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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: April 12, 2021 M. Weinberg 6 Amazon 7 W. Kumari 8 Google 9 W. Hardaker 10 USC/ISI 11 October 9, 2020 13 Message Digest for DNS Zones 14 draft-ietf-dnsop-dns-zone-digest-13 16 Abstract 18 This document describes a protocol and new DNS Resource Record that 19 provides a cryptographic message digest over DNS zone data at rest. 20 The ZONEMD Resource Record conveys the digest data in the zone 21 itself. When used in combination with DNSSEC, ZONEMD allows 22 recipients to verify the zone contents for data integrity and origin 23 authenticity. This provides assurance that received zone data 24 matches published data, regardless of how the zone data has been 25 transmitted and received. When used without DNSSEC, ZONEMD functions 26 as a checksum, guarding only against unintentional changes. 28 ZONEMD does not replace DNSSEC. Whereas DNSSEC protects individual 29 RRSets (DNS data with fine granularity), ZONEMD protects a zone's 30 data as a whole, whether consumed by authoritative name servers, 31 recursive name servers, or any other applications. 33 As specified herein, ZONEMD is impractical for large, dynamic zones 34 due to the time and resources required for digest calculation. 35 However, The ZONEMD record is extensible so that new digest schemes 36 may be added in the future to support large, dynamic zones. 38 Status of This Memo 40 This Internet-Draft is submitted in full conformance with the 41 provisions of BCP 78 and BCP 79. 43 Internet-Drafts are working documents of the Internet Engineering 44 Task Force (IETF). Note that other groups may also distribute 45 working documents as Internet-Drafts. The list of current Internet- 46 Drafts is at https://datatracker.ietf.org/drafts/current/. 48 Internet-Drafts are draft documents valid for a maximum of six months 49 and may be updated, replaced, or obsoleted by other documents at any 50 time. It is inappropriate to use Internet-Drafts as reference 51 material or to cite them other than as "work in progress." 53 This Internet-Draft will expire on April 12, 2021. 55 Copyright Notice 57 Copyright (c) 2020 IETF Trust and the persons identified as the 58 document authors. All rights reserved. 60 This document is subject to BCP 78 and the IETF Trust's Legal 61 Provisions Relating to IETF Documents 62 (https://trustee.ietf.org/license-info) in effect on the date of 63 publication of this document. Please review these documents 64 carefully, as they describe your rights and restrictions with respect 65 to this document. Code Components extracted from this document must 66 include Simplified BSD License text as described in Section 4.e of 67 the Trust Legal Provisions and are provided without warranty as 68 described in the Simplified BSD License. 70 Table of Contents 72 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 3 73 1.1. Motivation . . . . . . . . . . . . . . . . . . . . . . . 4 74 1.2. Alternative Approaches . . . . . . . . . . . . . . . . . 4 75 1.3. Design Overview . . . . . . . . . . . . . . . . . . . . . 6 76 1.4. Use Cases . . . . . . . . . . . . . . . . . . . . . . . . 6 77 1.4.1. Root Zone . . . . . . . . . . . . . . . . . . . . . . 6 78 1.4.2. Providers, Secondaries, and Anycast . . . . . . . . . 7 79 1.4.3. Response Policy Zones . . . . . . . . . . . . . . . . 7 80 1.4.4. Centralized Zone Data Service . . . . . . . . . . . . 7 81 1.4.5. General Purpose Comparison Check . . . . . . . . . . 7 82 1.5. Terminology . . . . . . . . . . . . . . . . . . . . . . . 8 83 2. The ZONEMD Resource Record . . . . . . . . . . . . . . . . . 8 84 2.1. Non-apex ZONEMD Records . . . . . . . . . . . . . . . . . 8 85 2.2. ZONEMD RDATA Wire Format . . . . . . . . . . . . . . . . 8 86 2.2.1. The Serial Field . . . . . . . . . . . . . . . . . . 9 87 2.2.2. The Scheme Field . . . . . . . . . . . . . . . . . . 9 88 2.2.3. The Hash Algorithm Field . . . . . . . . . . . . . . 9 89 2.2.4. The Digest Field . . . . . . . . . . . . . . . . . . 10 90 2.3. ZONEMD Presentation Format . . . . . . . . . . . . . . . 10 91 2.4. ZONEMD Example . . . . . . . . . . . . . . . . . . . . . 10 92 3. Calculating the Digest . . . . . . . . . . . . . . . . . . . 11 93 3.1. Add ZONEMD Placeholder . . . . . . . . . . . . . . . . . 11 94 3.2. Optionally Sign the Zone . . . . . . . . . . . . . . . . 11 95 3.3. Scheme-Specific Processing . . . . . . . . . . . . . . . 12 96 3.3.1. The SIMPLE Scheme . . . . . . . . . . . . . . . . . . 12 97 3.3.1.1. SIMPLE Scheme Inclusion/Exclusion Rules . . . . . 12 98 3.3.1.2. SIMPLE Scheme Digest Calculation . . . . . . . . 12 99 3.4. Update ZONEMD RR . . . . . . . . . . . . . . . . . . . . 13 100 4. Verifying Zone Digest . . . . . . . . . . . . . . . . . . . . 13 101 5. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 15 102 5.1. ZONEMD RRtype . . . . . . . . . . . . . . . . . . . . . . 15 103 5.2. ZONEMD Scheme . . . . . . . . . . . . . . . . . . . . . . 15 104 5.3. ZONEMD Hash Algorithm . . . . . . . . . . . . . . . . . . 15 105 6. Security Considerations . . . . . . . . . . . . . . . . . . . 16 106 6.1. Using Zone Digest Without DNSSEC . . . . . . . . . . . . 16 107 6.2. Attacks Against the Zone Digest . . . . . . . . . . . . . 16 108 6.3. Use of Multiple ZONEMD Hash Algorithms . . . . . . . . . 17 109 6.4. DNSSEC Timing Considerations . . . . . . . . . . . . . . 17 110 6.5. Attacks Utilizing ZONEMD Queries . . . . . . . . . . . . 17 111 6.6. Resilience and Fragility . . . . . . . . . . . . . . . . 17 112 7. Performance Considerations . . . . . . . . . . . . . . . . . 18 113 7.1. SIMPLE SHA384 . . . . . . . . . . . . . . . . . . . . . . 18 114 8. Privacy Considerations . . . . . . . . . . . . . . . . . . . 19 115 9. Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . 19 116 10. Change Log . . . . . . . . . . . . . . . . . . . . . . . . . 19 117 11. References . . . . . . . . . . . . . . . . . . . . . . . . . 26 118 11.1. Normative References . . . . . . . . . . . . . . . . . . 26 119 11.2. Informative References . . . . . . . . . . . . . . . . . 27 120 Appendix A. Example Zones With Digests . . . . . . . . . . . . . 29 121 A.1. Simple EXAMPLE Zone . . . . . . . . . . . . . . . . . . . 29 122 A.2. Complex EXAMPLE Zone . . . . . . . . . . . . . . . . . . 30 123 A.3. EXAMPLE Zone with multiple digests . . . . . . . . . . . 31 124 A.4. The URI.ARPA Zone . . . . . . . . . . . . . . . . . . . . 31 125 A.5. The ROOT-SERVERS.NET Zone . . . . . . . . . . . . . . . . 34 126 Appendix B. Implementation Status . . . . . . . . . . . . . . . 36 127 B.1. Authors' Implementation . . . . . . . . . . . . . . . . . 36 128 B.2. Shane Kerr's Implementation . . . . . . . . . . . . . . . 36 129 B.3. NIC Chile Labs Implementation . . . . . . . . . . . . . . 37 130 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 37 132 1. Introduction 134 In the DNS, a zone is the collection of authoritative resource 135 records (RRs) sharing a common origin ([RFC8499]). Zones are often 136 stored as files in the so-called master file format [RFC1034]. Zones 137 are generally distributed among name servers using the AXFR (zone 138 transfer [RFC5936]), and IXFR (incremental zone transfer [RFC1995]) 139 protocols. They can also be distributed outside of the DNS, with any 140 file transfer protocol such as FTP, HTTP, and rsync, or even as email 141 attachments. Currently, there is no standard way to compute a hash 142 or message digest for a stand-alone zone. 144 This document specifies an RR type that provides a cryptographic 145 message digest of the data in a zone. It allows a receiver of the 146 zone to verify the zone's integrity, and when used in combination 147 with DNSSEC, its authenticity. The digest RR is a part of the zone 148 itself, allowing verification of the zone, no matter how it is 149 transmitted. The digest uses the wire format of zone data in a 150 canonical ordering. Thus, it is independent of presentation format, 151 such as whitespace, capitalization, and comments. 153 This specification is OPTIONAL to implement by both publishers and 154 consumers of zone data. 156 1.1. Motivation 158 The motivation for this protocol enhancement is the desire to verify 159 the data integrity and origin authenticity of a stand-alone zone, 160 regardless of how it is transmitted. A consumer of zone data should 161 be able to verify that it is as-published by the zone operator. 163 Note, however, that integrity and authenticity can only be assured 164 when the zone is signed. DNSSEC provides three strong security 165 guarantees relevant to this protocol: 167 1. whether or not to expect DNSSEC records in the zone, 169 2. whether or not to expect a ZONEMD record in a signed zone, and 171 3. whether or not the ZONEMD record has been altered since it was 172 signed. 