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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 2, 2021 M. Weinberg 6 Amazon 7 W. Kumari 8 Google 9 W. Hardaker 10 USC/ISI 11 September 29, 2020 13 Message Digest for DNS Zones 14 draft-ietf-dnsop-dns-zone-digest-12 16 Abstract 18 This document describes a protocol and new DNS Resource Record that 19 provides a cryptographic message digest over DNS zone data. The 20 ZONEMD Resource Record conveys the digest data in the zone itself. 21 When a zone publisher includes a ZONEMD record, recipients can verify 22 the zone contents for accuracy and completeness. This provides 23 assurance that received zone data matches published data, regardless 24 of how the zone data has been transmitted and received. 26 ZONEMD does not replace DNSSEC. Whereas DNSSEC protects individual 27 RRSets (DNS data with fine granularity), ZONEMD protects a zone's 28 data as a whole, whether consumed by authoritative name servers, 29 recursive name servers, or any other applications. 31 As specified herein, ZONEMD is impractical for large, dynamic zones 32 due to the time and resources required for digest calculation. 33 However, The ZONEMD record is extensible so that new digest schemes 34 may be added in the future to 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 April 2, 2021. 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. Alternative Approaches . . . . . . . . . . . . . . . . . 4 73 1.3. Design Overview . . . . . . . . . . . . . . . . . . . . . 6 74 1.4. Use Cases . . . . . . . . . . . . . . . . . . . . . . . . 6 75 1.4.1. Root Zone . . . . . . . . . . . . . . . . . . . . . . 6 76 1.4.2. Providers, Secondaries, and Anycast . . . . . . . . . 6 77 1.4.3. Response Policy Zones . . . . . . . . . . . . . . . . 7 78 1.4.4. Centralized Zone Data Service . . . . . . . . . . . . 7 79 1.4.5. General Purpose Comparison Check . . . . . . . . . . 7 80 1.5. Terminology . . . . . . . . . . . . . . . . . . . . . . . 7 81 2. The ZONEMD Resource Record . . . . . . . . . . . . . . . . . 7 82 2.1. Non-apex ZONEMD Records . . . . . . . . . . . . . . . . . 8 83 2.2. ZONEMD RDATA Wire Format . . . . . . . . . . . . . . . . 8 84 2.2.1. The Serial Field . . . . . . . . . . . . . . . . . . 8 85 2.2.2. The Scheme Field . . . . . . . . . . . . . . . . . . 9 86 2.2.3. The Hash Algorithm Field . . . . . . . . . . . . . . 9 87 2.2.4. The Digest Field . . . . . . . . . . . . . . . . . . 9 88 2.3. ZONEMD Presentation Format . . . . . . . . . . . . . . . 10 89 2.4. ZONEMD Example . . . . . . . . . . . . . . . . . . . . . 10 90 3. Calculating the Digest . . . . . . . . . . . . . . . . . . . 10 91 3.1. Add ZONEMD Placeholder . . . . . . . . . . . . . . . . . 10 92 3.2. Optionally Sign the Zone . . . . . . . . . . . . . . . . 11 93 3.3. Scheme-Specific Processing . . . . . . . . . . . . . . . 11 94 3.3.1. The SIMPLE Scheme . . . . . . . . . . . . . . . . . . 11 95 3.3.1.1. SIMPLE Scheme Inclusion/Exclusion Rules . . . . . 11 96 3.3.1.2. SIMPLE Scheme Digest Calculation . . . . . . . . 12 97 3.4. Update ZONEMD RR . . . . . . . . . . . . . . . . . . . . 12 98 4. Verifying Zone Digest . . . . . . . . . . . . . . . . . . . . 12 99 5. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 14 100 5.1. ZONEMD RRtype . . . . . . . . . . . . . . . . . . . . . . 14 101 5.2. ZONEMD Scheme . . . . . . . . . . . . . . . . . . . . . . 14 102 5.3. ZONEMD Hash Algorithm . . . . . . . . . . . . . . . . . . 15 103 6. Security Considerations . . . . . . . . . . . . . . . . . . . 15 104 6.1. Attacks Against the Zone Digest . . . . . . . . . . . . . 16 105 6.2. DNSSESC Timing Considerations . . . . . . . . . . . . . . 16 106 6.3. Attacks Utilizing ZONEMD Queries . . . . . . . . . . . . 16 107 6.4. Resilience and Fragility . . . . . . . . . . . . . . . . 17 108 7. Performance Considerations . . . . . . . . . . . . . . . . . 17 109 7.1. SIMPLE SHA384 . . . . . . . . . . . . . . . . . . . . . . 17 110 8. Privacy Considerations . . . . . . . . . . . . . . . . . . . 18 111 9. Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . 18 112 10. Change Log . . . . . . . . . . . . . . . . . . . . . . . . . 18 113 11. References . . . . . . . . . . . . . . . . . . . . . . . . . 25 114 11.1. Normative References . . . . . . . . . . . . . . . . . . 25 115 11.2. Informative References . . . . . . . . . . . . . . . . . 25 116 Appendix A. Example Zones With Digests . . . . . . . . . . . . . 28 117 A.1. Simple EXAMPLE Zone . . . . . . . . . . . . . . . . . . . 28 118 A.2. Complex EXAMPLE Zone . . . . . . . . . . . . . . . . . . 28 119 A.3. EXAMPLE Zone with multiple digests . . . . . . . . . . . 29 120 A.4. The URI.ARPA Zone . . . . . . . . . . . . . . . . . . . . 30 121 A.5. The ROOT-SERVERS.NET Zone . . . . . . . . . . . . . . . . 33 122 Appendix B. Implementation Status . . . . . . . . . . . . . . . 35 123 B.1. Authors' Implementation . . . . . . . . . . . . . . . . . 35 124 B.2. Shane Kerr's Implementation . . . . . . . . . . . . . . . 35 125 B.3. NIC Chile Labs Implementation . . . . . . . . . . . . . . 36 126 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 36 128 1. Introduction 130 In the DNS, a zone is the collection of authoritative resource 131 records (RRs) sharing a common origin ([RFC8499]). Zones are often 132 stored as files in the so-called master file format [RFC1034]. Zones 133 are generally distributed among name servers using the AXFR (zone 134 transfer [RFC5936]), and IXFR (incremental zone transfer [RFC1995]) 135 protocols. They can also be distributed outside of the DNS, with any 136 file transfer protocol such as FTP, HTTP, and rsync, or even as email 137 attachments. Currently there is no standard way to verify the 138 authenticity of a stand-alone zone. 140 This document specifies an RR type that provides a cryptographic 141 message digest of the data in a zone. It allows a receiver of the 142 zone to verify the zone's integrity, and when used in combination 143 with DNSSEC, its authenticity. The digest RR is a part of the zone 144 itself, allowing verification of the zone, no matter how it is 145 transmitted. The digest uses the wire format of zone data in a 146 canonical ordering. Thus, it is independent of presentation format, 147 such as whitespace, capitalization, and comments. 149 This specification is OPTIONAL to implement by both publishers and 150 consumers of zone data. 152 DNSSEC provides three strong security guarantees relevant to this 153 protocol: 155 1. whether or not to expect DNSSEC records in the zone, 157 2. whether or not to expect a ZONEMD record in a signed zone, and 159 3. whether or not the ZONEMD record has been altered since it was 160 signed. 162 1.1. Motivation 164 The motivation for this protocol enhancement is the desire to verify 165 the authenticity of a stand-alone zone, regardless of how it is 166 transmitted. A consumer of zone data should be able to verify that 167 the data is as-published by the zone operator. 169 1.2. Alternative Approaches 171 One approach to preventing data tampering and corruption is to secure 172 the distribution channel. The DNS has a number of features that are 173 already used for channel security. Perhaps the most widely used is 174 DNS transaction signatures (TSIG [RFC2845]). TSIG uses shared secret 175 keys and a message digest to protect individual query and response 176 messages. It is generally used to authenticate and validate UPDATE 177 [RFC2136], AXFR [RFC5936], and IXFR [RFC1995] messages. 179 DNS Request and Transaction Signatures (SIG(0) [RFC2931]) is another 180 protocol extension that authenticates individual DNS transactions. 181 Whereas SIG records normally cover specific RR types, SIG(0) is used 182 to sign an entire DNS message. Unlike TSIG, SIG(0) uses public key 183 cryptography rather than shared secrets. 185 The Transport Layer Security protocol suite also provides channel 186 security. One can easily imagine the distribution of zones over 187 HTTPS-enabled web servers, as well as DNS-over-HTTPS [RFC8484], and 188 perhaps even a future version of DNS-over-TLS ([RFC7858]). 