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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: March 29, 2021 M. Weinberg 6 Amazon 7 W. Kumari 8 Google 9 W. Hardaker 10 USC/ISI 11 September 25, 2020 13 Message Digest for DNS Zones 14 draft-ietf-dnsop-dns-zone-digest-11 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 March 29, 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 . . . . . . . . . . . . . . . . . . . 16 104 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 . . . . . . . . . . . . . . . . . . . . . . . . . 24 114 11.1. Normative References . . . . . . . . . . . . . . . . . . 24 115 11.2. Informative References . . . . . . . . . . . . . . . . . 25 116 Appendix A. Example Zones With Digests . . . . . . . . . . . . . 27 117 A.1. Simple EXAMPLE Zone . . . . . . . . . . . . . . . . . . . 27 118 A.2. Complex EXAMPLE Zone . . . . . . . . . . . . . . . . . . 28 119 A.3. EXAMPLE Zone with multiple digests . . . . . . . . . . . 29 120 A.4. The URI.ARPA Zone . . . . . . . . . . . . . . . . . . . . 29 121 A.5. The ROOT-SERVERS.NET Zone . . . . . . . . . . . . . . . . 32 122 Appendix B. Implementation Status . . . . . . . . . . . . . . . 34 123 B.1. Authors' Implementation . . . . . . . . . . . . . . . . . 34 124 B.2. Shane Kerr's Implementation . . . . . . . . . . . . . . . 34 125 B.3. NIC Chile Labs Implementation . . . . . . . . . . . . . . 35 126 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 35 128 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 in order to make DNS response messages of type 382 ZONEMD meaningful. Without the serial number, a stand-alone ZONEMD 383 digest has no association to any particular instance of a zone. 385 2.2.2. The Scheme Field 387 The Scheme field is an 8-bit unsigned integer that identifies the 388 methods by which data is collated and presented as input to the 389 hashing function. 391 Herein, SIMPLE, with value 1, is the only standardized Scheme defined 392 for ZONEMD records and it MUST be implemented. The Scheme registry 393 is further described in Section 5. 395 Scheme values 240-254 are allocated for Private Use. 397 2.2.3. The Hash Algorithm Field 399 The Hash Algorithm field is an 8-bit unsigned integer that identifies 400 the cryptographic hash algorithm used to construct the digest. 402 Herein, SHA384 [RFC6234], with value 1, is the only standardized Hash 403 Algorithm defined for ZONEMD records that MUST be implemented. When 404 SHA384 is used, the size of the Digest field is 48 octets. The 405 result of the SHA384 digest algorithm MUST NOT be truncated, and the 406 entire 48 octet digest is published in the ZONEMD record. 408 SHA512 [RFC6234], with Hash Algorithm value 2, is also defined for 409 ZONEMD records, and SHOULD be implemented. When SHA512 is used, the 410 size of the Digest field is 64 octets. The result of the SHA512 411 digest algorithm MUST NOT be truncated, and the entire 64 octet 412 digest is published in the ZONEMD record. 414 Hash Algorithm values 240-254 are allocated for Private Use. 416 The Hash Algorithm registry is further described in Section 5. 418 2.2.4. The Digest Field 420 The Digest field is a variable-length sequence of octets containing 421 the output of the hash algorithm. The length of the Digest field is 422 determined by deducting the fixed size of the Serial, Scheme, and 423 Hash Algorithm fields from the RDATA size in the ZONEMD RR header. 425 The Digest field MUST NOT be shorter than 12 octets. Digests for the 426 SHA384 and SHA512 hash algorithms specified herein are never 427 truncated. Digests for future hash algorithms MAY be truncated, but 428 MUST NOT be truncated to a length that results in less than 96-bits 429 (12 octets) of equivalent strength. 431 Section 3 describes how to calculate the digest for a zone. 432 Section 4 describes how to use the digest to verify the contents of a 433 zone. 435 2.3. ZONEMD Presentation Format 437 The presentation format of the RDATA portion is as follows: 439 The Serial field is represented as an unsigned decimal integer. 441 The Scheme field is represented as an unsigned decimal integer. 443 The Hash Algorithm field is represented as an unsigned decimal 444 integer. 