174 A secondary motivation is to provide the equivalent of a checksum, 175 allowing a zone recipient to check for unintended changes and 176 operational errors, such as accidental truncation. 178 1.2. Alternative Approaches 180 One approach to preventing data tampering and corruption is to secure 181 the distribution channel. The DNS has a number of features that are 182 already used for channel security. Perhaps the most widely used is 183 DNS transaction signatures (TSIG [RFC2845]). TSIG uses shared secret 184 keys and a message digest to protect individual query and response 185 messages. It is generally used to authenticate and validate UPDATE 186 [RFC2136], AXFR [RFC5936], and IXFR [RFC1995] messages. 188 DNS Request and Transaction Signatures (SIG(0) [RFC2931]) is another 189 protocol extension that authenticates individual DNS transactions. 190 Whereas SIG records normally cover specific RR types, SIG(0) is used 191 to sign an entire DNS message. Unlike TSIG, SIG(0) uses public key 192 cryptography rather than shared secrets. 194 The Transport Layer Security protocol suite also provides channel 195 security. The DPRIVE working group is in the process of specifying 196 DNS Zone Transfer-over-TLS [I-D.ietf-dprive-xfr-over-tls]. One can 197 also easily imagine the distribution of zones over HTTPS-enabled web 198 servers, as well as DNS-over-HTTPS [RFC8484]. 200 Unfortunately, the protections provided by these channel security 201 techniques are (in practice) ephemeral and are not retained after the 202 data transfer is complete. They ensure that the client receives the 203 data from the expected server, and that the data sent by the server 204 is not modified during transmission. However, they do not guarantee 205 that the server transmits the data as originally published, and do 206 not provide any methods to verify data that is read after 207 transmission is complete. For example, a name server loading saved 208 zone data upon restart cannot guarantee that the on-disk data has not 209 been modified. Such modification could be the result of an 210 accidental corruption of the file, or perhaps an incompletely saved 211 file [disk-full-failure]. For these reasons, it is preferable to 212 protect the integrity of the data itself. 214 Why not simply rely on DNSSEC, which provides certain data security 215 guarantees? For zones that are signed, a recipient could validate 216 all of the signed RRSets. Additionally, denial-of-existence records 217 prove that RRSets have not been added or removed. However, 218 delegations (non-apex NS records) are not signed by DNSSEC, and 219 neither are any glue records. ZONEMD protects the integrity of 220 delegation, glue, and other records that are not otherwise covered by 221 DNSSEC. Furthermore, zones that employ NSEC3 with opt-out [RFC5155] 222 are susceptible to the removal or addition of names between the 223 signed nodes. Whereas DNSSEC primarily protects consumers of DNS 224 response messages, this protocol protects consumers of zones. 226 There are existing tools and protocols that provide data security, 227 such as OpenPGP [RFC4880] and S/MIME [RFC5751]. In fact, the 228 internic.net site publishes PGP signatures alongside the root zone 229 and other files available there. However, this is a detached 230 signature with no strong association to the corresponding zone file 231 other than its timestamp. Non-detached signatures are, of course, 232 possible, but these necessarily change the format of the file being 233 distributed; a zone signed with OpenPGP or S/MIME no longer looks 234 like a DNS zone and could not directly be loaded into a name server. 235 Once loaded the signature data is lost, so it cannot be further 236 propagated. 238 It seems the desire for data security in DNS zones was envisioned as 239 far back as 1997. [RFC2065] is an obsoleted specification of the 240 first generation DNSSEC Security Extensions. It describes a zone 241 transfer signature, identified as the AXFR SIG, which is similar to 242 the technique proposed by this document. That is, it proposes 243 ordering all (signed) RRSets in a zone, hashing their contents, and 244 then signing the zone hash. The AXFR SIG is described only for use 245 during zone transfers. It did not postulate the need to validate 246 zone data distributed outside of the DNS. Furthermore, its 247 successor, [RFC2535], omits the AXFR SIG, while at the same time 248 introducing an IXFR SIG. 250 1.3. Design Overview 252 This document specifies a new Resource Record type to convey a 253 message digest of the content of a zone. The digest is calculated at 254 the time of zone publication. If the zone is signed with DNSSEC, any 255 modifications of the digest can be detected. The procedures for 256 digest calculation and DNSSEC signing are similar. Both require data 257 to be processed in a well-defined order and format. It may be 258 possible to perform DNSSEC signing and digest calculation in 259 parallel. 261 The zone digest is designed to be used on zones that have infrequent 262 updates. As specified herein, the digest is re-calculated over the 263 entire zone content each time the zone is updated. This 264 specification does not provide an efficient mechanism for updating 265 the digest on incremental updates of zone data. It is, however, 266 extensible so that future schemes may be defined to support efficient 267 incremental digest updates. 269 It is expected that verification of a zone digest will be implemented 270 in name server software. That is, a name server can verify the zone 271 data it was given and refuse to serve a zone which fails 272 verification. For signed zones, the name server needs a trust anchor 273 to perform DNSSEC validation. For signed non-root zones, the name 274 server may need to send queries to validate a chain of trust. Digest 275 verification could also be performed externally. 277 1.4. Use Cases 279 1.4.1. Root Zone 281 The root zone [InterNIC] is one of the most widely distributed DNS 282 zone on the Internet, served by more than 1000 separate instances 283 [RootServers] at the time of this writing. Additionally, many 284 organizations configure their own name servers to serve the root zone 285 locally. Reasons for doing so include privacy and reduced access 286 time. [RFC8806] describes one way to do this. As the root zone 287 spreads beyond its traditional deployment boundaries, the 288 verification of the completeness of the zone contents becomes more 289 important. 291 1.4.2. Providers, Secondaries, and Anycast 293 Since its very early days, the developers of the DNS recognized the 294 importance of secondary name servers and service diversity. However, 295 modern DNS service has complex provisioning which includes multiple 296 third-party providers ([RFC8901]) and hundreds of anycast instances 297 ([RFC3258]). Instead of a simple primary-to-secondary zone 298 distribution system, today it is possible to have multiple levels, 299 multiple parties, and multiple protocols involved in the distribution 300 of zone data. This complexity introduces new places for problems to 301 arise. The zone digest protects the integrity of data that flows 302 through such systems. 304 1.4.3. Response Policy Zones 306 A Response Policy Zone (RPZ) is "a mechanism to introduce a 307 customized policy in Domain Name System servers, so that recursive 308 resolvers return possibly modified results" [RPZ]. The policy 309 information is carried inside specially constructed DNS zones. A 310 number of companies provide RPZ feeds, which are consumed by name 311 server and firewall products. While RPZ zones can be signed with 312 DNSSEC, the data is not queried directly, and would not be subject to 313 DNSSEC validation. 315 1.4.4. Centralized Zone Data Service 317 ICANN operates the Centralized Zone Data Service [CZDS], which is a 318 repository of top-level domain zone files. Users that have been 319 granted access are then able to download zone data. Adding a zone 320 digest to these would provide CZDS users with assurances that the 321 data has not been modified between origination and retrieval. Note 322 that ZONEMD could be added to zone data supplied to CZDS without 323 requiring it to be present in the zone data served by production name 324 servers, since the digest is inherently attached to the specific copy 325 of the zone. 327 1.4.5. General Purpose Comparison Check 329 Since the zone digest calculation does not depend on presentation 330 format, it could be used to compare multiple copies of a zone 331 received from different sources, or copies generated by different 332 processes. In this case, it serves as a checksum and can be useful 333 even for unsigned zones. 