190 Unfortunately, the protections provided by these channel security 191 techniques are (in practice) ephemeral and are not retained after the 192 data transfer is complete. They ensure that the client receives the 193 data from the expected server, and that the data sent by the server 194 is not modified during transmission. However, they do not guarantee 195 that the server transmits the data as originally published, and do 196 not provide any methods to verify data that is read after 197 transmission is complete. For example, a name server loading saved 198 zone data upon restart cannot guarantee that the on-disk data has not 199 been modified. Such modification could be the result of an 200 accidental corruption of the file, or perhaps an incompletely saved 201 file [disk-full-failure]. For these reasons, it is preferable to 202 secure the data itself. 204 Why not simply rely on DNSSEC, which provides certain data security 205 guarantees? For zones that are signed, a recipient could validate 206 all of the signed RRSets. Additionally, denial-of-existence records 207 prove that RRSets have not been added or removed. However, 208 delegations (non-apex NS records) are not signed by DNSSEC, and 209 neither are any glue records. ZONEMD protects the integrity of 210 delegation, glue, and other records that are not otherwise covered by 211 DNSSEC. Furthermore, zones that employ NSEC3 with opt-out are 212 susceptible to the removal or addition of names between the signed 213 nodes. Whereas DNSSEC is primarily protects consumers of DNS 214 response messages, this protocol protects consumers of zones. 216 There are existing tools and protocols that provide data security, 217 such as OpenPGP [RFC4880] and S/MIME [RFC5751]. In fact, the 218 internic.net site publishes PGP signatures alongside the root zone 219 and other files available there. However, this is a detached 220 signature with no strong association to the corresponding zone file 221 other than its timestamp. Non-detached signatures are, of course, 222 possible, but these necessarily change the format of the file being 223 distributed; a zone signed with OpenPGP or S/MIME no longer looks 224 like a DNS zone and could not directly be loaded into a name server. 225 Once loaded the signature data is lost, so it cannot be further 226 propagated. 228 It seems the desire for data security in DNS zones was envisioned as 229 far back as 1997. [RFC2065] is an obsoleted specification of the 230 first generation DNSSEC Security Extensions. It describes a zone 231 transfer signature, identified as the AXFR SIG, which is similar to 232 the technique proposed by this document. That is, it proposes 233 ordering all (signed) RRSets in a zone, hashing their contents, and 234 then signing the zone hash. The AXFR SIG is described only for use 235 during zone transfers. It did not postulate the need to validate 236 zone data distributed outside of the DNS. Furthermore, its 237 successor, [RFC2535], omits the AXFR SIG, while at the same time 238 introducing an IXFR SIG. 240 1.3. Design Overview 242 This document specifies a new Resource Record type to convey a 243 message digest of the content of a zone. The digest is calculated at 244 the time of zone publication. If the zone is signed with DNSSEC, any 245 modifications of the digest can be detected. The procedures for 246 digest calculation and DNSSEC signing are similar. Both require data 247 to be processed in a well-defined order and format. It may be 248 possible to perform DNSSEC signing and digest calculation in 249 parallel. 251 The zone digest is designed to be used on zones that have infrequent 252 updates. As specified herein, the digest is re-calculated over the 253 entire zone content each time. This specification does not provide 254 an efficient mechanism for updating the digest on incremental updates 255 of zone data. It is, however, extensible so future schemes to 256 support incremental zone digest algorithms (e.g. using Merkle trees) 257 can be accommodated. 259 It is expected that verification of a zone digest will be implemented 260 in name server software. That is, a name server can verify the zone 261 data it was given and refuse to serve a zone which fails 262 verification. For signed zones, the name server needs a trust anchor 263 to perform DNSSEC validation. For signed non-root zones, the name 264 server may need to send queries to validate a chain of trust. Digest 265 verification could also be performed externally. 267 1.4. Use Cases 269 1.4.1. Root Zone 271 The root zone [InterNIC] is one of the most widely distributed DNS 272 zone on the Internet, served by more than 1000 separate instances 273 [RootServers] at the time of this writing. Additionally, many 274 organizations configure their own name servers to serve the root zone 275 locally. Reasons for doing so include privacy and reduced access 276 time. [RFC8806] describes one way to do this. As the root zone 277 spreads beyond its traditional deployment boundaries, the 278 verification of the completeness of the zone contents becomes more 279 important. 281 1.4.2. Providers, Secondaries, and Anycast 283 Since its very early days, the developers of the DNS recognized the 284 importance of secondary name servers and service diversity. However, 285 modern DNS service has complex provisioning which includes multiple 286 third-party providers and hundreds of anycast instances. Instead of 287 a simple primary-to-secondary zone distribution system, today it is 288 possible to have multiple levels, multiple parties, and multiple 289 protocols involved in the distribution of zone data. This complexity 290 introduces new places for problems to arise. The zone digest 291 protects the integrity of data that flows through such systems. 293 1.4.3. Response Policy Zones 295 DNS Response Policy Zones is "a method of expressing DNS response 296 policy information inside specially constructed DNS zones..." [RPZ]. 297 A number of companies provide RPZ feeds, which are consumed by name 298 server and firewall products. While RPZ zones can be signed with 299 DNSSEC, the data is not queried directly, and would not be subject to 300 DNSSEC validation. 302 1.4.4. Centralized Zone Data Service 304 ICANN operates the Centralized Zone Data Service [CZDS], which is a 305 repository of top-level domain zone files. Users that have been 306 granted access are then able to download zone data. Adding a zone 307 digest to these would provide CZDS users with assurances that the 308 data has not been modified between origination and retrieval. ZONEMD 309 could be added to CZDS zone data independently of the zone served by 310 production name servers. 312 1.4.5. General Purpose Comparison Check 314 Since the zone digest calculation does not depend on presentation 315 format, it could be used to compare multiple copies of a zone 316 received from different sources, or copies generated by different 317 processes. 319 1.5. Terminology 321 The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", 322 "SHOULD", "SHOULD NOT", "RECOMMENDED", "NOT RECOMMENDED", "MAY", and 323 "OPTIONAL" in this document are to be interpreted as described in BCP 324 14 [RFC2119] [RFC8174] when, and only when, they appear in all 325 capitals, as shown here. 327 The terms Private Use, Reserved, Unassigned, and Specification 328 Required are to be interpreted as defined in [RFC8126]. 330 2. The ZONEMD Resource Record 332 This section describes the ZONEMD Resource Record, including its 333 fields, wire format, and presentation format. The Type value for the 334 ZONEMD RR is 63. The ZONEMD RR is class independent. The RDATA of 335 the resource record consists of four fields: Serial, Scheme, Hash 336 Algorithm, and Digest. 338 A zone MAY contain multiple ZONEMD RRs to support algorithm agility 339 [RFC7696] and rollovers. When multiple ZONEMD RRs are present, each 340 must specify a unique Scheme and Hash Algorithm tuple. It is 341 RECOMMENDED that a zone include only one ZONEMD RR, unless the zone 342 publisher is in the process of transitioning to a new Scheme or Hash 343 Algorithm. 345 2.1. Non-apex ZONEMD Records 347 This document specifies ZONEMD RRs located at the zone apex. Non- 348 apex ZONEMD RRs are not forbidden, but have no meaning in this 349 specification. Non-apex ZONEMD RRs MUST NOT be used for 350 verification. 