afC8HxVMs6mfFa/nEM/ 1354 IdFvvFg+lcYoJSQYuSAVYFl3xPbgrxVSLK125QutCFMdC/YjuZEnq5cl 1355 fQciMRD7R3+znZfm8d8u/snLV9w4D+lTBZrJJUBe1Efc8vum5vvV7819 ZoY= ) 1356 mailto.uri.arpa. 604800 IN RRSIG NAPTR 8 3 604800 ( 1357 20181028141825 20181007205525 47155 uri.arpa. 1358 MaADUgc3fc5v++M0YmqjGk3jBdfIA5RuP62hUSlPsFZO4k37erjIGCfF 1359 j+g84yc+QgbSde0PQHszl9fE/+SU5ZXiS9YdcbzSZxp2erFpZOTchrpg 1360 916T4vx6i59scodjb0l6bDyZ+mtIPrc1w6b4hUyOUTsDQoAJYxdfEuMg Vy4= ) 1361 mailto.uri.arpa. 3600 IN NSEC urn.uri.arpa. NAPTR ( 1362 RRSIG NSEC ) 1363 mailto.uri.arpa. 604800 IN NAPTR 0 0 "" "" ( 1364 "!^mailto:(.*)@(.*)$!\\2!i" . ) 1365 urn.uri.arpa. 3600 IN RRSIG NSEC 8 3 3600 ( 1366 20181028123243 20181007175821 47155 uri.arpa. 1367 Hgsw4Deops1O8uWyELGe6hpR/OEqCnTHvahlwiQkHhO5CSEQrbhmFAWe 1368 UOkmGAdTEYrSz+skLRQuITRMwzyFf4oUkZihGyhZyzHbcxWfuDc/Pd/9 1369 DSl56gdeBwy1evn5wBTms8yWQVkNtphbJH395gRqZuaJs3LD/qTyJ5Dp LvA= ) 1370 urn.uri.arpa. 604800 IN RRSIG NAPTR 8 3 604800 ( 1371 20181029071816 20181007205525 47155 uri.arpa. 1372 ALIZD0vBqAQQt40GQ0Efaj8OCyE9xSRJRdyvyn/H/wZVXFRFKrQYrLAS 1373 D/K7q6CMTOxTRCu2J8yes63WJiaJEdnh+dscXzZkmOg4n5PsgZbkvUSW 1374 BiGtxvz5jNncM0xVbkjbtByrvJQAO1cU1mnlDKe1FmVB1uLpVdA9Ib4J hMU= ) 1375 urn.uri.arpa. 3600 IN NSEC uri.arpa. NAPTR RRSIG ( 1376 NSEC ) 1377 urn.uri.arpa. 604800 IN NAPTR 0 0 "" "" ( 1378 "/urn:([^:]+)/\\1/i" . ) 1379 uri.arpa. 3600 IN SOA sns.dns.icann.org. ( 1380 noc.dns.icann.org. 2018100702 10800 3600 1209600 3600 ) 1381 ;; Query time: 66 msec 1382 ;; SERVER: 192.0.32.132#53(192.0.32.132) 1383 ;; WHEN: Sun Oct 21 20:39:28 UTC 2018 1384 ;; XFR size: 34 records (messages 1, bytes 3941) 1385 uri.arpa. 3600 IN ZONEMD 2018100702 1 1 ( 1386 cc4a0b6556272fc739b8ff74b80b4a43ac9575d91445ecc0dc22f5 1387 09fa27c62448a7100660bbdb4c90667424b734956b ) 1389 A.5. The ROOT-SERVERS.NET Zone 1391 The ROOT-SERVERS.NET zone retreived 2018-10-21. 1393 root-servers.net. 3600000 IN SOA a.root-servers.net. ( 1394 nstld.verisign-grs.com. 2018091100 14400 7200 1209600 3600000 ) 1395 root-servers.net. 3600000 IN NS a.root-servers.net. 1396 root-servers.net. 3600000 IN NS b.root-servers.net. 1397 root-servers.net. 3600000 IN NS c.root-servers.net. 1398 root-servers.net. 3600000 IN NS d.root-servers.net. 1399 root-servers.net. 3600000 IN NS e.root-servers.net. 1400 root-servers.net. 3600000 IN NS f.root-servers.net. 1401 root-servers.net. 3600000 IN NS g.root-servers.net. 1402 root-servers.net. 3600000 IN NS h.root-servers.net. 1403 root-servers.net. 3600000 IN NS i.root-servers.net. 1404 root-servers.net. 3600000 IN NS j.root-servers.net. 1405 root-servers.net. 3600000 IN NS k.root-servers.net. 1406 root-servers.net. 