335 1.5. Terminology 337 The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", 338 "SHOULD", "SHOULD NOT", "RECOMMENDED", "NOT RECOMMENDED", "MAY", and 339 "OPTIONAL" in this document are to be interpreted as described in BCP 340 14 [RFC2119] [RFC8174] when, and only when, they appear in all 341 capitals, as shown here. 343 The terms Private Use, Reserved, Unassigned, and Specification 344 Required are to be interpreted as defined in [RFC8126]. 346 2. The ZONEMD Resource Record 348 This section describes the ZONEMD Resource Record, including its 349 fields, wire format, and presentation format. The Type value for the 350 ZONEMD RR is 63. The ZONEMD RR is class independent. The RDATA of 351 the resource record consists of four fields: Serial, Scheme, Hash 352 Algorithm, and Digest. 354 A zone MAY contain multiple ZONEMD RRs to support algorithm agility 355 [RFC7696]. [RFC Editor: change that to BCP 201] When multiple ZONEMD 356 RRs are present, each MUST specify a unique Scheme and Hash Algorithm 357 tuple. It is RECOMMENDED that a zone include only one ZONEMD RR, 358 unless the zone publisher is in the process of transitioning to a new 359 Scheme or Hash Algorithm. 361 2.1. Non-apex ZONEMD Records 363 This document specifies ZONEMD RRs located at the zone apex. Non- 364 apex ZONEMD RRs are not forbidden, but have no meaning in this 365 specification. Non-apex ZONEMD RRs MUST NOT be used for 366 verification. 368 During digest calculation, non-apex ZONEMD RRs are treated as 369 ordinary RRs. They are digested as-is and the RR is not replaced by 370 a placeholder RR. 372 Unless explicitly stated otherwise, "ZONEMD" always refers to apex 373 records throughout this document. 375 2.2. ZONEMD RDATA Wire Format 377 The ZONEMD RDATA wire format is encoded as follows: 379 1 1 1 1 1 1 1 1 1 1 2 2 2 2 2 2 2 2 2 2 3 3 380 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 1 381 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 382 | Serial | 383 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 384 | Scheme |Hash Algorithm | | 385 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | 386 | Digest | 387 / / 388 / / 389 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 391 2.2.1. The Serial Field 393 The Serial field is a 32-bit unsigned integer in network byte order. 394 It is the serial number from the zone's SOA record ([RFC1035] section 395 3.3.13) for which the zone digest was generated. 397 It is included here to clearly bind the ZONEMD RR to a particular 398 version of the zone's content. Without the serial number, a stand- 399 alone ZONEMD digest has no obvious association to any particular 400 instance of a zone. 402 2.2.2. The Scheme Field 404 The Scheme field is an 8-bit unsigned integer that identifies the 405 methods by which data is collated and presented as input to the 406 hashing function. 408 Herein, SIMPLE, with Hash Algorithm value 1, is the only standardized 409 Scheme defined for ZONEMD records and it MUST be implemented. The 410 Scheme registry is further described in Section 5. 412 Scheme values 240-254 are allocated for Private Use. 414 2.2.3. The Hash Algorithm Field 416 The Hash Algorithm field is an 8-bit unsigned integer that identifies 417 the cryptographic hash algorithm used to construct the digest. 419 Herein, SHA384 [RFC6234], with value 1, is the only standardized Hash 420 Algorithm defined for ZONEMD records that MUST be implemented. When 421 SHA384 is used, the size of the Digest field is 48 octets. The 422 result of the SHA384 digest algorithm MUST NOT be truncated, and the 423 entire 48 octet digest is published in the ZONEMD record. 425 SHA512 [RFC6234], with Hash Algorithm value 2, is also defined for 426 ZONEMD records, and SHOULD be implemented. When SHA512 is used, the 427 size of the Digest field is 64 octets. The result of the SHA512 428 digest algorithm MUST NOT be truncated, and the entire 64 octet 429 digest is published in the ZONEMD record. 431 Hash Algorithm values 240-254 are allocated for Private Use. 433 The Hash Algorithm registry is further described in Section 5. 435 2.2.4. The Digest Field 437 The Digest field is a variable-length sequence of octets containing 438 the output of the hash algorithm. The length of the Digest field is 439 determined by deducting the fixed size of the Serial, Scheme, and 440 Hash Algorithm fields from the RDATA size in the ZONEMD RR header. 442 The Digest field MUST NOT be shorter than 12 octets. Digests for the 443 SHA384 and SHA512 hash algorithms specified herein are never 444 truncated. Digests for future hash algorithms MAY be truncated, but 445 MUST NOT be truncated to a length that results in less than 96-bits 446 (12 octets) of equivalent strength. 448 Section 3 describes how to calculate the digest for a zone. 449 Section 4 describes how to use the digest to verify the contents of a 450 zone. 452 2.3. ZONEMD Presentation Format 454 The presentation format of the RDATA portion is as follows: 456 The Serial field is represented as an unsigned decimal integer. 458 The Scheme field is represented as an unsigned decimal integer. 460 The Hash Algorithm field is represented as an unsigned decimal 461 integer. 463 The Digest is represented as a sequence of case-insensitive 464 hexadecimal digits. Whitespace is allowed within the hexadecimal 465 text. 467 2.4. ZONEMD Example 469 The following example shows a ZONEMD RR in presentation format: 471 example.com. 86400 IN ZONEMD 2018031500 1 1 ( 472 FEBE3D4CE2EC2FFA4BA99D46CD69D6D29711E55217057BEE 473 7EB1A7B641A47BA7FED2DD5B97AE499FAFA4F22C6BD647DE ) 475 3. Calculating the Digest 477 The algorithm described in this section is designed for the common 478 case of offline DNSSEC signing. Slight deviations may be permitted 479 or necessary in other situations, such as with unsigned zones or 480 online DNSSEC signing. Implementations that deviate from the 481 described algorithm are advised to ensure that identical ZONEMD RRs, 482 signatures, and dential-of-existence records are produced. 484 3.1. Add ZONEMD Placeholder 486 In preparation for calculating the zone digest(s), any existing 487 ZONEMD records (and covering RRSIGs) at the zone apex are first 488 deleted. 490 Prior to calculation of the digest, and prior to signing with DNSSEC, 491 one or more placeholder ZONEMD records are added to the zone apex. 492 This ensures that denial-of-existence (NSEC, NSEC3) records are 493 created correctly if the zone is signed with DNSSEC. If placeholders 494 were not added prior to signing, the later addition of ZONEMD records 495 would also require updating the Type Bit Maps field of any apex NSEC/ 496 NSEC3 RRs, which then invalidates the calculated digest value. 498 When multiple ZONEMD RRs are published in the zone, e.g., during an 499 algorithm rollover, each MUST specify a unique Scheme and Hash 500 Algorithm tuple. 502 It is RECOMMENDED that the TTL of the ZONEMD record match the TTL of 503 the SOA. However, the TTL of the ZONEMD record may be safely ignored 504 during verification in all cases. 506 In the placeholder record, the Serial field is set to the current SOA 507 Serial. The Scheme field is set to the value for the chosen 508 collation scheme. The Hash Algorithm field is set to the value for 509 the chosen hash algorithm. Since apex ZONEMD records are excluded 510 from digest calculation, the value of the Digest field does not 511 matter at this point in the process. 513 3.2. Optionally Sign the Zone 515 Following addition of placeholder records, the zone may be signed 516 with DNSSEC. When the digest calculation is complete, and the ZONEMD 517 record is updated, the signature(s) for the ZONEMD RRSet MUST be 518 recalculated and updated as well. Therefore, the signer is not 519 required to calculate a signature over the placeholder record at this 520 step in the process, but it is harmless to do so. 522 3.3. Scheme-Specific Processing 524 Herein, only the SIMPLE collation scheme is defined. Additional 525 schemes may be defined in future updates to this document. 527 3.3.1. 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 Calculation of a zone digest requires RRs to be processed in a 536 consistent format and ordering. This specification uses DNSSEC's 537 canonical on-the-wire RR format (without name compression) and 538 ordering as specified in Sections 6.1, 6.2, and 6.3 of [RFC4034] with 539 the additional provision that RRSets having the same owner name MUST 540 be numerically ordered, in ascending order, by their numeric RR TYPE. 542 3.3.1.1. SIMPLE Scheme Inclusion/Exclusion Rules 544 When iterating over records in the zone, the following inclusion/ 545 exclusion rules apply: 547 o All records in the zone, including glue records, MUST be included, 548 unless excluded by a subsequent rule. 550 o Occluded data ([RFC5936] Section 3.5) MUST be included. 552 o If there are duplicate RRs with equal owner, class, type, and 553 RDATA, only one instance is included ([RFC4034] Section 6.3), and 554 the duplicates MUST be omitted. 556 o The placeholder apex ZONEMD RR(s) MUST NOT be included. 