352 During digest calculation, non-apex ZONEMD RRs are treated as 353 ordinary RRs. They are digested as-is and the RR is not replaced by 354 a placeholder RR. 356 Unless explicitly stated otherwise, "ZONEMD" always refers to apex 357 records throughout this document. 359 2.2. ZONEMD RDATA Wire Format 361 The ZONEMD RDATA wire format is encoded as follows: 363 1 1 1 1 1 1 1 1 1 1 2 2 2 2 2 2 2 2 2 2 3 3 364 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 1 365 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 366 | Serial | 367 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 368 | Scheme |Hash Algorithm | | 369 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | 370 | Digest | 371 / / 372 / / 373 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 375 2.2.1. The Serial Field 377 The Serial field is a 32-bit unsigned integer in network byte order. 378 It is the serial number from the zone's SOA record ([RFC1035] section 379 3.3.13) for which the zone digest was generated. 381 It is included here to clearly bind the ZONEMD RR to a particular 382 version of the zone's content. Without the serial number, a stand- 383 alone ZONEMD digest has no obvious association to any particular 384 instance of a zone. 386 2.2.2. The Scheme Field 388 The Scheme field is an 8-bit unsigned integer that identifies the 389 methods by which data is collated and presented as input to the 390 hashing function. 392 Herein, SIMPLE, with value 1, is the only standardized Scheme defined 393 for ZONEMD records and it MUST be implemented. The Scheme registry 394 is further described in Section 5. 396 Scheme values 240-254 are allocated for Private Use. 398 2.2.3. The Hash Algorithm Field 400 The Hash Algorithm field is an 8-bit unsigned integer that identifies 401 the cryptographic hash algorithm used to construct the digest. 403 Herein, SHA384 [RFC6234], with value 1, is the only standardized Hash 404 Algorithm defined for ZONEMD records that MUST be implemented. When 405 SHA384 is used, the size of the Digest field is 48 octets. The 406 result of the SHA384 digest algorithm MUST NOT be truncated, and the 407 entire 48 octet digest is published in the ZONEMD record. 409 SHA512 [RFC6234], with Hash Algorithm value 2, is also defined for 410 ZONEMD records, and SHOULD be implemented. When SHA512 is used, the 411 size of the Digest field is 64 octets. The result of the SHA512 412 digest algorithm MUST NOT be truncated, and the entire 64 octet 413 digest is published in the ZONEMD record. 415 Hash Algorithm values 240-254 are allocated for Private Use. 417 The Hash Algorithm registry is further described in Section 5. 419 2.2.4. The Digest Field 421 The Digest field is a variable-length sequence of octets containing 422 the output of the hash algorithm. The length of the Digest field is 423 determined by deducting the fixed size of the Serial, Scheme, and 424 Hash Algorithm fields from the RDATA size in the ZONEMD RR header. 426 The Digest field MUST NOT be shorter than 12 octets. Digests for the 427 SHA384 and SHA512 hash algorithms specified herein are never 428 truncated. Digests for future hash algorithms MAY be truncated, but 429 MUST NOT be truncated to a length that results in less than 96-bits 430 (12 octets) of equivalent strength. 432 Section 3 describes how to calculate the digest for a zone. 433 Section 4 describes how to use the digest to verify the contents of a 434 zone. 436 2.3. ZONEMD Presentation Format 438 The presentation format of the RDATA portion is as follows: 440 The Serial field is represented as an unsigned decimal integer. 442 The Scheme field is represented as an unsigned decimal integer. 444 The Hash Algorithm field is represented as an unsigned decimal 445 integer. 447 The Digest is represented as a sequence of case-insensitive 448 hexadecimal digits. Whitespace is allowed within the hexadecimal 449 text. 451 2.4. ZONEMD Example 453 The following example shows a ZONEMD RR in presentation format: 455 example.com. 86400 IN ZONEMD 2018031500 1 1 ( 456 FEBE3D4CE2EC2FFA4BA99D46CD69D6D29711E55217057BEE 457 7EB1A7B641A47BA7FED2DD5B97AE499FAFA4F22C6BD647DE ) 459 3. Calculating the Digest 461 3.1. Add ZONEMD Placeholder 463 In preparation for calculating the zone digest, any existing ZONEMD 464 records (and covering RRSIGs) at the zone apex are first deleted. 466 Prior to calculation of the digest, and prior to signing with DNSSEC, 467 one or more placeholder ZONEMD records are added to the zone apex. 468 This ensures that denial-of-existence (NSEC, NSEC3) records are 469 created correctly if the zone is signed with DNSSEC. If placeholders 470 were not added prior to signing, the later addition of ZONEMD records 471 would also require updating the Type Bit Maps field of any apex NSEC/ 472 NSEC3 RRs, which then invalidates the calculated digest value. 474 When multiple ZONEMD RRs are published in the zone, e.g., during an 475 algorithm rollover, each MUST specify a unique Scheme and Hash 476 Algorithm tuple. 478 It is RECOMMENDED that the TTL of the ZONEMD record match the TTL of 479 the SOA. However, the TTL of the ZONEMD record may be safely ignored 480 during verification in all cases. 482 In the placeholder record, the Serial field is set to the current SOA 483 Serial. The Scheme field is set to the value for the chosen 484 collation scheme. The Hash Algorithm field is set to the value for 485 the chosen hash algorithm. Since apex ZONEMD records are excluded 486 from digest calculation, the value of the Digest field does not 487 matter at this point in the process. 489 3.2. Optionally Sign the Zone 491 Following addition of placeholder records, the zone may be signed 492 with DNSSEC. When the digest calculation is complete, and the ZONEMD 493 record is updated, the signature(s) for the ZONEMD RRSet MUST be 494 recalculated and updated as well. Therefore, the signer is not 495 required to calculate a signature over the placeholder record at this 496 step in the process, but it is harmless to do so. 498 3.3. Scheme-Specific Processing 500 Herein, only the SIMPLE collation scheme is defined. Additional 501 schemes may be defined in future updates to this document. 503 3.3.1. The SIMPLE Scheme 505 For the SIMPLE scheme, the digest is calculated over the zone as a 506 whole. This means that a change to a single RR in the zone requires 507 iterating over all RRs in the zone to recalculate the digest. SIMPLE 508 is a good choice for zones that are small and/or stable, but probably 509 not good for zones that are large and/or dynamic. 511 Calculation of a zone digest REQUIRES RRs to be processed in a 512 consistent format and ordering. This specification uses DNSSEC's 513 canonical on-the-wire RR format (without name compression) and 514 ordering as specified in Sections 6.1, 6.2, and 6.3 of [RFC4034] with 515 the additional provision that RRSets having the same owner name MUST 516 be numerically ordered, in ascending order, by their numeric RR TYPE. 518 3.3.1.1. SIMPLE Scheme Inclusion/Exclusion Rules 520 When iterating over records in the zone, the following inclusion/ 521 exclusion rules apply: 523 o All records in the zone, including glue records, MUST be included. 525 o Occluded data ([RFC5936] Section 3.5) MUST be included. 527 o If there are duplicate RRs with equal owner, class, type, and 528 RDATA, only one instance is included ([RFC4034] Section 6.3), and 529 the duplicates MUST be omitted. 531 o The placeholder apex ZONEMD RR(s) MUST NOT be included. 533 o If the zone is signed, DNSSEC RRs MUST be included, except: 535 o The RRSIG covering the apex ZONEMD RRSet MUST NOT be included 536 because the RRSIG will be updated after all digests have been 537 calculated. 539 3.3.1.2. SIMPLE Scheme Digest Calculation 541 A zone digest using the SIMPLE scheme is calculated by concatenating 542 all RRs in the zone, in the format and order described in 543 Section 3.3.1 subject to the inclusion/exclusion rules described in 544 Section 3.3.1.1, and then applying the chosen hash algorithm: 546 digest = hash( RR(1) | RR(2) | RR(3) | ... ) 548 where "|" denotes concatenation. 550 3.4. Update ZONEMD RR 552 The calculated zone digest is inserted into the placeholder ZONEMD 553 RR. Repeat for each digest if multiple digests are to be published. 