446 The Digest is represented as a sequence of case-insensitive 447 hexadecimal digits. Whitespace is allowed within the hexadecimal 448 text. 450 2.4. ZONEMD Example 452 The following example shows a ZONEMD RR in presentation format: 454 example.com. 86400 IN ZONEMD 2018031500 1 1 ( 455 FEBE3D4CE2EC2FFA4BA99D46CD69D6D29711E55217057BEE 456 7EB1A7B641A47BA7FED2DD5B97AE499FAFA4F22C6BD647DE ) 458 3. Calculating the Digest 460 3.1. Add ZONEMD Placeholder 462 In preparation for calculating the zone digest, any existing ZONEMD 463 records (and covering RRSIGs) at the zone apex are first deleted. 465 Prior to calculation of the digest, and prior to signing with DNSSEC, 466 one or more placeholder ZONEMD records are added to the zone apex. 467 This ensures that denial-of-existence (NSEC, NSEC3) records are 468 created correctly if the zone is signed with DNSSEC. If placeholders 469 were not added prior to signing, the later addition of ZONEMD records 470 would also require updating the Type Bit Maps field of any apex NSEC/ 471 NSEC3 RRs, which then invalidates the calculated digest value. 473 When multiple ZONEMD RRs are published in the zone, e.g., during an 474 algorithm rollover, each MUST specify a unique Scheme and Hash 475 Algorithm tuple. 477 It is RECOMMENDED that the TTL of the ZONEMD record match the TTL of 478 the SOA. However, the TTL of the ZONEMD record may be safely ignored 479 during verification in all cases. 481 In the placeholder record, the Serial field is set to the current SOA 482 Serial. The Scheme field is set to the value for the chosen 483 collation scheme. The Hash Algorithm field is set to the value for 484 the chosen hash algorithm. Since ZONEMD records are excluded from 485 digest calculation, the value of the Digest field does not matter at 486 this point in the process. 488 3.2. Optionally Sign the Zone 490 Following addition of placeholder records, the zone may be signed 491 with DNSSEC. When the digest calculation is complete, and the ZONEMD 492 record is updated, the signature(s) for the ZONEMD RRSet MUST be 493 recalculated and updated as well. Therefore, the signer is not 494 required to calculate a signature over the placeholder record at this 495 step in the process, but it is harmless to do so. 497 3.3. Scheme-Specific Processing 499 Herein, only the SIMPLE collation scheme is defined. Additional 500 schemes may be defined in future updates to this document. 502 3.3.1. The SIMPLE Scheme 504 For the SIMPLE scheme, the digest is calculated over the zone as a 505 whole. This means that a change to a single RR in the zone requires 506 iterating over all RRs in the zone to recalculate the digest. SIMPLE 507 is a good choice for zones that are small and/or stable, but probably 508 not good for zones that are large and/or dynamic. 510 Calculation of a zone digest REQUIRES RRs to be processed in a 511 consistent format and ordering. This specification uses DNSSEC's 512 canonical on-the-wire RR format (without name compression) and 513 ordering as specified in Sections 6.1, 6.2, and 6.3 of [RFC4034] with 514 the additional provision that RRSets having the same owner name MUST 515 be numerically ordered, in ascending order, by their numeric RR TYPE. 517 3.3.1.1. SIMPLE Scheme Inclusion/Exclusion Rules 519 When iterating over records in the zone, the following inclusion/ 520 exclusion rules apply: 522 o All records in the zone, including glue records, MUST be included. 524 o Occluded data ([RFC5936] Section 3.5) MUST be included. 526 o If there are duplicate RRs with equal owner, class, type, and 527 RDATA, only one instance is included ([RFC4034] Section 6.3), and 528 the duplicates MUST be omitted. 530 o The placeholder ZONEMD RR(s) MUST NOT be included. 532 o If the zone is signed, DNSSEC RRs MUST be included, except: 534 o The RRSIG covering ZONEMD MUST NOT be included because the RRSIG 535 will be updated after all digests have been calculated. 537 3.3.1.2. SIMPLE Scheme Digest Calculation 539 A zone digest using the SIMPLE scheme is calculated by concatenating 540 all RRs in the zone, in the format and order described in 541 Section 3.3.1 subject to the inclusion/exclusion rules described in 542 Section 3.3.1.1, and then applying the chosen hash algorithm: 544 digest = hash( RR(1) | RR(2) | RR(3) | ... ) 546 where "|" denotes concatenation. 548 3.4. Update ZONEMD RR 550 The calculated zone digest is inserted into the placeholder ZONEMD 551 RR. Repeat for each digest if multiple digests are to be published. 