558 o If the zone is signed, DNSSEC RRs MUST be included, except: 560 o The RRSIG covering the apex ZONEMD RRSet MUST NOT be included 561 because the RRSIG will be updated after all digests have been 562 calculated. 564 3.3.1.2. SIMPLE Scheme Digest Calculation 566 A zone digest using the SIMPLE scheme is calculated by concatenating 567 all RRs in the zone, in the format and order described in 568 Section 3.3.1 subject to the inclusion/exclusion rules described in 569 Section 3.3.1.1, and then applying the chosen hash algorithm: 571 digest = hash( RR(1) | RR(2) | RR(3) | ... ) 573 where "|" denotes concatenation. 575 3.4. Update ZONEMD RR 577 The calculated zone digest is inserted into the placeholder ZONEMD 578 RR. Repeat for each digest if multiple digests are to be published. 580 If the zone is signed with DNSSEC, the RRSIG record(s) covering the 581 ZONEMD RRSet MUST then be added or updated. Because the ZONEMD 582 placeholder was added prior to signing, the zone will already have 583 the appropriate denial-of-existence (NSEC, NSEC3) records. 585 Some DNSSEC implementations (especially "online signing") might 586 update the SOA serial number whenever a new signature is made. To 587 preserve the calculated digest, generation of a ZONEMD signature MUST 588 NOT also result in a change to the SOA serial number. The ZONEMD RR 589 and the matching SOA MUST be published at the same time. 591 4. Verifying Zone Digest 593 The recipient of a zone that has a ZONEMD RR verifies the zone by 594 calculating the digest as follows. If multiple ZONEMD RRs are 595 present in the zone, e.g., during an algorithm rollover, a match 596 using any one of the recipient's supported Schemes and Hash 597 Algorithms is sufficient to verify the zone. The verifier MAY ignore 598 a ZONEMD RR if its Scheme and Hash Algorithm violates local policy. 600 1. The verifier MUST first determine whether or not to expect DNSSEC 601 records in the zone. This is done by examining locally 602 configured trust anchors, and, if necessary, querying for (and 603 validating) DS RRs in the anchors, or querying for (and 604 validating) DS RRs in the parent zone. For zones that are 605 provably insecure, or if DNSSEC validation is not performed, 606 digest verification continues at step 4 below. 608 2. For zones that are provably secure, the existence of the apex 609 ZONEMD record MUST be verified. If the ZONEMD record provably 610 does not exist, digest verification cannot occur. If the ZONEMD 611 record does provably exist, but is not found in the zone, digest 612 verification MUST NOT be considered successful. 614 3. For zones that are provably secure, the SOA and ZONEMD RRSets 615 MUST have valid signatures, chaining up to a trust anchor. If 616 DNSSEC validation of the SOA or ZONEMD records fails, digest 617 verification MUST NOT be considered successful. 619 4. When multiple ZONEMD RRs are present, each MUST specify a unique 620 Scheme and Hash Algorithm tuple. If the ZONEMD RRSet contains 621 more than one RR with the same Scheme and Hash Algorithm, digest 622 verification for those ZONEMD RRs MUST NOT be considered 623 successful. 625 5. Loop over all apex ZONEMD RRs and perform the following steps: 627 A. The SOA Serial field MUST exactly match the ZONEMD Serial 628 field. If the fields do not match, digest verification MUST 629 NOT be considered successful with this ZONEMD RR. 631 B. The Scheme field MUST be checked. If the verifier does not 632 support the given scheme, verification MUST NOT be considered 633 successful with this ZONEMD RR and it SHOULD report that the 634 RR's digest could not be verified due to an unsupported 635 scheme. 637 C. The Hash Algorithm field MUST be checked. If the verifier 638 does not support the given hash algorithm, verification MUST 639 NOT be considered successful with this ZONEMD RR and it 640 SHOULD report that the RR's digest could not be verified due 641 to an unsupported algorithm. 643 D. The Digest field size MUST be checked. If the size of the 644 given Digest field is smaller than 12 octets, or if the size 645 is not equal to the size expected for the corresponding Hash 646 Algorithm, verification MUST NOT be considered successful 647 with this ZONEMD RR and the verifier SHOULD report that the 648 RR's digest could not be verified due to an incorrect digest 649 length. 651 E. The zone digest is computed over the zone data as described 652 in Section 3.3, using the Scheme and Hash Algorithm for the 653 current ZONEMD RR. 655 F. The computed digest is compared to the received digest. If 656 the two digest values match, verification is considered 657 successful. Otherwise, verification MUST NOT be considered 658 successful for this ZONEMD RR. 660 [ Maybe remove all the "SHOULD report" above and just say this:] 662 Each time zone verification is performed, the verifier SHOULD report 663 the status as either successful or unsuccessful. When unsuccessful, 664 the verifier SHOULD report the reason(s) that verification did not 665 succeed. 667 5. IANA Considerations 669 5.1. ZONEMD RRtype 671 This document defines a new DNS RR type, ZONEMD, whose value 63 has 672 been allocated by IANA from the "Resource Record (RR) TYPEs" 673 subregistry of the "Domain Name System (DNS) Parameters" registry: 675 Type: ZONEMD 677 Value: 63 679 Meaning: Message Digest Over Zone Data 681 Reference: [this document] 683 5.2. ZONEMD Scheme 685 IANA is requested to create a new registry on the "Domain Name System 686 (DNS) Parameters" web page as follows: 688 Registry Name: ZONEMD Schemes 690 Registration Procedure: Specification Required 692 Reference: [this document] 694 +---------+-------------------------+----------+-----------------+ 695 | Value | Description | Mnemonic | Reference | 696 +---------+-------------------------+----------+-----------------+ 697 | 0 | Reserved | | | 698 | 1 | Simple ZONEMD collation | SIMPLE | [this document] | 699 | 2-239 | Unassigned | | | 700 | 240-254 | Private Use | N/A | [this document] | 701 | 255 | Reserved | | | 702 +---------+-------------------------+----------+-----------------+ 704 Table 1: ZONEMD Scheme Registry 706 5.3. ZONEMD Hash Algorithm 708 IANA is requested to create a new registry on the "Domain Name System 709 (DNS) Parameters" web page as follows: 711 Registry Name: ZONEMD Hash Algorithms 713 Registration Procedure: Specification Required 714 Reference: [this document] 716 +---------+-------------+----------+-----------------+ 717 | Value | Description | Mnemonic | Reference | 718 +---------+-------------+----------+-----------------+ 719 | 0 | Reserved | | | 720 | 1 | SHA-384 | SHA384 | [this document] | 721 | 2 | SHA-512 | SHA512 | [this document] | 722 | 3-239 | Unassigned | | | 723 | 240-254 | Private Use | N/A | [his document] | 724 | 255 | Reserved | | | 725 +---------+-------------+----------+-----------------+ 727 Table 2: ZONEMD Hash Algorithm Registry 729 6. Security Considerations 731 6.1. Using Zone Digest Without DNSSEC 733 Users of ZONEMD with unsigned zones are advised that it provides no 734 real protection against attacks. While zone digests can be used in 735 the absence of DNSSEC, this only provides protection against 736 accidental zone corruption, such as transmission errors and 737 truncation. When used in this manner, it effectively serves only as 738 a checksum. For zones not signed with DNSSEC, an attacker can make 739 any zone modifications appear to be valid by recomputing Digest field 740 of a ZONEMD RR. 742 6.2. Attacks Against the Zone Digest 744 An attacker, whose goal is to modify zone content before it is used 745 by the victim, may consider a number of different approaches. 747 The attacker might perform a downgrade attack to an unsigned zone. 748 This is why Section 4 talks about determining whether or not to 749 expect DNSSEC signatures for the zone in step 1. 751 The attacker might perform a downgrade attack by removing one or more 752 ZONEMD records. Such a removal is detectable only with DNSSEC 753 validation and is why Section 4 talks about checking denial-of- 754 existence proofs in step 2 and signature validation in step 3. 756 The attacker might alter the Scheme, Hash Algorithm, or Digest fields 757 of the ZONEMD record. Such modifications are detectable only with 758 DNSSEC validation. 760 As stated in [RFC7696], cryptographic algorithms age and become 761 weaker as cryptanalysis techniques and computing resources improve 762 with time. Implementors and publishers of zone digests should 763 anticipate the need for algorithm agility on long timescales. 765 6.3. Use of Multiple ZONEMD Hash Algorithms 767 When a zone publishes multiple ZONEMD RRs, the overall security is 768 only as good as the weakest hash algorithm in use. For this reason, 769 Section 2 recommends only publishing multiple ZONEMD RRs when 770 transitioning to a new scheme or hash algorithm. Once the transition 771 is complete, the old scheme or hash algorithm should be removed from 772 the ZONEMD RRSet. 