555 If the zone is signed with DNSSEC, the RRSIG record(s) covering the 556 ZONEMD RRSet MUST then be added or updated. Because the ZONEMD 557 placeholder was added prior to signing, the zone will already have 558 the appropriate denial-of-existence (NSEC, NSEC3) records. 560 Some DNSSEC implementations (especially "online signing") might 561 update the SOA serial number whenever a new signature is made. To 562 preserve the calculated digest, generation of a ZONEMD signature MUST 563 NOT also result in a change to the SOA serial number. The ZONEMD RR 564 and the matching SOA MUST be published at the same time. 566 4. Verifying Zone Digest 568 The recipient of a zone that has a ZONEMD RR verifies the zone by 569 calculating the digest as follows. If multiple ZONEMD RRs are 570 present in the zone, e.g., during an algorithm rollover, a match 571 using any one of the recipient's supported Schemes and Hash 572 Algorithms is sufficient to verify the zone. The verifier MAY ignore 573 a ZONEMD RR if its Scheme and Hash Algorithm violates local policy. 575 1. The verifier MUST first determine whether or not to expect DNSSEC 576 records in the zone. This is done by examining locally 577 configured trust anchors, or querying for (and validating) DS RRs 578 in the parent zone. For zones that are provably insecure, or if 579 DNSSEC validation is not performed, digest verification continues 580 at step 4 below. 582 2. For zones that are provably secure, the existence of the apex 583 ZONEMD record MUST be verified. If the ZONEMD record provably 584 does not exist, digest verification cannot occur. If the ZONEMD 585 record does provably exist, but is not found in the zone, digest 586 verification MUST NOT be considered successful. 588 3. For zones that are provably secure, the SOA and ZONEMD RRSets 589 MUST have valid signatures, chaining up to a trust anchor. If 590 DNSSEC validation of the SOA or ZONEMD records fails, digest 591 verification MUST NOT be considered successful. 593 4. When multiple ZONEMD RRs are present, each MUST specify a unique 594 Scheme and Hash Algorithm tuple. If the ZONEMD RRSet contains 595 more than one RR with the same Scheme and Hash Algorithm, digest 596 verification for those ZONEMD RRs MUST NOT be considered 597 successful. 599 5. Loop over all apex ZONEMD RRs and perform the following steps: 601 A. The SOA Serial field MUST exactly match the ZONEMD Serial 602 field. If the fields do not match, digest verification MUST 603 NOT be considered successful with this ZONEMD RR. 605 B. The Scheme field MUST be checked. If the verifier does not 606 support the given scheme, verification MUST NOT be considered 607 successful with this ZONEMD RR and it SHOULD report that the 608 RR's digest could not be verified due to an unsupported 609 scheme. 611 C. The Hash Algorithm field MUST be checked. If the verifier 612 does not support the given hash algorithm, verification MUST 613 NOT be considered successful with this ZONEMD RR and it 614 SHOULD report that the RR's digest could not be verified due 615 to an unsupported algorithm. 617 D. The Digest field size MUST be checked. If the size of the 618 given Digest field is smaller than 12 octets, or if the size 619 is not equal to the size expected for the corresponding Hash 620 Algorithm, verification MUST NOT be considered successful 621 with this ZONEMD RR and the verifier SHOULD report that the 622 RR's digest could not be verified due to an incorrect digest 623 length. 625 E. The zone digest is computed over the zone data as described 626 in Section 3.3, using the Scheme and Hash Algorithm for the 627 current ZONEMD RR. 629 F. The computed digest is compared to the received digest. If 630 the two digest values match, verification is considered 631 successful. Otherwise, verification MUST NOT be considered 632 successful for this ZONEMD RR. 634 5. IANA Considerations 636 5.1. ZONEMD RRtype 638 This document defines a new DNS RR type, ZONEMD, whose value 63 has 639 been allocated by IANA from the "Resource Record (RR) TYPEs" 640 subregistry of the "Domain Name System (DNS) Parameters" registry: 642 Type: ZONEMD 644 Value: 63 646 Meaning: Message Digest Over Zone Data 648 Reference: [this document] 650 5.2. ZONEMD Scheme 652 IANA is requested to create a new registry on the "Domain Name System 653 (DNS) Parameters" web page as follows: 655 Registry Name: ZONEMD Schemes 657 Registration Procedure: Specification Required 659 Reference: [this document] 660 +---------+---------------+----------+------------------+-----------+ 661 | Value | Description | Mnemonic | Implementation | Reference | 662 | | | | Requirement | | 663 +---------+---------------+----------+------------------+-----------+ 664 | 0 | Reserved | | | | 665 | 1 | Simple ZONEMD | SIMPLE | MUST | [this | 666 | | collation | | | document] | 667 | 2-239 | Unassigned | | | | 668 | 240-254 | Private Use | N/A | N/A | [this | 669 | | | | | document] | 670 | 255 | Reserved | | | | 671 +---------+---------------+----------+------------------+-----------+ 673 Table 1: ZONEMD Scheme Registry 675 5.3. ZONEMD Hash Algorithm 677 IANA is requested to create a new registry on the "Domain Name System 678 (DNS) Parameters" web page as follows: 680 Registry Name: ZONEMD Hash Algorithms 682 Registration Procedure: Specification Required 684 Reference: [this document] 686 +---------+-------------+----------+-------------------+------------+ 687 | Value | Description | Mnemonic | Implementation | Reference | 688 | | | | Requirement | | 689 +---------+-------------+----------+-------------------+------------+ 690 | 0 | Reserved | | | | 691 | 1 | SHA-384 | SHA384 | MUST | [this | 692 | | | | | document] | 693 | 2 | SHA-512 | SHA512 | SHOULD | [this | 694 | | | | | document] | 695 | 3-239 | Unassigned | | | | 696 | 240-254 | Private Use | N/A | N/A | [his | 697 | | | | | document] | 698 | 255 | Reserved | | | | 699 +---------+-------------+----------+-------------------+------------+ 701 Table 2: ZONEMD Hash Algorithm Registry 703 6. Security Considerations 704 6.1. Attacks Against the Zone Digest 706 The zone digest allows the recipient of a zone to verify its 707 integrity. In conjunction with DNSSEC, the recipient can 708 authenticate that it is as published by the zone originator. 710 An attacker, whose goal is to modify zone content before it is used 711 by the victim, may consider a number of different approaches. 713 The attacker might perform a downgrade attack to an unsigned zone. 714 This is why Section 4 talks about determining whether or not to 715 expect DNSSEC signatures for the zone in step 1. 717 The attacker might perform a downgrade attack by removing one or more 718 ZONEMD records. Such a removal is detectable only with DNSSEC 719 validation and is why Section 4 talks about checking denial-of- 720 existence proofs in step 2 and signature validation in step 3. 722 The attacker might alter the Scheme, Hash Algorithm, or Digest fields 723 of the ZONEMD record. Such modifications are detectable only with 724 DNSSEC validation. 726 6.2. DNSSESC Timing Considerations 728 As with all DNSSEC signatures, the ability to perform signature 729 validation of a ZONEMD record is limited in time. If the DS 730 record(s) or trust anchors for the zone to be verified are no longer 731 available, the recipient cannot validate the ZONEMD RRSet. This 732 could happen even if the ZONEMD signature is still current (not 733 expired), since the zone's DS record(s) may have been withdrawn 734 following a Key Signing Key (KSK) rollover. 736 For zones where it may be important to validate a ZONEMD RRSet 737 through its entire signature validity period, the zone operator 738 should ensure that KSK rollover timing takes this into consideration. 740 6.3. Attacks Utilizing ZONEMD Queries 742 Nothing in this specification prevents clients from making, and 743 servers from responding to, ZONEMD queries. Servers SHOULD NOT 744 calculate zone digests dynamically (for each query) as this can be 745 used as a CPU resource exhaustion attack. 747 ZONEMD responses could be used in a distributed denial-of-service 748 amplification attack. The ZONEMD RR is moderately sized, much like 749 the DS RR. A single ZONEMD RR contributes approximately 65 to 95 750 octets to a DNS response, for digest types defined herein. Other RR 751 types, such as DNSKEY, can result in larger amplification effects. 