553 If the zone is signed with DNSSEC, the RRSIG record(s) covering the 554 ZONEMD RRSet MUST then be added or updated. Because the ZONEMD 555 placeholder was added prior to signing, the zone will already have 556 the appropriate denial-of-existence (NSEC, NSEC3) records. 558 Some DNSSEC implementations (especially "online signing") might 559 update the SOA serial number whenever a new signature is made. To 560 preserve the calculated digest, generation of a ZONEMD signature MUST 561 NOT also result in a change to the SOA serial number. The ZONEMD RR 562 and the matching SOA MUST be published at the same time. 564 4. Verifying Zone Digest 566 The recipient of a zone that has a ZONEMD RR verifies the zone by 567 calculating the digest as follows. If multiple ZONEMD RRs are 568 present in the zone, e.g., during an algorithm rollover, a match 569 using any one of the recipient's supported Schemes and Hash 570 Algorithms is sufficient to verify the zone. The verifier MAY ignore 571 a ZONEMD RR if its Scheme and Hash Algorithm violates local policy. 573 1. The verifier MUST first determine whether or not to expect DNSSEC 574 records in the zone. This is done by examining locally 575 configured trust anchors, or querying for (and validating) DS RRs 576 in the parent zone. For zones that are provably insecure, or if 577 DNSSEC validation is not performed, digest verification continues 578 at step 4 below. 580 2. For zones that are provably secure, the existence of the apex 581 ZONEMD record MUST be verified. If the ZONEMD record provably 582 does not exist, digest verification cannot occur. If the ZONEMD 583 record does provably exist, but is not found in the zone, digest 584 verification MUST NOT be considered successful. 586 3. For zones that are provably secure, the SOA and ZONEMD RRSets 587 MUST have valid signatures, chaining up to a trust anchor. If 588 DNSSEC validation of the SOA or ZONEMD records fails, digest 589 verification MUST NOT be considered successful. 591 4. When multiple ZONEMD RRs are present, each MUST specify a unique 592 Scheme and Hash Algorithm tuple. If the ZONEMD RRSet contains 593 more than one RR with the same Scheme and Hash Algorithm, digest 594 verification for those ZONEMD RRs MUST NOT be considered 595 successful. 597 5. Loop over all apex ZONEMD RRs and perform the following steps: 599 A. The SOA Serial field MUST exactly match the ZONEMD Serial 600 field. If the fields do not match, digest verification MUST 601 NOT be considered successful with this ZONEMD RR. 603 B. The Scheme field MUST be checked. If the verifier does not 604 support the given scheme, verification MUST NOT be considered 605 successful with this ZONEMD RR and it SHOULD report that the 606 RR's digest could not be verified due to an unsupported 607 scheme. 609 C. The Hash Algorithm field MUST be checked. If the verifier 610 does not support the given hash algorithm, verification MUST 611 NOT be considered successful with this ZONEMD RR and it 612 SHOULD report that the RR's digest could not be verified due 613 to an unsupported algorithm. 615 D. The Digest field size MUST be checked. If the size of the 616 given Digest field is smaller than 12 octets, or if the size 617 is not equal to the size expected for the corresponding Hash 618 Algorithm, verification MUST NOT be considered successful 619 with this ZONEMD RR and the verifier SHOULD report that the 620 RR's digest could not be verified to to an incorrect digest 621 length. 623 E. The zone digest is computed over the zone data as described 624 in Section 3.3, using the Scheme and Hash Algorithm for the 625 current ZONEMD RR. 627 F. The computed digest is compared to the received digest. If 628 the two digest values match, verification is considered 629 successful. Otherwise, verification MUST NOT be considered 630 successful for this ZONEMD RR. 632 5. IANA Considerations 634 5.1. ZONEMD RRtype 636 This document defines a new DNS RR type, ZONEMD, whose value 63 has 637 been allocated by IANA from the "Resource Record (RR) TYPEs" 638 subregistry of the "Domain Name System (DNS) Parameters" registry: 640 Type: ZONEMD 642 Value: 63 644 Meaning: Message Digest Over Zone Data 646 Reference: [this document] 648 5.2. ZONEMD Scheme 650 IANA is requested to create a new registry on the "Domain Name System 651 (DNS) Parameters" web page as follows: 653 Registry Name: ZONEMD Schemes 655 