774 6.4. DNSSEC Timing Considerations 776 As with all DNSSEC signatures, the ability to perform signature 777 validation of a ZONEMD record is limited in time. If the DS 778 record(s) or trust anchors for the zone to be verified are no longer 779 available, the recipient cannot validate the ZONEMD RRSet. This 780 could happen even if the ZONEMD signature is still current (not 781 expired), since the zone's DS record(s) may have been withdrawn 782 following a Key Signing Key (KSK) rollover. 784 For zones where it may be important to validate a ZONEMD RRSet 785 through its entire signature validity period, the zone operator 786 should ensure that KSK rollover timing takes this into consideration. 788 6.5. Attacks Utilizing ZONEMD Queries 790 Nothing in this specification prevents clients from making, and 791 servers from responding to, ZONEMD queries. Servers SHOULD NOT 792 calculate zone digests dynamically (for each query) as this can be 793 used as a CPU resource exhaustion attack. 795 ZONEMD responses could be used in a distributed denial-of-service 796 amplification attack. The ZONEMD RR is moderately sized, much like 797 the DS RR. A single ZONEMD RR contributes approximately 65 to 95 798 octets to a DNS response, for digest types defined herein. Other RR 799 types, such as DNSKEY, can result in larger amplification effects. 801 6.6. Resilience and Fragility 803 ZONEMD is used to detect incomplete or corrupted zone data prior to 804 its use, thereby increasing resilience by not using corrupt data, but 805 also introduces some denial-of-service fragility by making good data 806 in a zone unavailable if some other data is missing or corrupt. 807 Publishers and consumers of zones containing ZONEMD records should be 808 aware of these tradeoffs. While the intention is to secure the zone 809 data, misconfigurations or implementation bugs are generally 810 indistinguishable from intentional tampering, and could lead to 811 service failures when verification is performed automatically. 813 Zone publishers may want to deploy ZONEMD gradually, perhaps by 814 utilizing one of the private use hash algorithm code points listed in 815 Section 5.3. Similarly, recipients may want to initially configure 816 verification failures only as a warning, and later as an error after 817 gaining experience and confidence with the feature. 819 7. Performance Considerations 821 This section is provided to make zone publishers aware of the 822 performance requirements and implications of including ZONEMD RRs in 823 a zone. 825 7.1. SIMPLE SHA384 827 As mentioned previously, the SIMPLE scheme may be impractical for use 828 in zones that are either large or highly dynamic. Zone publishers 829 should carefully consider the use of ZONEMD in such zones, since it 830 might cause consumers of zone data (e.g., secondary name servers) to 831 expend resources on digest calculation. For such use cases, it is 832 recommended that ZONEMD only be used when digest calculation time is 833 significantly less than propagation times and update intervals. 835 The authors' implementation (Appendix B.1) includes an option to 836 record and report CPU usage of its operation. The software was used 837 to generate digests for more than 800 TLD zones available from 838 [CZDS]. The table below summarizes the results for the SIMPLE scheme 839 and SHA384 hash algorithm grouped by zone size. The Rate column is 840 the mean amount of time per RR to calculate the digest, running on 841 commodity hardware in early 2020. 843 +---------------------+----------------+ 844 | Zone Size (RRs) | Rate (msec/RR) | 845 +---------------------+----------------+ 846 | 10 - 99 | 0.00683 | 847 | 100 - 999 | 0.00551 | 848 | 1000 - 9999 | 0.00505 | 849 | 10000 - 99999 | 0.00602 | 850 | 100000 - 999999 | 0.00845 | 851 | 1000000 - 9999999 | 0.0108 | 852 | 10000000 - 99999999 | 0.0148 | 853 +---------------------+----------------+ 855 For example, based on the above table, it takes approximately 0.13 856 seconds to calculate a SIMPLE SHA384 digest for a zone with 22,000 857 RRs, and about 2.5 seconds for a zone with 300,000 RRs. 859 These benchmarks attempt to emulate a worst-case scenario and take 860 into account the time required to canonicalize the zone for 861 processing. Each of the 800+ zones were measured three times, and 862 then averaged, with a different random sorting of the input data 863 prior to each measurement. 865 8. Privacy Considerations 867 This specification has no impact on user privacy. 869 9. Acknowledgments 871 The authors wish to thank David Blacka, Scott Hollenbeck, and Rick 872 Wilhelm for providing feedback on early drafts of this document. 873 Additionally, they thank Joe Abley, Mark Andrews, Ralph Dolmans, 874 Donald Eastlake, Richard Gibson, Olafur Gudmundsson, Bob Harold, Paul 875 Hoffman, Evan Hunt, Shumon Huque, Tatuya Jinmei, Mike St. Johns, Burt 876 Kaliski, Shane Kerr, Matt Larson, Barry Leiba, John Levine, Ed Lewis, 877 Matt Pounsett, Mukund Sivaraman, Petr Spacek, Ondrej Sury, Willem 878 Toorop, Florian Weimer, Tim Wicinski, Wouter Wijngaards, Paul 879 Wouters, and other members of the DNSOP working group for their 880 input. 882 10. Change Log 884 RFC Editor: Please remove this section before publication. 886 This section lists substantial changes to the document as it is being 887 worked on. 889 From -00 to -01: 891 o Removed requirement to sort by RR CLASS. 893 o Added Kumari and Hardaker as coauthors. 895 o Added Change Log section. 897 o Minor clarifications and grammatical edits. 899 From -01 to -02: 901 o Emphasize desire for data security over channel security. 903 o Expanded motivation into its own subsection. 905 o Removed discussion topic whether or not to include serial in 906 ZONEMD. 908 o Clarified that a zone's NS records always sort before the SOA 909 record. 911 o Clarified that all records in the zone must are digested, except 912 as specified in the exclusion rules. 914 o Added for discussion out-of-zone and occluded records. 916 o Clarified that update of ZONEMD signature must not cause a serial 917 number change. 919 o Added persons to acknowledgments. 921 From -02 to -03: 923 o Added recommendation to set ZONEMD TTL to SOA TTL. 925 o Clarified that digest input uses uncompressed names. 927 o Updated Implementations section. 929 o Changed intended status from Standards Track to Experimental and 930 added Scope of Experiment section. 932 o Updated Motivation, Introduction, and Design Overview sections in 933 response to working group discussion. 935 o Gave ZONEMD digest types their own status, separate from DS digest 936 types. Request IANA to create a registry. 938 o Added Reserved field for future work supporting dynamic updates. 940 o Be more rigorous about having just ONE ZONEMD record in the zone. 942 o Expanded use cases. 944 From -03 to -04: 946 o Added an appendix with example zones and digests. 948 o Clarified that only apex ZONEMD RRs shall be processed. 950 From -04 to -05: 952 o Made SHA384 the only supported ZONEMD digest type. 954 o Disassociated ZONEMD digest types from DS digest types. 956 o Updates to Introduction based on list feedback. 958 o Changed "zone file" to "zone" everywhere. 960 o Restored text about why ZONEMD has a Serial field. 962 o Clarified ordering of RRSets having same owner to be numerically 963 ascending. 965 o Clarified that all duplicate RRs (not just SOA) must be suppressed 966 in digest calculation. 968 o Clarified that the Reserved field must be set to zero and checked 969 for zero in verification. 971 o Clarified that occluded data must be included. 973 o Clarified procedure for verification, using temporary location for 974 received digest. 976 o Explained why Reserved field is 8-bits. 978 o IANA Considerations section now more specific. 980 o Added complex zone to examples. 982 o 984 From -05 to -06: 986 o RR type code 63 was assigned to ZONEMD by IANA. 988 From -06 to -07: 990 o Fixed mistakes in ZONEMD examples. 992 o Added private use Digest Type values 240-254. 994 o Clarified that Digest field must not be empty. 996 From -07 to draft-ietf-dnsop-dns-zone-digest-00: 998 o Adopted by dnsop. 1000 o Clarified further that non-apex ZONEMD RRs have no meaning. 1002 o Changed "provably [un]signed" to "provably [in]secure". 1004 o Allow multiple ZONEMD RRs to support algorithm agility/rollovers. 1006 o Describe verification when there are multiple ZONEMD RRs. 1008 From -00 to -01: 1010 o Simplified requirements around verifying multiple digests. Any 1011 one match is sufficient. 1013 o Updated implementation notes. 1015 o Both implementations produce expected results on examples given in 1016 this document. 1018 From -01 to -02: 1020 o Changed the name of the Reserved field to Parameter. 1022 o Changed the name of Digest Type 1 from SHA384 to SHA384-STABLE. 