753 6.4. Resilience and Fragility 755 ZONEMD is used to detect incomplete or corrupted zone data prior to 756 its use, thereby increasing resilience by not using corrupt data, but 757 also introduces some denial-of-service fragility by making good data 758 in a zone unavailable if some other data is missing or corrupt. 759 Publishers and consumers of zones containing ZONEMD records should be 760 aware of these tradeoffs. While the intention is to secure the zone 761 data, misconfigurations or implementation bugs are generally 762 indistinguishable from intentional tampering, and could lead to 763 service failures when verification is performed automatically. 765 Zone publishers may want to deploy ZONEMD gradually, perhaps by 766 utilizing one of the private use hash algorithm code points listed in 767 Section 5.3. Similarly, recipients may want to initially configure 768 verification failures only as a warning, and later as an error after 769 gaining experience and confidence with the feature. 771 7. Performance Considerations 773 This section is provided to make zone publishers aware of the 774 performance requirements and implications of including ZONEMD RRs in 775 a zone. 777 7.1. SIMPLE SHA384 779 As mentioned previously, the SIMPLE scheme may be impractical for use 780 in zones that are either large or highly dynamic. Zone publishers 781 should carefully consider the use of ZONEMD in such zones, since it 782 might cause consumers of zone data (e.g., secondary name servers) to 783 expend resources on digest calculation. For such use cases, it is 784 recommended that ZONEMD only be used when digest calculation time is 785 significantly less than propagation times and update intervals. 787 The authors' implementation (Appendix B.1) includes an option to 788 record and report CPU usage of its operation. The software was used 789 to generate digests for more than 800 TLD zones available from 790 [CZDS]. The table below summarizes the results for the SIMPLE scheme 791 and SHA384 hash algorithm grouped by zone size. The Rate column is 792 the mean amount of time per RR to calculate the digest, running on 793 commodity hardware in early 2020. 795 +---------------------+----------------+ 796 | Zone Size (RRs) | Rate (msec/RR) | 797 +---------------------+----------------+ 798 | 10 - 99 | 0.00683 | 799 | 100 - 999 | 0.00551 | 800 | 1000 - 9999 | 0.00505 | 801 | 10000 - 99999 | 0.00602 | 802 | 100000 - 999999 | 0.00845 | 803 | 1000000 - 9999999 | 0.0108 | 804 | 10000000 - 99999999 | 0.0148 | 805 +---------------------+----------------+ 807 For example, based on the above table, it takes approximately 0.13 808 seconds to calculate a SIMPLE SHA384 digest for a zone with 22,000 809 RRs, and about 2.5 seconds for a zone with 300,000 RRs. 811 These benchmarks attempt to emulate a worst-case scenario and take 812 into account the time required to canonicalize the zone for 813 processing. Each of the 800+ zones were measured three times, and 814 then averaged, with a different random sorting of the input data 815 prior to each measurement. 817 8. Privacy Considerations 819 This specification has no impact on user privacy. 821 9. Acknowledgments 823 The authors wish to thank David Blacka, Scott Hollenbeck, and Rick 824 Wilhelm for providing feedback on early drafts of this document. 825 Additionally, they thank Joe Abley, Mark Andrews, Ralph Dolmans, 826 Donald Eastlake, Richard Gibson, Olafur Gudmundsson, Bob Harold, Paul 827 Hoffman, Evan Hunt, Shumon Huque, Tatuya Jinmei, Mike St. Johns, Burt 828 Kaliski, Shane Kerr, Matt Larson, Barry Leiba, John Levine, Ed Lewis, 829 Matt Pounsett, Mukund Sivaraman, Petr Spacek, Ondrej Sury, Willem 830 Toorop, Florian Weimer, Tim Wicinski, Wouter Wijngaards, Paul 831 Wouters, and other members of the DNS working group for their input. 833 10. Change Log 835 RFC Editor: Please remove this section before publication. 837 This section lists substantial changes to the document as it is being 838 worked on. 840 From -00 to -01: 842 o Removed requirement to sort by RR CLASS. 844 o Added Kumari and Hardaker as coauthors. 846 o Added Change Log section. 848 o Minor clarifications and grammatical edits. 850 From -01 to -02: 852 o Emphasize desire for data security over channel security. 854 o Expanded motivation into its own subsection. 856 o Removed discussion topic whether or not to include serial in 857 ZONEMD. 859 o Clarified that a zone's NS records always sort before the SOA 860 record. 862 o Clarified that all records in the zone must are digested, except 863 as specified in the exclusion rules. 865 o Added for discussion out-of-zone and occluded records. 867 o Clarified that update of ZONEMD signature must not cause a serial 868 number change. 870 o Added persons to acknowledgments. 872 From -02 to -03: 874 o Added recommendation to set ZONEMD TTL to SOA TTL. 876 o Clarified that digest input uses uncompressed names. 878 o Updated Implementations section. 880 o Changed intended status from Standards Track to Experimental and 881 added Scope of Experiment section. 883 o Updated Motivation, Introduction, and Design Overview sections in 884 response to working group discussion. 886 o Gave ZONEMD digest types their own status, separate from DS digest 887 types. Request IANA to create a registry. 889 o Added Reserved field for future work supporting dynamic updates. 891 o Be more rigorous about having just ONE ZONEMD record in the zone. 893 o Expanded use cases. 895 From -03 to -04: 897 o Added an appendix with example zones and digests. 899 o Clarified that only apex ZONEMD RRs shall be processed. 901 From -04 to -05: 903 o Made SHA384 the only supported ZONEMD digest type. 905 o Disassociated ZONEMD digest types from DS digest types. 907 o Updates to Introduction based on list feedback. 909 o Changed "zone file" to "zone" everywhere. 911 o Restored text about why ZONEMD has a Serial field. 913 o Clarified ordering of RRSets having same owner to be numerically 914 ascending. 916 o Clarified that all duplicate RRs (not just SOA) must be suppressed 917 in digest calculation. 919 o Clarified that the Reserved field must be set to zero and checked 920 for zero in verification. 922 o Clarified that occluded data must be included. 924 o Clarified procedure for verification, using temporary location for 925 received digest. 927 o Explained why Reserved field is 8-bits. 929 o IANA Considerations section now more specific. 931 o Added complex zone to examples. 933 o 935 From -05 to -06: 937 o RR type code 63 was assigned to ZONEMD by IANA. 939 From -06 to -07: 941 o Fixed mistakes in ZONEMD examples. 943 o Added private use Digest Type values 240-254. 945 o Clarified that Digest field must not be empty. 947 From -07 to draft-ietf-dnsop-dns-zone-digest-00: 949 o Adopted by dnsop. 951 o Clarified further that non-apex ZONEMD RRs have no meaning. 953 o Changed "provably [un]signed" to "provably [in]secure". 955 o Allow multiple ZONEMD RRs to support algorithm agility/rollovers. 957 o Describe verification when there are multiple ZONEMD RRs. 959 From -00 to -01: 961 o Simplified requirements around verifying multiple digests. Any 962 one match is sufficient. 964 o Updated implementation notes. 966 o Both implementations produce expected results on examples given in 967 this document. 969 From -01 to -02: 971 o Changed the name of the Reserved field to Parameter. 973 o Changed the name of Digest Type 1 from SHA384 to SHA384-STABLE. 975 o The meaning of the Parameter field now depends on Digest Type. 977 o No longer require Parameter field to be zero in verification. 979 o Updated a rule from earlier versions that said multiple ZONEMD RRs 980 were not allowed. 982 From -02 to -03: 984 o Changed the name of Digest Type 1 from SHA384-STABLE to 985 SHA384-SIMPLE. 987 o Changed document status from Experimental to Standards Track. 989 o Removed Scope of Experimentation section. 991 From -03 to -04: 993 o Addressing WGLC feedback. 995 o Changed from "Digest Type + Paramter" to "Scheme + Hash 996 Algorithm". This should make it more obvious how ZONEMD can be 997 expanded in the future with new schemes and hash algorithms, while 998 sacrificing some of the flexibility that the Parameter was 999 intended to provide. 