3600000 IN NS l.root-servers.net. 1407 root-servers.net. 3600000 IN NS m.root-servers.net. 1408 a.root-servers.net. 3600000 IN AAAA 2001:503:ba3e::2:30 1409 a.root-servers.net. 3600000 IN A 198.41.0.4 1410 b.root-servers.net. 3600000 IN MX 20 mail.isi.edu. 1411 b.root-servers.net. 3600000 IN AAAA 2001:500:200::b 1412 b.root-servers.net. 3600000 IN A 199.9.14.201 1413 c.root-servers.net. 3600000 IN AAAA 2001:500:2::c 1414 c.root-servers.net. 3600000 IN A 192.33.4.12 1415 d.root-servers.net. 3600000 IN AAAA 2001:500:2d::d 1416 d.root-servers.net. 3600000 IN A 199.7.91.13 1417 e.root-servers.net. 3600000 IN AAAA 2001:500:a8::e 1418 e.root-servers.net. 3600000 IN A 192.203.230.10 1419 f.root-servers.net. 3600000 IN AAAA 2001:500:2f::f 1420 f.root-servers.net. 3600000 IN A 192.5.5.241 1421 g.root-servers.net. 3600000 IN AAAA 2001:500:12::d0d 1422 g.root-servers.net. 3600000 IN A 192.112.36.4 1423 h.root-servers.net. 3600000 IN AAAA 2001:500:1::53 1424 h.root-servers.net. 3600000 IN A 198.97.190.53 1425 i.root-servers.net. 3600000 IN MX 10 mx.i.root-servers.org. 1426 i.root-servers.net. 3600000 IN AAAA 2001:7fe::53 1427 i.root-servers.net. 3600000 IN A 192.36.148.17 1428 j.root-servers.net. 3600000 IN AAAA 2001:503:c27::2:30 1429 j.root-servers.net. 3600000 IN A 192.58.128.30 1430 k.root-servers.net. 3600000 IN AAAA 2001:7fd::1 1431 k.root-servers.net. 3600000 IN A 193.0.14.129 1432 l.root-servers.net. 3600000 IN AAAA 2001:500:9f::42 1433 l.root-servers.net. 3600000 IN A 199.7.83.42 1434 m.root-servers.net. 3600000 IN AAAA 2001:dc3::35 1435 m.root-servers.net. 3600000 IN A 202.12.27.33 1436 root-servers.net. 3600000 IN SOA a.root-servers.net. ( 1437 nstld.verisign-grs.com. 2018091100 14400 7200 1209600 3600000 ) 1438 root-servers.net. 3600000 IN ZONEMD 2018091100 1 1 ( 1439 4fb752b314e4dccb845832b611590b669a80daebb736d4bd22aa76ec06 1440 6737c79185c1f7dfd49ec91d9523e6240ea2c4 ) 1442 Authors' Addresses 1444 Duane Wessels 1445 Verisign 1446 12061 Bluemont Way 1447 Reston, VA 20190 1449 Phone: +1 703 948-3200 1450 Email: dwessels@verisign.com 1451 URI: http://verisign.com 1453 Piet Barber 1454 Verisign 1455 12061 Bluemont Way 1456 Reston, VA 20190 1458 Phone: +1 703 948-3200 1459 Email: pbarber@verisign.com 1460 URI: http://verisign.com 1462 Matt Weinberg 1463 Verisign 1464 12061 Bluemont Way 1465 Reston, VA 20190 1467 Phone: +1 703 948-3200 1468 Email: mweinberg@verisign.com 1469 URI: http://verisign.com 1471 Warren Kumari 1472 Google 1473 1600 Amphitheatre Parkway 1474 Mountain View, CA 94043 1476 Email: warren@kumari.net 1478 Wes Hardaker 1479 USC/ISI 1480 P.O. Box 382 1481 Davis, CA 95617 1483 Email: ietf@hardakers.net