1024 o The meaning of the Parameter field now depends on Digest Type. 1026 o No longer require Parameter field to be zero in verification. 1028 o Updated a rule from earlier versions that said multiple ZONEMD RRs 1029 were not allowed. 1031 From -02 to -03: 1033 o Changed the name of Digest Type 1 from SHA384-STABLE to 1034 SHA384-SIMPLE. 1036 o Changed document status from Experimental to Standards Track. 1038 o Removed Scope of Experimentation section. 1040 From -03 to -04: 1042 o Addressing WGLC feedback. 1044 o Changed from "Digest Type + Paramter" to "Scheme + Hash 1045 Algorithm". This should make it more obvious how ZONEMD can be 1046 expanded in the future with new schemes and hash algorithms, while 1047 sacrificing some of the flexibility that the Parameter was 1048 intended to provide. 1050 o Note: old RDATA fields: Serial, Digest Type, Parameter, Digest. 1052 o Note: new RDATA fields: Serial, Scheme, Hash Algorithm, Digest. 1054 o Add new IANA requirement for a Scheme registry. 1056 o Rearranged some sections and separated scheme-specific aspects 1057 from general aspects of digest calculation. 1059 o When discussing multiple ZONEMD RRs, allow for Scheme, as well as 1060 Hash Algorithm, transition. 1062 o Added Performance Considerations section with some benchmarks. 1064 o Further clarifications about non-apex ZONEMD RRs. 1066 o Clarified inclusion rule for duplicate RRs. 1068 o Removed or lowercased some inappropriately used RFC 2119 key 1069 words. 1071 o Clarified that all ZONEMD RRs, even for unsupported hash 1072 algorithms, must be zeroized during digest calculation. 1074 o Added Resilience and Fragility to security considerations. 1076 o Updated examples since changes in this version result in different 1077 hash values. 1079 From -04 to -05: 1081 o Clarifications about non-apex and multiple ZONEMD RRs. 1083 o Clarifications about benchmark results. 1085 o Don't compute ZONEMD on-the-fly. 1087 o Specification Required for updates to ZONEMD protocol registries. 1089 o Other rewording based on WGLC feedback. 1091 o Updated RFC numbers for some references. 1093 o Use documentation IP addresses instead of loopback. 1095 o Updated examples in the appendix. 1097 From -05 to -06: 1099 o Per WG suggestion, no longer include any apex ZONEMD record in 1100 digest calculation. 1102 o Updated examples in the appendix. 1104 o Clarified verification procedure by describing a loop over all 1105 ZONEMD RRs. 1107 From -06 to -07: 1109 o Added NIC Chile Labs implementation. 1111 From -07 to -08: 1113 o Update an author's affiliation. 1115 o Clarified why placeholder RRs are still important (for NSEC/ 1116 NSEC3). 1118 o Moved subsection ("Order of RRSets Having the Same Owner Name") 1119 with single sentence paragraph up into parent section. 1121 From -08 to -09: 1123 o Moved format, ordering, inclusion/exclusion into a sub section 1124 specific to the SIMPLE scheme. 1126 o Further clarified rules about multiple ZONEMD RRs (AD comments). 1128 o Reworded rules about processing of duplicate zone RRs (AD 1129 comments). 1131 o Removed sentence about optional zeroing of digest prior to 1132 calculation (AD comments). 1134 o Other minor changes (AD comments). 1136 From -09 to -10: 1138 o Add clarification and reference to on-disk modification / 1139 corruption of zone files. 1141 o Added concerns that timing of KSK rollovers could affect 1142 validation of ZONEMD record. 1144 o Addressed SECDIR review and accepted most proposed edits. 1146 o From SECDIR review, require minimum digest length of 12 octets. 1148 o From SECDIR review, add SHA512 has hash algorithm 2. 1150 o From SECDIR review, say that ZONEMD RRs MAY be ignored by local 1151 policy. 1153 o Moved Implementation Status to an appendix with the intention to 1154 retain it in RFC. 1156 o In registry tables, changed Status column to Implementation 1157 Requirement. 1159 From -10 to -11: 1161 o Fixed people's names in the acknowledgments section (blush) 1163 o Say "has not been modified between origination and retrieval." 1165 o Say that ZONEMD TTL doesn't matter during verification. 1167 o Further clarification that the SHA-384 and SHA-512 hashes are not 1168 truncated. Future algs might be truncated, but never below 96 1169 bits. 1171 From -11 to -12: 1173 o SECDIR review: make "recommended" all caps. 1175 o SECDIR review: tweak explanation of why ZONEMD RR has copy of SOA 1176 serial. 1178 o SECDIR review: be even more clear about apex ZONEMD RRs vs non- 1179 apex. 1181 o SECDIR review: Forgot to delete sentence about IANA policy for 1182 adding new hash algorithms. 1184 o SECDIR review: Spell out Key Signing Key first time. 1186 o SECDIR review: say "private use hash algorithm code points." 1188 o SECDIR review: Update estimates of ZONEMD RR size. 1190 From -12 to -13: 1192 o Added reference to draft-ietf-dprive-xfr-over-tls. 1194 o Dropped Implementation Requirement from registry tables. 1196 o Added Use of Multiple ZONEMD Hash Algorithms to Security 1197 Considerations. 1199 o Added Using Zone Digest Without DNSSEC to Security Considerations. 1201 o Added notes about the need for algorithm agility due to crypto 1202 algorithm aging. 1204 o Further clarified that only with DNSSEC can ZONEMD guarantee 1205 integrity and authenticity. 1207 o For unsigned zones, ZONEMD serves only as a checksum. 1209 o Calculation algorithm is designed for common case of offline 1210 signing. Deviations may be allowed as long as the end result is 1211 the same. 1213 o Numerous small edits and clarifications from IESG reviewer 1214 comments. 1216 11. References 1218 11.1. Normative References 1220 [RFC1034] Mockapetris, P., "Domain names - concepts and facilities", 1221 STD 13, RFC 1034, DOI 10.17487/RFC1034, November 1987, 1222 . 1224 [RFC1035] Mockapetris, P., "Domain names - implementation and 1225 specification", STD 13, RFC 1035, DOI 10.17487/RFC1035, 1226 November 1987, . 1228 [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate 1229 Requirement Levels", BCP 14, RFC 2119, 1230 DOI 10.17487/RFC2119, March 1997, 1231 . 1233 [RFC4034] Arends, R., Austein, R., Larson, M., Massey, D., and S. 1234 Rose, "Resource Records for the DNS Security Extensions", 1235 RFC 4034, DOI 10.17487/RFC4034, March 2005, 1236 . 1238 [RFC6234] Eastlake 3rd, D. and T. Hansen, "US Secure Hash Algorithms 1239 (SHA and SHA-based HMAC and HKDF)", RFC 6234, 1240 DOI 10.17487/RFC6234, May 2011, 1241 . 1243 [RFC8174] Leiba, B., "Ambiguity of Uppercase vs Lowercase in RFC 1244 2119 Key Words", BCP 14, RFC 8174, DOI 10.17487/RFC8174, 1245 May 2017, . 1247 11.2. Informative References 1249 [CZDS] Internet Corporation for Assigned Names and Numbers, 1250 "Centralized Zone Data Service", October 2018, 1251 . 1253 [disk-full-failure] 1254 DENIC, "Background of the Partial Failure of the Name 1255 Service for .de Domains", May 2010, 1256 . 1259 [DnsTools] 1260 NIC Chile Labs, "DNS tools for zone signature (file, 1261 pkcs11-hsm) and validation, and zone digest (ZONEMD)", 1262 April 2020, . 1264 [I-D.ietf-dprive-xfr-over-tls] 1265 Toorop, W., Dickinson, S., Sahib, S., Aras, P., and A. 1266 Mankin, "DNS Zone Transfer-over-TLS", draft-ietf-dprive- 1267 xfr-over-tls-02 (work in progress), July 2020. 1269 [InterNIC] 1270 ICANN, "InterNIC FTP site", May 2018, 1271 . 1273 [ldns-zone-digest] 1274 Verisign, "Implementation of Message Digests for DNS Zones 1275 using the ldns library", July 2018, 1276 . 1278 [RFC1995] Ohta, M., "Incremental Zone Transfer in DNS", RFC 1995, 1279 DOI 10.17487/RFC1995, August 1996, 1280 . 1282 [RFC2065] Eastlake 3rd, D. and C. Kaufman, "Domain Name System 1283 Security Extensions", RFC 2065, DOI 10.17487/RFC2065, 1284 January 1997, . 1286 [RFC2136] Vixie, P., Ed., Thomson, S., Rekhter, Y., and J. Bound, 1287 "Dynamic Updates in the Domain Name System (DNS UPDATE)", 1288 RFC 2136, DOI 10.17487/RFC2136, April 1997, 1289 . 1291 [RFC2535] Eastlake 3rd, D., "Domain Name System Security 1292 Extensions", RFC 2535, DOI 10.17487/RFC2535, March 1999, 1293 . 1295 [RFC2845] Vixie, P., Gudmundsson, O., Eastlake 3rd, D., and B. 1296 Wellington, "Secret Key Transaction Authentication for DNS 1297 (TSIG)", RFC 2845, DOI 10.17487/RFC2845, May 2000, 1298 . 1300 [RFC2931] Eastlake 3rd, D., "DNS Request and Transaction Signatures 1301 ( SIG(0)s )", RFC 2931, DOI 10.17487/RFC2931, September 1302 2000, . 1304 [RFC3258] Hardie, T., "Distributing Authoritative Name Servers via 1305 Shared Unicast Addresses", RFC 3258, DOI 10.17487/RFC3258, 1306 April 2002, . 1308 [RFC4880] Callas, J., Donnerhacke, L., Finney, H., Shaw, D., and R. 1309 Thayer, "OpenPGP Message Format", RFC 4880, 1310 DOI 10.17487/RFC4880, November 2007, 1311 . 1313 [RFC5155] Laurie, B., Sisson, G., Arends, R., and D. Blacka, "DNS 1314 Security (DNSSEC) Hashed Authenticated Denial of 1315 Existence", RFC 5155, DOI 10.17487/RFC5155, March 2008, 1316 . 