1001 o Note: old RDATA fields: Serial, Digest Type, Parameter, Digest. 1003 o Note: new RDATA fields: Serial, Scheme, Hash Algorithm, Digest. 1005 o Add new IANA requirement for a Scheme registry. 1007 o Rearranged some sections and separated scheme-specific aspects 1008 from general aspects of digest calculation. 1010 o When discussing multiple ZONEMD RRs, allow for Scheme, as well as 1011 Hash Algorithm, transition. 1013 o Added Performance Considerations section with some benchmarks. 1015 o Further clarifications about non-apex ZONEMD RRs. 1017 o Clarified inclusion rule for duplicate RRs. 1019 o Removed or lowercased some inappropriately used RFC 2119 key 1020 words. 1022 o Clarified that all ZONEMD RRs, even for unsupported hash 1023 algorithms, must be zeroized during digest calculation. 1025 o Added Resilience and Fragility to security considerations. 1027 o Updated examples since changes in this version result in different 1028 hash values. 1030 From -04 to -05: 1032 o Clarifications about non-apex and multiple ZONEMD RRs. 1034 o Clarifications about benchmark results. 1036 o Don't compute ZONEMD on-the-fly. 1038 o Specification Required for updates to ZONEMD protocol registries. 1040 o Other rewording based on WGLC feedback. 1042 o Updated RFC numbers for some references. 1044 o Use documentation IP addresses instead of loopback. 1046 o Updated examples in the appendix. 1048 From -05 to -06: 1050 o Per WG suggestion, no longer include any apex ZONEMD record in 1051 digest calculation. 1053 o Updated examples in the appendix. 1055 o Clarified verification procedure by describing a loop over all 1056 ZONEMD RRs. 1058 From -06 to -07: 1060 o Added NIC Chile Labs implementation. 1062 From -07 to -08: 1064 o Update an author's affiliation. 1066 o Clarified why placeholder RRs are still important (for NSEC/ 1067 NSEC3). 1069 o Moved subsection ("Order of RRSets Having the Same Owner Name") 1070 with single sentence paragraph up into parent section. 1072 From -08 to -09: 1074 o Moved format, ordering, inclusion/exclusion into a sub section 1075 specific to the SIMPLE scheme. 1077 o Further clarified rules about multiple ZONEMD RRs (AD comments). 1079 o Reworded rules about processing of duplicate zone RRs (AD 1080 comments). 1082 o Removed sentence about optional zeroing of digest prior to 1083 calculation (AD comments). 1085 o Other minor changes (AD comments). 1087 From -09 to -10: 1089 o Add clarification and reference to on-disk modification / 1090 corruption of zone files. 1092 o Added concerns that timing of KSK rollovers could affect 1093 validation of ZONEMD record. 1095 o Addressed SECDIR review and accepted most proposed edits. 1097 o From SECDIR review, require minimum digest length of 12 octets. 1099 o From SECDIR review, add SHA512 has hash algorithm 2. 1101 o From SECDIR review, say that ZONEMD RRs MAY be ignored by local 1102 policy. 1104 o Moved Implementation Status to an appendix with the intention to 1105 retain it in RFC. 1107 o In registry tables, changed Status column to Implementation 1108 Requirement. 1110 From -10 to -11: 1112 o Fixed people's names in the acknowledgments section (blush) 1114 o Say "has not been modified between origination and retrieval." 1116 o Say that ZONEMD TTL doesn't matter during verification. 1118 o Further clarification that the SHA-384 and SHA-512 hashes are not 1119 truncated. Future algs might be truncated, but never below 96 1120 bits. 1122 From -11 to -12: 1124 o SECDIR review: make "recommended" all caps. 1126 o SECDIR review: tweak explanation of why ZONEMD RR has copy of SOA 1127 serial. 1129 o SECDIR review: be even more clear about apex ZONEMD RRs vs non- 1130 apex. 1132 o SECDIR review: Forgot to delete sentence about IANA policy for 1133 adding new hash algorithms. 1135 o SECDIR review: Spell out Key Signing Key first time. 1137 o SECDIR review: say "private use hash algorithm code points." 1139 o SECDIR review: Update estimates of ZONEMD RR size. 1141 11. References 1143 11.1. Normative References 1145 [RFC1034] Mockapetris, P., "Domain names - concepts and facilities", 1146 STD 13, RFC 1034, DOI 10.17487/RFC1034, November 1987, 1147 . 1149 [RFC1035] Mockapetris, P., "Domain names - implementation and 1150 specification", STD 13, RFC 1035, DOI 10.17487/RFC1035, 1151 November 1987, . 1153 [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate 1154 Requirement Levels", BCP 14, RFC 2119, 1155 DOI 10.17487/RFC2119, March 1997, 1156 . 1158 [RFC4034] Arends, R., Austein, R., Larson, M., Massey, D., and S. 1159 Rose, "Resource Records for the DNS Security Extensions", 1160 RFC 4034, DOI 10.17487/RFC4034, March 2005, 1161 . 1163 [RFC6234] Eastlake 3rd, D. and T. Hansen, "US Secure Hash Algorithms 1164 (SHA and SHA-based HMAC and HKDF)", RFC 6234, 1165 DOI 10.17487/RFC6234, May 2011, 1166 . 1168 [RFC8174] Leiba, B., "Ambiguity of Uppercase vs Lowercase in RFC 1169 2119 Key Words", BCP 14, RFC 8174, DOI 10.17487/RFC8174, 1170 May 2017, . 1172 11.2. Informative References 1174 [CZDS] Internet Corporation for Assigned Names and Numbers, 1175 "Centralized Zone Data Service", October 2018, 1176 . 1178 [disk-full-failure] 1179 DENIC, "Background of the Partial Failure of the Name 1180 Service for .de Domains", May 2010, 1181 . 1184 [DnsTools] 1185 NIC Chile Labs, "DNS tools for zone signature (file, 1186 pkcs11-hsm) and validation, and zone digest (ZONEMD)", 1187 April 2020, . 1189 [InterNIC] 1190 ICANN, "InterNIC FTP site", May 2018, 1191 . 1193 [ldns-zone-digest] 1194 Verisign, "Implementation of Message Digests for DNS Zones 1195 using the ldns library", July 2018, 1196 . 1198 [RFC1995] Ohta, M., "Incremental Zone Transfer in DNS", RFC 1995, 1199 DOI 10.17487/RFC1995, August 1996, 1200 . 1202 [RFC2065] Eastlake 3rd, D. and C. Kaufman, "Domain Name System 1203 Security Extensions", RFC 2065, DOI 10.17487/RFC2065, 1204 January 1997, . 1206 [RFC2136] Vixie, P., Ed., Thomson, S., Rekhter, Y., and J. Bound, 1207 "Dynamic Updates in the Domain Name System (DNS UPDATE)", 1208 RFC 2136, DOI 10.17487/RFC2136, April 1997, 1209 . 1211 [RFC2535] Eastlake 3rd, D., "Domain Name System Security 1212 Extensions", RFC 2535, DOI 10.17487/RFC2535, March 1999, 1213 . 1215 [RFC2845] Vixie, P., Gudmundsson, O., Eastlake 3rd, D., and B. 1216 Wellington, "Secret Key Transaction Authentication for DNS 1217 (TSIG)", RFC 2845, DOI 10.17487/RFC2845, May 2000, 1218 . 1220 [RFC2931] Eastlake 3rd, D., "DNS Request and Transaction Signatures 1221 ( SIG(0)s )", RFC 2931, DOI 10.17487/RFC2931, September 1222 2000, . 1224 [RFC4880] Callas, J., Donnerhacke, L., Finney, H., Shaw, D., and R. 1225 Thayer, "OpenPGP Message Format", RFC 4880, 1226 DOI 10.17487/RFC4880, November 2007, 1227 . 1229 [RFC5751] Ramsdell, B. and S. Turner, "Secure/Multipurpose Internet 1230 Mail Extensions (S/MIME) Version 3.2 Message 1231 Specification", RFC 5751, DOI 10.17487/RFC5751, January 1232 2010, . 1234 [RFC5936] Lewis, E. and A. Hoenes, Ed., "DNS Zone Transfer Protocol 1235 (AXFR)", RFC 5936, DOI 10.17487/RFC5936, June 2010, 1236 . 1238 [RFC7696] Housley, R., "Guidelines for Cryptographic Algorithm 1239 Agility and Selecting Mandatory-to-Implement Algorithms", 1240 BCP 201, RFC 7696, DOI 10.17487/RFC7696, November 2015, 1241 . 1243 [RFC7858] Hu, Z., Zhu, L., Heidemann, J., Mankin, A., Wessels, D., 1244 and P. Hoffman, "Specification for DNS over Transport 1245 Layer Security (TLS)", RFC 7858, DOI 10.17487/RFC7858, May 1246 2016, . 1248 [RFC8126] Cotton, M., Leiba, B., and T. Narten, "Guidelines for 1249 Writing an IANA Considerations Section in RFCs", BCP 26, 1250 RFC 8126, DOI 10.17487/RFC8126, June 2017, 1251 . 1253 [RFC8484] Hoffman, P. and P. McManus, "DNS Queries over HTTPS 1254 (DoH)", RFC 8484, DOI 10.17487/RFC8484, October 2018, 1255 . 1257 [RFC8499] Hoffman, P., Sullivan, A., and K. Fujiwara, "DNS 1258 Terminology", BCP 219, RFC 8499, DOI 10.17487/RFC8499, 1259 January 2019, . 1261 [RFC8806] Kumari, W. and P. Hoffman, "Running a Root Server Local to 1262 a Resolver", RFC 8806, DOI 10.17487/RFC8806, June 2020, 1263 . 1265 [RootServers] 1266 Root Server Operators, "Root Server Technical Operations", 1267 July 2018, . 1269 [RPZ] Vixie, P. and V. Schryver, "DNS Response Policy Zones 1270 (RPZ)", draft-vixie-dnsop-dns-rpz-00 (work in progress), 1271 June 2018, . 1274 [ZoneDigestHackathon] 1275 Kerr, S., "Prototype implementation of ZONEMD for the IETF 1276 102 hackathon in Python", July 2018, 1277 . 1279 Appendix A. Example Zones With Digests 1281 This appendix contains example zones with accurate ZONEMD records. 1282 These can be used to verify an implementation of the zone digest 1283 protocol. 1285 A.1. Simple EXAMPLE Zone 1287 Here, the EXAMPLE zone contains an SOA record, NS and glue records, 1288 and a ZONEMD record. 1290 example. 86400 IN SOA ns1 admin 2018031900 ( 1291 1800 900 604800 86400 ) 1292 86400 IN NS ns1 1293 86400 IN NS ns2 1294 86400 IN ZONEMD 2018031900 1 1 ( 1295 c68090d90a7aed71 1296 6bc459f9340e3d7c 1297 1370d4d24b7e2fc3 1298 a1ddc0b9a87153b9 1299 a9713b3c9ae5cc27 1300 777f98b8e730044c ) 1301 ns1 3600 IN A 203.0.113.63 1302 ns2 3600 IN AAAA 2001:db8::63 1304 A.2. Complex EXAMPLE Zone 1306 Here, the EXAMPLE zone contains duplicate RRs, and an occluded RR, 1307 and one out-of-zone RR. 1309 example. 86400 IN SOA ns1 admin 2018031900 ( 1310 1800 900 604800 86400 ) 1311 86400 IN NS ns1 1312 86400 IN NS ns2 1313 86400 IN ZONEMD 2018031900 1 1 ( 1314 31cefb03814f5062 1315 ad12fa951ba0ef5f 1316 8da6ae354a415767 1317 246f7dc932ceb1e7 1318 42a2108f529db6a3 1319 3a11c01493de358d ) 1320 ns1 3600 IN A 203.0.113.63 1321 ns2 3600 IN AAAA 2001:db8::63 1322 occluded.sub 7200 IN TXT "I'm occluded but must be digested" 1323 sub 7200 IN NS ns1 1324 duplicate 300 IN TXT "I must be digested just once" 1325 duplicate 300 IN TXT "I must be digested just once" 1326 foo.test. 555 IN TXT "out-of-zone data must be excluded" 1327 non-apex 900 IN ZONEMD 2018031900 1 1 ( 1328 616c6c6f77656420 1329 6275742069676e6f 1330 7265642e20616c6c 1331 6f77656420627574 1332 2069676e6f726564 1333 2e20616c6c6f7765 ) 1335 A.3. EXAMPLE Zone with multiple digests 1337 Here, the EXAMPLE zone contains multiple ZONEMD records. It has both 1338 SHA384 and SHA512 digests using the SIMPLE scheme. It also includes 1339 ZONEMD records with Scheme and Hash Algorithm values in the private 1340 range (240-254). These additional private-range digests are not 1341 verifiable. 1343 example. 86400 IN SOA ns1 admin 2018031900 ( 1344 1800 900 604800 86400 ) 1345 example. 86400 IN NS ns1.example. 1346 example. 86400 IN NS ns2.example. 1347 example. 86400 IN ZONEMD 2018031900 1 1 ( 1348 62e6cf51b02e54b9 1349 b5f967d547ce4313 1350 6792901f9f88e637 1351 493daaf401c92c27 1352 9dd10f0edb1c56f8 1353 080211f8480ee306 ) 1354 example. 86400 IN ZONEMD 2018031900 1 2 ( 1355 08cfa1115c7b948c 1356 4163a901270395ea 1357 226a930cd2cbcf2f 1358 a9a5e6eb85f37c8a 1359 4e114d884e66f176 1360 eab121cb02db7d65 1361 2e0cc4827e7a3204 1362 f166b47e5613fd27 ) 1363 example. 86400 IN ZONEMD 2018031900 1 240 ( 1364 e2d523f654b9422a 1365 96c5a8f44607bbee ) 1366 example. 86400 IN ZONEMD 2018031900 241 1 ( 1367 e1846540e33a9e41 1368 89792d18d5d131f6 1369 05fc283e ) 1370 ns1.example. 3600 IN A 203.0.113.63 1371 ns2.example. 86400 IN TXT "This example has multiple digests" 1372 ns2.example. 3600 IN AAAA 2001:db8::63 1374 A.4. The URI.ARPA Zone 1376 The URI.ARPA zone retrieved 2018-10-21. Note this sample zone has 1377 (expired) signatures, but no signature for the ZONEMD RR. 1379 ; <<>> DiG 9.9.4 <<>> @lax.xfr.dns.icann.org uri.arpa axfr 1380 ; (2 servers found) 1381 ;; global options: +cmd 1382 uri.arpa. 3600 IN SOA sns.dns.icann.org. ( 1383 noc.dns.icann.org. 2018100702 10800 3600 1209600 3600 ) 1384 uri.arpa. 3600 IN RRSIG NSEC 8 2 3600 ( 1385 20181028142623 20181007205525 47155 uri.arpa. 1386 eEC4w/oXLR1Epwgv4MBiDtSBsXhqrJVvJWUpbX8XpetAvD35bxwNCUTi 1387 /pAJVUXefegWeiriD2rkTgCBCMmn7YQIm3gdR+HjY/+o3BXNQnz97f+e 1388 HAE9EDDzoNVfL1PyV/2fde9tDeUuAGVVwmD399NGq9jWYMRpyri2kysr q/g= ) 1389 uri.arpa. 86400 IN RRSIG NS 8 2 86400 ( 1390 20181028172020 20181007175821 47155 uri.arpa. 1392 ATyV2A2A8ZoggC+68u4GuP5MOUuR+2rr3eWOkEU55zAHld/7FiBxl4ln 1393 4byJYy7NudUwlMOEXajqFZE7DVl8PpcvrP3HeeGaVzKqaWj+aus0jbKF 1394 Bsvs2b1qDZemBfkz/IfAhUTJKnto0vSUicJKfItu0GjyYNJCz2CqEuGD Wxc= ) 1395 uri.arpa. 600 IN RRSIG MX 8 2 600 ( 1396 20181028170556 20181007175821 47155 uri.arpa. 1397 e7/r3KXDohX1lyVavetFFObp8fB8aXT76HnN9KCQDxSnSghNM83UQV0t 1398 lTtD8JVeN1mCvcNFZpagwIgB7XhTtm6Beur/m5ES+4uSnVeS6Q66HBZK 1399 A3mR95IpevuVIZvvJ+GcCAQpBo6KRODYvJ/c/ZG6sfYWkZ7qg/Em5/+3 4UI= ) 1400 uri.arpa. 3600 IN RRSIG DNSKEY 8 2 3600 ( 1401 20181028152832 20181007175821 15796 uri.arpa. 1402 nzpbnh0OqsgBBP8St28pLvPEQ3wZAUdEBuUwil+rtjjWlYYiqjPxZ286 1403 XF4Rq1usfV5x71jZz5IqswOaQgia91ylodFpLuXD6FTGs2nXGhNKkg1V 1404 chHgtwj70mXU72GefVgo8TxrFYzxuEFP5ZTP92t97FVWVVyyFd86sbbR 1405 6DZj3uA2wEvqBVLECgJLrMQ9Yy7MueJl3UA4h4E6zO2JY9Yp0W9woq0B 1406 dqkkwYTwzogyYffPmGAJG91RJ2h6cHtFjEZe2MnaY2glqniZ0WT9vXXd 1407 uFPm0KD9U77Ac+ZtctAF9tsZwSdAoL365E2L1usZbA+K0BnPPqGFJRJk 1408 5R0A1w== ) 1409 uri.arpa. 3600 IN RRSIG DNSKEY 8 2 3600 ( 1410 20181028152832 20181007175821 55480 uri.arpa. 1411 lWtQV/5szQjkXmbcD47/+rOW8kJPksRFHlzxxmzt906+DBYyfrH6uq5X 1412 nHvrUlQO6M12uhqDeL+bDFVgqSpNy+42/OaZvaK3J8EzPZVBHPJykKMV 1413 63T83aAiJrAyHzOaEdmzLCpalqcEE2ImzlLHSafManRfJL8Yuv+JDZFj 1414 2WDWfEcUuwkmIZWX11zxp+DxwzyUlRl7x4+ok5iKZWIg5UnBAf6B8T75 1415 WnXzlhCw3F2pXI0a5LYg71L3Tp/xhjN6Yy9jGlIRf5BjB59X2zra3a2R 1416 PkI09SSnuEwHyF1mDaV5BmQrLGRnCjvwXA7ho2m+vv4SP5dUdXf+GTeA 1417 1HeBfw== ) 1418 uri.arpa. 3600 IN RRSIG SOA 8 2 3600 ( 1419 20181029114753 20181008222815 47155 uri.arpa. 1420 qn8yBNoHDjGdT79U2Wu9IIahoS0YPOgYP8lG+qwPcrZ1BwGiHywuoUa2 1421 Mx6BWZlg+HDyaxj2iOmox+IIqoUHhXUbO7IUkJFlgrOKCgAR2twDHrXu 1422 9BUQHy9SoV16wYm3kBTEPyxW5FFm8vcdnKAF7sxSY8BbaYNpRIEjDx4A JUc= ) 1423 uri.arpa. 3600 IN NSEC ftp.uri.arpa. NS SOA ( 1424 MX RRSIG NSEC DNSKEY ) 1425 uri.arpa. 86400 IN NS a.iana-servers.net. 1426 uri.arpa. 86400 IN NS b.iana-servers.net. 1427 uri.arpa. 86400 IN NS c.iana-servers.net. 1428 uri.arpa. 86400 IN NS ns2.lacnic.net. 1429 uri.arpa. 86400 IN NS sec3.apnic.net. 1430 uri.arpa. 600 IN MX 10 pechora.icann.org. 1431 uri.arpa. 3600 IN DNSKEY 256 3 8 ( 1432 AwEAAcBi7tSart2J599zbYWspMNGN70IBWb4ziqyQYH9MTB/VCz6WyUK 1433 uXunwiJJbbQ3bcLqTLWEw134B6cTMHrZpjTAb5WAwg4XcWUu8mdcPTiL 1434 Bl6qVRlRD0WiFCTzuYUfkwsh1Rbr7rvrxSQhF5rh71zSpwV5jjjp65Wx 1435 SdJjlH0B ) 1436 uri.arpa. 3600 IN DNSKEY 257 3 8 ( 1437 AwEAAbNVv6ulgRdO31MtAehz7j3ALRjwZglWesnzvllQl/+hBRZr9QoY 1438 cO2I+DkO4Q1NKxox4DUIxj8SxPO3GwDuOFR9q2/CFi2O0mZjafbdYtWc 1439 3zSdBbi3q0cwCIx7GuG9eqlL+pg7mdk9dgdNZfHwB0LnqTD8ebLPsrO/ 1440 Id7kBaiqYOfMlZnh2fp+2h6OOJZHtY0DK1UlssyB5PKsE0tVzo5s6zo9 1441 iXKe5u+8WTMaGDY49vG80JPAKE7ezMiH/NZcUMiE0PRZ8D3foq2dYuS5 1442 ym+vA83Z7v8A+Rwh4UGnjxKB8zmr803V0ASAmHz/gwH5Vb0nH+LObwFt 1443 l3wpbp+Wpm8= ) 1444 uri.arpa. 3600 IN DNSKEY 257 3 8 ( 1445 AwEAAbwnFTakCvaUKsXji4mgmxZUJi1IygbnGahbkmFEa0L16J+TchKR 1446 wcgzVfsxUGa2MmeA4hgkAooC3uy+tTmoMsgy8uq/JAj24DjiHzd46LfD 1447 FK/qMidVqFpYSHeq2Vv5ojkuIsx4oe4KsafGWYNOczKZgH5loGjN2aJG 1448 mrIm++XCphOskgCsQYl65MIzuXffzJyxlAuts+ecAIiVeqRaqQfr8LRU 1449 7wIsLxinXirprtQrbor+EtvlHp9qXE6ARTZDzf4jvsNpKvLFZtmxzFf3 1450 e/UJz5eHjpwDSiZL7xE8aE1o1nGfPtJx9ZnB3bapltaJ5wY+5XOCKgY0 1451 xmJVvNQlwdE= ) 1452 ftp.uri.arpa. 3600 IN RRSIG NSEC 8 3 3600 ( 1453 20181028080856 20181007175821 47155 uri.arpa. 1454 HClGAqPxzkYkAT7Q/QNtQeB6YrkP6EPOef+9Qo5/2zngwAewXEAQiyF9 1455 jD1USJiroM11QqBS3v3aIdW/LXORs4Ez3hLcKNO1cKHsOuWAqzmE+BPP 1456 Arfh8N95jqh/q6vpaB9UtMkQ53tM2fYU1GszOLN0knxbHgDHAh2axMGH lqM= ) 1457 ftp.uri.arpa. 604800 IN RRSIG NAPTR 8 3 604800 ( 1458 20181028103644 20181007205525 47155 uri.arpa. 1459 WoLi+vZzkxaoLr2IGZnwkRvcDf6KxiWQd1WZP/U+AWnV+7MiqsWPZaf0 1460 9toRErerGoFOiOASNxZjBGJrRgjmavOM9U+LZSconP9zrNFd4dIu6kp5 1461 YxlQJ0uHOvx1ZHFCj6lAt1ACUIw04ZhMydTmi27c8MzEOMepvn7iH7r7 k7k= ) 1462 ftp.uri.arpa. 3600 IN NSEC http.uri.arpa. NAPTR ( 1463 RRSIG NSEC ) 1464 ftp.uri.arpa. 604800 IN NAPTR 0 0 "" "" ( 1465 "!^ftp://([^:/?#]*).*$!\\1!i" . ) 1466 http.uri.arpa. 3600 IN RRSIG NSEC 8 3 3600 ( 1467 20181029010647 20181007175821 47155 uri.arpa. 1468 U03NntQ73LHWpfLmUK8nMsqkwVsOGW2KdsyuHYAjqQSZvKbtmbv7HBmE 1469 H1+Ii3Z+wtfdMZBy5aC/6sHdx69BfZJs16xumycMlAy6325DKTQbIMN+ 1470 ift9GrKBC7cgCd2msF/uzSrYxxg4MJQzBPvlkwXnY3b7eJSlIXisBIn7 3b8= ) 1471 http.uri.arpa. 604800 IN RRSIG NAPTR 8 3 604800 ( 1472 20181029011815 20181007205525 47155 uri.arpa. 1473 T7mRrdag+WSmG+n22mtBSQ/0Y3v+rdDnfQV90LN5Fq32N5K2iYFajF7F 1474 Tp56oOznytfcL4fHrqOE0wRc9NWOCCUec9C7Wa1gJQcllEvgoAM+L6f0 1475 RsEjWq6+9jvlLKMXQv0xQuMX17338uoD/xiAFQSnDbiQKxwWMqVAimv5 7Zs= ) 1476 http.uri.arpa. 3600 IN NSEC mailto.uri.arpa. NAPTR ( 1477 RRSIG NSEC ) 1478 http.uri.arpa. 604800 IN NAPTR 0 0 "" "" ( 1479 "!