1318 [RFC5751] Ramsdell, B. and S. Turner, "Secure/Multipurpose Internet 1319 Mail Extensions (S/MIME) Version 3.2 Message 1320 Specification", RFC 5751, DOI 10.17487/RFC5751, January 1321 2010, . 1323 [RFC5936] Lewis, E. and A. Hoenes, Ed., "DNS Zone Transfer Protocol 1324 (AXFR)", RFC 5936, DOI 10.17487/RFC5936, June 2010, 1325 . 1327 [RFC7696] Housley, R., "Guidelines for Cryptographic Algorithm 1328 Agility and Selecting Mandatory-to-Implement Algorithms", 1329 BCP 201, RFC 7696, DOI 10.17487/RFC7696, November 2015, 1330 . 1332 [RFC8126] Cotton, M., Leiba, B., and T. Narten, "Guidelines for 1333 Writing an IANA Considerations Section in RFCs", BCP 26, 1334 RFC 8126, DOI 10.17487/RFC8126, June 2017, 1335 . 1337 [RFC8484] Hoffman, P. and P. McManus, "DNS Queries over HTTPS 1338 (DoH)", RFC 8484, DOI 10.17487/RFC8484, October 2018, 1339 . 1341 [RFC8499] Hoffman, P., Sullivan, A., and K. Fujiwara, "DNS 1342 Terminology", BCP 219, RFC 8499, DOI 10.17487/RFC8499, 1343 January 2019, . 1345 [RFC8806] Kumari, W. and P. Hoffman, "Running a Root Server Local to 1346 a Resolver", RFC 8806, DOI 10.17487/RFC8806, June 2020, 1347 . 1349 [RFC8901] Huque, S., Aras, P., Dickinson, J., Vcelak, J., and D. 1350 Blacka, "Multi-Signer DNSSEC Models", RFC 8901, 1351 DOI 10.17487/RFC8901, September 2020, 1352 . 1354 [RootServers] 1355 Root Server Operators, "Root Server Technical Operations", 1356 July 2018, . 1358 [RPZ] Wikipedia, "Response policy zone", May 2020, 1359 . 1362 [ZoneDigestHackathon] 1363 Kerr, S., "Prototype implementation of ZONEMD for the IETF 1364 102 hackathon in Python", July 2018, 1365 . 1367 Appendix A. Example Zones With Digests 1369 This appendix contains example zones with accurate ZONEMD records. 1370 These can be used to verify an implementation of the zone digest 1371 protocol. 1373 A.1. Simple EXAMPLE Zone 1375 Here, the EXAMPLE zone contains an SOA record, NS and glue records, 1376 and a ZONEMD record. 1378 example. 86400 IN SOA ns1 admin 2018031900 ( 1379 1800 900 604800 86400 ) 1380 86400 IN NS ns1 1381 86400 IN NS ns2 1382 86400 IN ZONEMD 2018031900 1 1 ( 1383 c68090d90a7aed71 1384 6bc459f9340e3d7c 1385 1370d4d24b7e2fc3 1386 a1ddc0b9a87153b9 1387 a9713b3c9ae5cc27 1388 777f98b8e730044c ) 1389 ns1 3600 IN A 203.0.113.63 1390 ns2 3600 IN AAAA 2001:db8::63 1392 A.2. Complex EXAMPLE Zone 1394 Here, the EXAMPLE zone contains duplicate RRs, and an occluded RR, 1395 and one out-of-zone RR. 1397 example. 86400 IN SOA ns1 admin 2018031900 ( 1398 1800 900 604800 86400 ) 1399 86400 IN NS ns1 1400 86400 IN NS ns2 1401 86400 IN ZONEMD 2018031900 1 1 ( 1402 31cefb03814f5062 1403 ad12fa951ba0ef5f 1404 8da6ae354a415767 1405 246f7dc932ceb1e7 1406 42a2108f529db6a3 1407 3a11c01493de358d ) 1408 ns1 3600 IN A 203.0.113.63 1409 ns2 3600 IN AAAA 2001:db8::63 1410 occluded.sub 7200 IN TXT "I'm occluded but must be digested" 1411 sub 7200 IN NS ns1 1412 duplicate 300 IN TXT "I must be digested just once" 1413 duplicate 300 IN TXT "I must be digested just once" 1414 foo.test. 555 IN TXT "out-of-zone data must be excluded" 1415 non-apex 900 IN ZONEMD 2018031900 1 1 ( 1416 616c6c6f77656420 1417 6275742069676e6f 1418 7265642e20616c6c 1419 6f77656420627574 1420 2069676e6f726564 1421 2e20616c6c6f7765 ) 1423 A.3. EXAMPLE Zone with multiple digests 1425 Here, the EXAMPLE zone contains multiple ZONEMD records. It has both 1426 SHA384 and SHA512 digests using the SIMPLE scheme. It also includes 1427 ZONEMD records with Scheme and Hash Algorithm values in the private 1428 range (240-254). These additional private-range digests are not 1429 verifiable. 1431 example. 86400 IN SOA ns1 admin 2018031900 ( 1432 1800 900 604800 86400 ) 1433 example. 86400 IN NS ns1.example. 1434 example. 86400 IN NS ns2.example. 1435 example. 86400 IN ZONEMD 2018031900 1 1 ( 1436 62e6cf51b02e54b9 1437 b5f967d547ce4313 1438 6792901f9f88e637 1439 493daaf401c92c27 1440 9dd10f0edb1c56f8 1441 080211f8480ee306 ) 1442 example. 86400 IN ZONEMD 2018031900 1 2 ( 1443 08cfa1115c7b948c 1444 4163a901270395ea 1445 226a930cd2cbcf2f 1446 a9a5e6eb85f37c8a 1447 4e114d884e66f176 1448 eab121cb02db7d65 1449 2e0cc4827e7a3204 1450 f166b47e5613fd27 ) 1451 example. 86400 IN ZONEMD 2018031900 1 240 ( 1452 e2d523f654b9422a 1453 96c5a8f44607bbee ) 1454 example. 86400 IN ZONEMD 2018031900 241 1 ( 1455 e1846540e33a9e41 1456 89792d18d5d131f6 1457 05fc283e ) 1458 ns1.example. 3600 IN A 203.0.113.63 1459 ns2.example. 86400 IN TXT "This example has multiple digests" 1460 ns2.example. 3600 IN AAAA 2001:db8::63 1462 A.4. The URI.ARPA Zone 1464 The URI.ARPA zone retrieved 2018-10-21. Note this sample zone has 1465 (expired) signatures, but no signature for the ZONEMD RR. 1467 ; <<>> DiG 9.9.4 <<>> @lax.xfr.dns.icann.org uri.arpa axfr 1468 ; (2 servers found) 1469 ;; global options: +cmd 1470 uri.arpa. 3600 IN SOA sns.dns.icann.org. ( 1471 noc.dns.icann.org. 2018100702 10800 3600 1209600 3600 ) 1472 uri.arpa. 3600 IN RRSIG NSEC 8 2 3600 ( 1473 20181028142623 20181007205525 47155 uri.arpa. 1474 eEC4w/oXLR1Epwgv4MBiDtSBsXhqrJVvJWUpbX8XpetAvD35bxwNCUTi 1475 /pAJVUXefegWeiriD2rkTgCBCMmn7YQIm3gdR+HjY/+o3BXNQnz97f+e 1476 HAE9EDDzoNVfL1PyV/2fde9tDeUuAGVVwmD399NGq9jWYMRpyri2kysr q/g= ) 1477 uri.arpa. 86400 IN RRSIG NS 8 2 86400 ( 1478 20181028172020 20181007175821 47155 uri.arpa. 1479 ATyV2A2A8ZoggC+68u4GuP5MOUuR+2rr3eWOkEU55zAHld/7FiBxl4ln 1480 4byJYy7NudUwlMOEXajqFZE7DVl8PpcvrP3HeeGaVzKqaWj+aus0jbKF 1481 Bsvs2b1qDZemBfkz/IfAhUTJKnto0vSUicJKfItu0GjyYNJCz2CqEuGD Wxc= ) 1482 uri.arpa. 600 IN RRSIG MX 8 2 600 ( 1483 20181028170556 20181007175821 47155 uri.arpa. 1484 e7/r3KXDohX1lyVavetFFObp8fB8aXT76HnN9KCQDxSnSghNM83UQV0t 1485 lTtD8JVeN1mCvcNFZpagwIgB7XhTtm6Beur/m5ES+4uSnVeS6Q66HBZK 1486 A3mR95IpevuVIZvvJ+GcCAQpBo6KRODYvJ/c/ZG6sfYWkZ7qg/Em5/+3 4UI= ) 1487 uri.arpa. 3600 IN RRSIG DNSKEY 8 2 3600 ( 1488 20181028152832 20181007175821 15796 uri.arpa. 1489 nzpbnh0OqsgBBP8St28pLvPEQ3wZAUdEBuUwil+rtjjWlYYiqjPxZ286 1490 XF4Rq1usfV5x71jZz5IqswOaQgia91ylodFpLuXD6FTGs2nXGhNKkg1V 1491 chHgtwj70mXU72GefVgo8TxrFYzxuEFP5ZTP92t97FVWVVyyFd86sbbR 1492 6DZj3uA2wEvqBVLECgJLrMQ9Yy7MueJl3UA4h4E6zO2JY9Yp0W9woq0B 1493 dqkkwYTwzogyYffPmGAJG91RJ2h6cHtFjEZe2MnaY2glqniZ0WT9vXXd 1494 uFPm0KD9U77Ac+ZtctAF9tsZwSdAoL365E2L1usZbA+K0BnPPqGFJRJk 1495 5R0A1w== ) 1496 uri.arpa. 3600 IN RRSIG DNSKEY 8 2 3600 ( 1497 20181028152832 20181007175821 55480 uri.arpa. 1498 lWtQV/5szQjkXmbcD47/+rOW8kJPksRFHlzxxmzt906+DBYyfrH6uq5X 1499 nHvrUlQO6M12uhqDeL+bDFVgqSpNy+42/OaZvaK3J8EzPZVBHPJykKMV 1500 63T83aAiJrAyHzOaEdmzLCpalqcEE2ImzlLHSafManRfJL8Yuv+JDZFj 1501 2WDWfEcUuwkmIZWX11zxp+DxwzyUlRl7x4+ok5iKZWIg5UnBAf6B8T75 1502 WnXzlhCw3F2pXI0a5LYg71L3Tp/xhjN6Yy9jGlIRf5BjB59X2zra3a2R 1503 PkI09SSnuEwHyF1mDaV5BmQrLGRnCjvwXA7ho2m+vv4SP5dUdXf+GTeA 1504 1HeBfw== ) 1505 uri.arpa. 3600 IN RRSIG SOA 8 2 3600 ( 1506 20181029114753 20181008222815 47155 uri.arpa. 1507 qn8yBNoHDjGdT79U2Wu9IIahoS0YPOgYP8lG+qwPcrZ1BwGiHywuoUa2 1508 Mx6BWZlg+HDyaxj2iOmox+IIqoUHhXUbO7IUkJFlgrOKCgAR2twDHrXu 1509 9BUQHy9SoV16wYm3kBTEPyxW5FFm8vcdnKAF7sxSY8BbaYNpRIEjDx4A JUc= ) 1510 uri.arpa. 3600 IN NSEC ftp.uri.arpa. NS SOA ( 1511 MX RRSIG NSEC DNSKEY ) 1512 uri.arpa. 86400 IN NS a.iana-servers.net. 1513 uri.arpa. 86400 IN NS b.iana-servers.net. 1514 uri.arpa. 86400 IN NS c.iana-servers.net. 1515 uri.arpa. 86400 IN NS ns2.lacnic.net. 1516 uri.arpa. 86400 IN NS sec3.apnic.net. 1517 uri.arpa. 600 IN MX 10 pechora.icann.org. 1518 uri.arpa. 3600 IN DNSKEY 256 3 8 ( 1519 AwEAAcBi7tSart2J599zbYWspMNGN70IBWb4ziqyQYH9MTB/VCz6WyUK 1520 uXunwiJJbbQ3bcLqTLWEw134B6cTMHrZpjTAb5WAwg4XcWUu8mdcPTiL 1521 Bl6qVRlRD0WiFCTzuYUfkwsh1Rbr7rvrxSQhF5rh71zSpwV5jjjp65Wx 1522 SdJjlH0B ) 1523 uri.arpa. 3600 IN DNSKEY 257 3 8 ( 1524 AwEAAbNVv6ulgRdO31MtAehz7j3ALRjwZglWesnzvllQl/+hBRZr9QoY 1525 cO2I+DkO4Q1NKxox4DUIxj8SxPO3GwDuOFR9q2/CFi2O0mZjafbdYtWc 1526 3zSdBbi3q0cwCIx7GuG9eqlL+pg7mdk9dgdNZfHwB0LnqTD8ebLPsrO/ 1527 Id7kBaiqYOfMlZnh2fp+2h6OOJZHtY0DK1UlssyB5PKsE0tVzo5s6zo9 1528 iXKe5u+8WTMaGDY49vG80JPAKE7ezMiH/NZcUMiE0PRZ8D3foq2dYuS5 1529 ym+vA83Z7v8A+Rwh4UGnjxKB8zmr803V0ASAmHz/gwH5Vb0nH+LObwFt 1530 l3wpbp+Wpm8= ) 1531 uri.arpa. 3600 IN DNSKEY 257 3 8 ( 1532 AwEAAbwnFTakCvaUKsXji4mgmxZUJi1IygbnGahbkmFEa0L16J+TchKR 1533 wcgzVfsxUGa2MmeA4hgkAooC3uy+tTmoMsgy8uq/JAj24DjiHzd46LfD 1534 FK/qMidVqFpYSHeq2Vv5ojkuIsx4oe4KsafGWYNOczKZgH5loGjN2aJG 1535 mrIm++XCphOskgCsQYl65MIzuXffzJyxlAuts+ecAIiVeqRaqQfr8LRU 1536 7wIsLxinXirprtQrbor+EtvlHp9qXE6ARTZDzf4jvsNpKvLFZtmxzFf3 1537 e/UJz5eHjpwDSiZL7xE8aE1o1nGfPtJx9ZnB3bapltaJ5wY+5XOCKgY0 1538 xmJVvNQlwdE= ) 1539 ftp.uri.arpa. 3600 IN RRSIG NSEC 8 3 3600 ( 1540 20181028080856 20181007175821 47155 uri.arpa. 1541 HClGAqPxzkYkAT7Q/QNtQeB6YrkP6EPOef+9Qo5/2zngwAewXEAQiyF9 1542 jD1USJiroM11QqBS3v3aIdW/LXORs4Ez3hLcKNO1cKHsOuWAqzmE+BPP 1543 Arfh8N95jqh/q6vpaB9UtMkQ53tM2fYU1GszOLN0knxbHgDHAh2axMGH lqM= ) 1544 ftp.uri.arpa. 604800 IN RRSIG NAPTR 8 3 604800 ( 1545 20181028103644 20181007205525 47155 uri.arpa. 1546 WoLi+vZzkxaoLr2IGZnwkRvcDf6KxiWQd1WZP/U+AWnV+7MiqsWPZaf0 1547 9toRErerGoFOiOASNxZjBGJrRgjmavOM9U+LZSconP9zrNFd4dIu6kp5 1548 YxlQJ0uHOvx1ZHFCj6lAt1ACUIw04ZhMydTmi27c8MzEOMepvn7iH7r7 k7k= ) 1549 ftp.uri.arpa. 3600 IN NSEC http.uri.arpa. NAPTR ( 1550 RRSIG NSEC ) 1551 ftp.uri.arpa. 604800 IN NAPTR 0 0 "" "" ( 1552 "!^ftp://([^:/?#]*).*$!\\1!i" . ) 1553 http.uri.arpa. 3600 IN RRSIG NSEC 8 3 3600 ( 1554 20181029010647 20181007175821 47155 uri.arpa. 1555 U03NntQ73LHWpfLmUK8nMsqkwVsOGW2KdsyuHYAjqQSZvKbtmbv7HBmE 1556 H1+Ii3Z+wtfdMZBy5aC/6sHdx69BfZJs16xumycMlAy6325DKTQbIMN+ 1557 ift9GrKBC7cgCd2msF/uzSrYxxg4MJQzBPvlkwXnY3b7eJSlIXisBIn7 3b8= ) 1558 http.uri.arpa. 604800 IN RRSIG NAPTR 8 3 604800 ( 1559 20181029011815 20181007205525 47155 uri.arpa. 1560 T7mRrdag+WSmG+n22mtBSQ/0Y3v+rdDnfQV90LN5Fq32N5K2iYFajF7F 1561 Tp56oOznytfcL4fHrqOE0wRc9NWOCCUec9C7Wa1gJQcllEvgoAM+L6f0 1562 RsEjWq6+9jvlLKMXQv0xQuMX17338uoD/xiAFQSnDbiQKxwWMqVAimv5 7Zs= ) 1563 http.uri.arpa. 3600 IN NSEC mailto.uri.arpa. NAPTR ( 1564 RRSIG NSEC ) 1565 http.uri.arpa. 604800 IN NAPTR 0 0 "" "" ( 1566 "!^http://([^:/?#]*).*$!\\1!i" . ) 1568 mailto.uri.arpa. 3600 IN RRSIG NSEC 8 3 3600 ( 1569 20181028110727 20181007175821 47155 uri.arpa. 1570 GvxzVL85rEukwGqtuLxek9ipwjBMfTOFIEyJ7afC8HxVMs6mfFa/nEM/ 1571 IdFvvFg+lcYoJSQYuSAVYFl3xPbgrxVSLK125QutCFMdC/YjuZEnq5cl 1572 fQciMRD7R3+znZfm8d8u/snLV9w4D+lTBZrJJUBe1Efc8vum5vvV7819 ZoY= ) 1573 mailto.uri.arpa. 604800 IN RRSIG NAPTR 8 3 604800 ( 1574 20181028141825 20181007205525 47155 uri.arpa. 1575 MaADUgc3fc5v++M0YmqjGk3jBdfIA5RuP62hUSlPsFZO4k37erjIGCfF 1576 j+g84yc+QgbSde0PQHszl9fE/+SU5ZXiS9YdcbzSZxp2erFpZOTchrpg 1577 916T4vx6i59scodjb0l6bDyZ+mtIPrc1w6b4hUyOUTsDQoAJYxdfEuMg Vy4= ) 1578 mailto.uri.arpa. 3600 IN NSEC urn.uri.arpa. NAPTR ( 1579 RRSIG NSEC ) 1580 mailto.uri.arpa. 604800 IN NAPTR 0 0 "" "" ( 1581 "!^mailto:(.*)@(.*)$!\\2!i" . ) 1582 urn.uri.arpa. 3600 IN RRSIG NSEC 8 3 3600 ( 1583 20181028123243 20181007175821 47155 uri.arpa. 1584 Hgsw4Deops1O8uWyELGe6hpR/OEqCnTHvahlwiQkHhO5CSEQrbhmFAWe 1585 UOkmGAdTEYrSz+skLRQuITRMwzyFf4oUkZihGyhZyzHbcxWfuDc/Pd/9 1586 DSl56gdeBwy1evn5wBTms8yWQVkNtphbJH395gRqZuaJs3LD/qTyJ5Dp LvA= ) 1587 urn.uri.arpa. 604800 IN RRSIG NAPTR 8 3 604800 ( 1588 20181029071816 20181007205525 47155 uri.arpa. 1589 ALIZD0vBqAQQt40GQ0Efaj8OCyE9xSRJRdyvyn/H/wZVXFRFKrQYrLAS 1590 D/K7q6CMTOxTRCu2J8yes63WJiaJEdnh+dscXzZkmOg4n5PsgZbkvUSW 1591 BiGtxvz5jNncM0xVbkjbtByrvJQAO1cU1mnlDKe1FmVB1uLpVdA9Ib4J hMU= ) 1592 urn.uri.arpa. 3600 IN NSEC uri.arpa. NAPTR RRSIG ( 1593 NSEC ) 1594 urn.uri.arpa. 604800 IN NAPTR 0 0 "" "" ( 1595 "/urn:([^:]+)/\\1/i" . ) 1596 uri.arpa. 3600 IN SOA sns.dns.icann.org. ( 1597 noc.dns.icann.org. 2018100702 10800 3600 1209600 3600 ) 1598 ;; Query time: 66 msec 1599 ;; SERVER: 192.0.32.132#53(192.0.32.132) 1600 ;; WHEN: Sun Oct 21 20:39:28 UTC 2018 1601 ;; XFR size: 34 records (messages 1, bytes 3941) 1602 uri.arpa. 3600 IN ZONEMD 2018100702 1 1 ( 1603 1291b78ddf7669b1a39d014d87626b709b55774c5d7d58fa 1604 dc556439889a10eaf6f11d615900a4f996bd46279514e473 ) 1606 A.5. The ROOT-SERVERS.NET Zone 1608 The ROOT-SERVERS.NET zone retrieved 2018-10-21. 1610 root-servers.net. 3600000 IN SOA a.root-servers.net. ( 1611 nstld.verisign-grs.com. 2018091100 14400 7200 1209600 3600000 ) 1612 root-servers.net. 3600000 IN NS a.root-servers.net. 1613 root-servers.net. 3600000 IN NS b.root-servers.net. 1614 root-servers.net. 3600000 IN NS c.root-servers.net. 1615 root-servers.net. 3600000 IN NS d.root-servers.net. 1616 root-servers.net. 3600000 IN NS e.root-servers.net. 1617 root-servers.net. 3600000 IN NS f.root-servers.net. 1618 root-servers.net. 3600000 IN NS g.root-servers.net. 1619 root-servers.net. 3600000 IN NS h.root-servers.net. 1620 root-servers.net. 3600000 IN NS i.root-servers.net. 1621 root-servers.net. 3600000 IN NS j.root-servers.net. 1622 root-servers.net. 3600000 IN NS k.root-servers.net. 1623 root-servers.net. 3600000 IN NS l.root-servers.net. 1624 root-servers.net. 3600000 IN NS m.root-servers.net. 1625 a.root-servers.net. 3600000 IN AAAA 2001:503:ba3e::2:30 1626 a.root-servers.net. 3600000 IN A 198.41.0.4 1627 b.root-servers.net. 3600000 IN MX 20 mail.isi.edu. 1628 b.root-servers.net. 3600000 IN AAAA 2001:500:200::b 1629 b.root-servers.net. 3600000 IN A 199.9.14.201 1630 c.root-servers.net. 3600000 IN AAAA 2001:500:2::c 1631 c.root-servers.net. 3600000 IN A 192.33.4.12 1632 d.root-servers.net. 3600000 IN AAAA 2001:500:2d::d 1633 d.root-servers.net. 3600000 IN A 199.7.91.13 1634 e.root-servers.net. 3600000 IN AAAA 2001:500:a8::e 1635 e.root-servers.net. 3600000 IN A 192.203.230.10 1636 f.root-servers.net. 3600000 IN AAAA 2001:500:2f::f 1637 f.root-servers.net. 3600000 IN A 192.5.5.241 1638 g.root-servers.net. 3600000 IN AAAA 2001:500:12::d0d 1639 g.root-servers.net. 3600000 IN A 192.112.36.4 1640 h.root-servers.net. 3600000 IN AAAA 2001:500:1::53 1641 h.root-servers.net. 3600000 IN A 198.97.190.53 1642 i.root-servers.net. 3600000 IN MX 10 mx.i.root-servers.org. 1643 i.root-servers.net. 3600000 IN AAAA 2001:7fe::53 1644 i.root-servers.net. 3600000 IN A 192.36.148.17 1645 j.root-servers.net. 3600000 IN AAAA 2001:503:c27::2:30 1646 j.root-servers.net. 3600000 IN A 192.58.128.30 1647 k.root-servers.net. 3600000 IN AAAA 2001:7fd::1 1648 k.root-servers.net. 3600000 IN A 193.0.14.129 1649 l.root-servers.net. 3600000 IN AAAA 2001:500:9f::42 1650 l.root-servers.net. 3600000 IN A 199.7.83.42 1651 m.root-servers.net. 3600000 IN AAAA 2001:dc3::35 1652 m.root-servers.net. 3600000 IN A 202.12.27.33 1653 root-servers.net. 3600000 IN SOA a.root-servers.net. ( 1654 nstld.verisign-grs.com. 2018091100 14400 7200 1209600 3600000 ) 1655 root-servers.net. 3600000 IN ZONEMD 2018091100 1 1 ( 1656 f1ca0ccd91bd5573d9f431c00ee0101b2545c97602be0a97 1657 8a3b11dbfc1c776d5b3e86ae3d973d6b5349ba7f04340f79 ) 1659 Appendix B. Implementation Status 1661 RFC Editor: Please retain this section upon publication. 1663 This section records the status of known implementations of the 1664 protocol defined by this specification at the time of publication, 1665 and is inspired by the concepts described in RFC7942. 1667 Please note that the listing of any individual implementation here 1668 does not imply endorsement by the IETF. Furthermore, no effort has 1669 been spent to verify the information presented here that was supplied 1670 by IETF contributors. This is not intended as, and must not be 1671 construed to be, a catalog of available implementations or their 1672 features. Readers are advised to note that other implementations may 1673 exist. 1675 B.1. Authors' Implementation 1677 The authors have an open source implementation in C, using the ldns 1678 library [ldns-zone-digest]. This implementation is able to perform 1679 the following functions: 1681 o Read an input zone and output a zone with the ZONEMD placeholder. 1683 o Compute zone digest over signed zone and update the ZONEMD record. 1685 o Re-compute DNSSEC signature over the ZONEMD record. 1687 o Verify the zone digest from an input zone. 1689 This implementation does not: 1691 o Perform DNSSEC validation of the ZONEMD record during 1692 verification. 1694 B.2. Shane Kerr's Implementation 1696 Shane Kerr wrote an implementation of this specification during the 1697 IETF 102 hackathon [ZoneDigestHackathon]. This implementation is in 1698 Python and is able to perform the following functions: 1700 o Read an input zone and output a zone with ZONEMD record. 1702 o Verify the zone digest from an input zone. 1704 o Output the ZONEMD record in its defined presentation format. 1706 This implementation does not: 1708 o Re-compute DNSSEC signature over the ZONEMD record. 1710 o Perform DNSSEC validation of the ZONEMD record. 1712 B.3. NIC Chile Labs Implementation 1714 NIC Chile Labs wrote an implementation of this specification as part 1715 of "dns-tools" suite [DnsTools], which besides digesting, can also 1716 sign and verify zones. This implementation is in Go and is able to 1717 perform the following functions: 1719 o Compute zone digest over signed zone and update the ZONEMD record. 1721 o Verify the zone digest from an input zone. 1723 o Perform DNSSEC validation of the ZONEMD record during 1724 verification. 1726 o Re-compute DNSSEC signature over the ZONEMD record. 1728 Authors' Addresses 1730 Duane Wessels 1731 Verisign 1732 12061 Bluemont Way 1733 Reston, VA 20190 1735 Phone: +1 703 948-3200 1736 Email: dwessels@verisign.com 1737 URI: https://verisign.com 1739 Piet Barber 1740 Verisign 1741 12061 Bluemont Way 1742 Reston, VA 20190 1744 Phone: +1 703 948-3200 1745 Email: pbarber@verisign.com 1746 URI: https://verisign.com 1748 Matt Weinberg 1749 Amazon 1751 Email: matweinb@amazon.com 1752 URI: https://amazon.com 1753 Warren Kumari 1754 Google 1755 1600 Amphitheatre Parkway 1756 Mountain View, CA 94043 1758 Email: warren@kumari.net 1760 Wes Hardaker 1761 USC/ISI 1762 P.O. Box 382 1763 Davis, CA 95617 1765 Email: ietf@hardakers.net