^http://([^:/?#]*).*$!\\1!i" . ) 1480 mailto.uri.arpa. 3600 IN RRSIG NSEC 8 3 3600 ( 1481 20181028110727 20181007175821 47155 uri.arpa. 1482 GvxzVL85rEukwGqtuLxek9ipwjBMfTOFIEyJ7afC8HxVMs6mfFa/nEM/ 1483 IdFvvFg+lcYoJSQYuSAVYFl3xPbgrxVSLK125QutCFMdC/YjuZEnq5cl 1484 fQciMRD7R3+znZfm8d8u/snLV9w4D+lTBZrJJUBe1Efc8vum5vvV7819 ZoY= ) 1485 mailto.uri.arpa. 604800 IN RRSIG NAPTR 8 3 604800 ( 1486 20181028141825 20181007205525 47155 uri.arpa. 1487 MaADUgc3fc5v++M0YmqjGk3jBdfIA5RuP62hUSlPsFZO4k37erjIGCfF 1488 j+g84yc+QgbSde0PQHszl9fE/+SU5ZXiS9YdcbzSZxp2erFpZOTchrpg 1489 916T4vx6i59scodjb0l6bDyZ+mtIPrc1w6b4hUyOUTsDQoAJYxdfEuMg Vy4= ) 1490 mailto.uri.arpa. 3600 IN NSEC urn.uri.arpa. NAPTR ( 1491 RRSIG NSEC ) 1492 mailto.uri.arpa. 604800 IN NAPTR 0 0 "" "" ( 1493 "!^mailto:(.*)@(.*)$!\\2!i" . ) 1494 urn.uri.arpa. 3600 IN RRSIG NSEC 8 3 3600 ( 1495 20181028123243 20181007175821 47155 uri.arpa. 1496 Hgsw4Deops1O8uWyELGe6hpR/OEqCnTHvahlwiQkHhO5CSEQrbhmFAWe 1497 UOkmGAdTEYrSz+skLRQuITRMwzyFf4oUkZihGyhZyzHbcxWfuDc/Pd/9 1498 DSl56gdeBwy1evn5wBTms8yWQVkNtphbJH395gRqZuaJs3LD/qTyJ5Dp LvA= ) 1499 urn.uri.arpa. 604800 IN RRSIG NAPTR 8 3 604800 ( 1500 20181029071816 20181007205525 47155 uri.arpa. 1501 ALIZD0vBqAQQt40GQ0Efaj8OCyE9xSRJRdyvyn/H/wZVXFRFKrQYrLAS 1502 D/K7q6CMTOxTRCu2J8yes63WJiaJEdnh+dscXzZkmOg4n5PsgZbkvUSW 1503 BiGtxvz5jNncM0xVbkjbtByrvJQAO1cU1mnlDKe1FmVB1uLpVdA9Ib4J hMU= ) 1504 urn.uri.arpa. 3600 IN NSEC uri.arpa. NAPTR RRSIG ( 1505 NSEC ) 1506 urn.uri.arpa. 604800 IN NAPTR 0 0 "" "" ( 1507 "/urn:([^:]+)/\\1/i" . ) 1508 uri.arpa. 3600 IN SOA sns.dns.icann.org. ( 1509 noc.dns.icann.org. 2018100702 10800 3600 1209600 3600 ) 1510 ;; Query time: 66 msec 1511 ;; SERVER: 192.0.32.132#53(192.0.32.132) 1512 ;; WHEN: Sun Oct 21 20:39:28 UTC 2018 1513 ;; XFR size: 34 records (messages 1, bytes 3941) 1514 uri.arpa. 3600 IN ZONEMD 2018100702 1 1 ( 1515 1291b78ddf7669b1a39d014d87626b709b55774c5d7d58fa 1516 dc556439889a10eaf6f11d615900a4f996bd46279514e473 ) 1518 A.5. The ROOT-SERVERS.NET Zone 1520 The ROOT-SERVERS.NET zone retrieved 2018-10-21. 1522 root-servers.net. 3600000 IN SOA a.root-servers.net. ( 1523 nstld.verisign-grs.com. 2018091100 14400 7200 1209600 3600000 ) 1524 root-servers.net. 3600000 IN NS a.root-servers.net. 1525 root-servers.net. 3600000 IN NS b.root-servers.net. 1526 root-servers.net. 3600000 IN NS c.root-servers.net. 1527 root-servers.net. 3600000 IN NS d.root-servers.net. 1528 root-servers.net. 3600000 IN NS e.root-servers.net. 1529 root-servers.net. 3600000 IN NS f.root-servers.net. 1530 root-servers.net. 3600000 IN NS g.root-servers.net. 1531 root-servers.net. 3600000 IN NS h.root-servers.net. 1532 root-servers.net. 3600000 IN NS i.root-servers.net. 1533 root-servers.net. 3600000 IN NS j.root-servers.net. 1534 root-servers.net. 3600000 IN NS k.root-servers.net. 1535 root-servers.net. 3600000 IN NS l.root-servers.net. 1536 root-servers.net. 3600000 IN NS m.root-servers.net. 1537 a.root-servers.net. 3600000 IN AAAA 2001:503:ba3e::2:30 1538 a.root-servers.net. 3600000 IN A 198.41.0.4 1539 b.root-servers.net. 3600000 IN MX 20 mail.isi.edu. 1540 b.root-servers.net. 3600000 IN AAAA 2001:500:200::b 1541 b.root-servers.net. 3600000 IN A 199.9.14.201 1542 c.root-servers.net. 3600000 IN AAAA 2001:500:2::c 1543 c.root-servers.net. 3600000 IN A 192.33.4.12 1544 d.root-servers.net. 3600000 IN AAAA 2001:500:2d::d 1545 d.root-servers.net. 3600000 IN A 199.7.91.13 1546 e.root-servers.net. 3600000 IN AAAA 2001:500:a8::e 1547 e.root-servers.net. 3600000 IN A 192.203.230.10 1548 f.root-servers.net. 3600000 IN AAAA 2001:500:2f::f 1549 f.root-servers.net. 3600000 IN A 192.5.5.241 1550 g.root-servers.net. 3600000 IN AAAA 2001:500:12::d0d 1551 g.root-servers.net. 3600000 IN A 192.112.36.4 1552 h.root-servers.net. 3600000 IN AAAA 2001:500:1::53 1553 h.root-servers.net. 3600000 IN A 198.97.190.53 1554 i.root-servers.net. 3600000 IN MX 10 mx.i.root-servers.org. 1555 i.root-servers.net. 3600000 IN AAAA 2001:7fe::53 1556 i.root-servers.net. 3600000 IN A 192.36.148.17 1557 j.root-servers.net. 3600000 IN AAAA 2001:503:c27::2:30 1558 j.root-servers.net. 3600000 IN A 192.58.128.30 1559 k.root-servers.net. 3600000 IN AAAA 2001:7fd::1 1560 k.root-servers.net. 3600000 IN A 193.0.14.129 1561 l.root-servers.net. 3600000 IN AAAA 2001:500:9f::42 1562 l.root-servers.net. 3600000 IN A 199.7.83.42 1563 m.root-servers.net. 3600000 IN AAAA 2001:dc3::35 1564 m.root-servers.net. 3600000 IN A 202.12.27.33 1565 root-servers.net. 3600000 IN SOA a.root-servers.net. ( 1566 nstld.verisign-grs.com. 2018091100 14400 7200 1209600 3600000 ) 1567 root-servers.net. 3600000 IN ZONEMD 2018091100 1 1 ( 1568 f1ca0ccd91bd5573d9f431c00ee0101b2545c97602be0a97 1569 8a3b11dbfc1c776d5b3e86ae3d973d6b5349ba7f04340f79 ) 1571 Appendix B. Implementation Status 1573 RFC Editor: Please retain this section upon publication. 1575 This section records the status of known implementations of the 1576 protocol defined by this specification at the time of posting of this 1577 Internet-Draft, and is based on a proposal described in RFC 7942. 1578 The description of implementations in this section is intended to 1579 assist the IETF in its decision processes in progressing drafts to 1580 RFCs. Please note that the listing of any individual implementation 1581 here does not imply endorsement by the IETF. Furthermore, no effort 1582 has been spent to verify the information presented here that was 1583 supplied by IETF contributors. This is not intended as, and must not 1584 be construed to be, a catalog of available implementations or their 1585 features. Readers are advised to note that other implementations may 1586 exist. 1588 B.1. Authors' Implementation 1590 The authors have an open source implementation in C, using the ldns 1591 library [ldns-zone-digest]. This implementation is able to perform 1592 the following functions: 1594 o Read an input zone and output a zone with the ZONEMD placeholder. 1596 o Compute zone digest over signed zone and update the ZONEMD record. 1598 o Re-compute DNSSEC signature over the ZONEMD record. 1600 o Verify the zone digest from an input zone. 1602 This implementation does not: 1604 o Perform DNSSEC validation of the ZONEMD record during 1605 verification. 1607 B.2. Shane Kerr's Implementation 1609 Shane Kerr wrote an implementation of this specification during the 1610 IETF 102 hackathon [ZoneDigestHackathon]. This implementation is in 1611 Python and is able to perform the following functions: 1613 o Read an input zone and output a zone with ZONEMD record. 1615 o Verify the zone digest from an input zone. 1617 o Output the ZONEMD record in its defined presentation format. 1619 This implementation does not: 1621 o Re-compute DNSSEC signature over the ZONEMD record. 1623 o Perform DNSSEC validation of the ZONEMD record. 1625 B.3. NIC Chile Labs Implementation 1627 NIC Chile Labs wrote an implementation of this specification as part 1628 of "dns-tools" suite [DnsTools], which besides digesting, can also 1629 sign and verify zones. This implementation is in Go and is able to 1630 perform the following functions: 1632 o Compute zone digest over signed zone and update the ZONEMD record. 1634 o Verify the zone digest from an input zone. 1636 o Perform DNSSEC validation of the ZONEMD record during 1637 verification. 1639 o Re-compute DNSSEC signature over the ZONEMD record. 1641 Authors' Addresses 1643 Duane Wessels 1644 Verisign 1645 12061 Bluemont Way 1646 Reston, VA 20190 1648 Phone: +1 703 948-3200 1649 Email: dwessels@verisign.com 1650 URI: https://verisign.com 1652 Piet Barber 1653 Verisign 1654 12061 Bluemont Way 1655 Reston, VA 20190 1657 Phone: +1 703 948-3200 1658 Email: pbarber@verisign.com 1659 URI: https://verisign.com 1660 Matt Weinberg 1661 Amazon 1663 Email: matweinb@amazon.com 1664 URI: https://amazon.com 1666 Warren Kumari 1667 Google 1668 1600 Amphitheatre Parkway 1669 Mountain View, CA 94043 1671 Email: warren@kumari.net 1673 Wes Hardaker 1674 USC/ISI 1675 P.O. Box 382 1676 Davis, CA 95617 1678 Email: ietf@hardakers.net