Registration Procedure: Specification Required 657 Reference: [this document] 658 +---------+---------------+----------+------------------+-----------+ 659 | Value | Description | Mnemonic | Implementation | Reference | 660 | | | | Requirement | | 661 +---------+---------------+----------+------------------+-----------+ 662 | 0 | Reserved | | | | 663 | 1 | Simple ZONEMD | SIMPLE | MUST | [this | 664 | | collation | | | document] | 665 | 2-239 | Unassigned | | | | 666 | 240-254 | Private Use | N/A | N/A | [this | 667 | | | | | document] | 668 | 255 | Reserved | | | | 669 +---------+---------------+----------+------------------+-----------+ 671 Table 1: ZONEMD Scheme Registry 673 5.3. ZONEMD Hash Algorithm 675 IANA is requested to create a new registry on the "Domain Name System 676 (DNS) Parameters" web page as follows: 678 Registry Name: ZONEMD Hash Algorithms 680 Registration Procedure: Specification Required 682 Reference: [this document] 684 +---------+-------------+----------+-------------------+------------+ 685 | Value | Description | Mnemonic | Implementation | Reference | 686 | | | | Requirement | | 687 +---------+-------------+----------+-------------------+------------+ 688 | 0 | Reserved | | | | 689 | 1 | SHA-384 | SHA384 | MUST | [this | 690 | | | | | document] | 691 | 2 | SHA-512 | SHA512 | SHOULD | [this | 692 | | | | | document] | 693 | 3-239 | Unassigned | | | | 694 | 240-254 | Private Use | N/A | N/A | [his | 695 | | | | | document] | 696 | 255 | Reserved | | | | 697 +---------+-------------+----------+-------------------+------------+ 699 Table 2: ZONEMD Hash Algorithm Registry 701 The IANA policy for assigning new values to the ZONEMD Hash Algorithm 702 registry shall be Specification Required. 704 6. Security Considerations 706 6.1. Attacks Against the Zone Digest 708 The zone digest allows the recipient of a zone to verify its 709 integrity. In conjunction with DNSSEC, the recipient can 710 authenticate that it is as published by the zone originator. 712 An attacker, whose goal is to modify zone content before it is used 713 by the victim, may consider a number of different approaches. 715 The attacker might perform a downgrade attack to an unsigned zone. 716 This is why Section 4 talks about determining whether or not to 717 expect DNSSEC signatures for the zone in step 1. 719 The attacker might perform a downgrade attack by removing one or more 720 ZONEMD records. Such a removal is detectable only with DNSSEC 721 validation and is why Section 4 talks about checking denial-of- 722 existence proofs in step 2 and signature validation in step 3. 724 The attacker might alter the Scheme, Hash Algorithm, or Digest fields 725 of the ZONEMD record. Such modifications are detectable only with 726 DNSSEC validation. 728 6.2. DNSSESC Timing Considerations 730 As with all DNSSEC signatures, the ability to perform signature 731 validation of a ZONEMD record is limited in time. If the DS 732 record(s) or trust anchors for the zone to be verified are no longer 733 available, the recipient cannot validate the ZONEMD RRSet. This 734 could happen even if the ZONEMD signature is still current (not 735 expired), since the zone's DS record(s) may have been withdrawn 736 following a KSK rollover. 738 For zones where it may be important to validate a ZONEMD RRSet 739 through its entire signature validity period, the zone operator 740 should ensure that KSK rollover timing takes this into consideration. 742 6.3. Attacks Utilizing ZONEMD Queries 744 Nothing in this specification prevents clients from making, and 745 servers from responding to, ZONEMD queries. Servers SHOULD NOT 746 calculate zone digests dynamically (for each query) as this can be 747 used as a CPU resource exhaustion attack. 749 ZONEMD responses could be used in a distributed denial-of-service 750 amplification attack. The ZONEMD RR is moderately sized, much like 751 the DS RR. A single ZONEMD RR contributes approximately 40 to 65 752 octets to a DNS response, for digest types defined herein. Other RR 753 types, such as DNSKEY, can result in larger amplification effects. 755 6.4. Resilience and Fragility 757 ZONEMD is used to detect incomplete or corrupted zone data prior to 758 its use, thereby increasing resilience by not using corrupt data, but 759 also introduces some denial-of-service fragility by making good data 760 in a zone unavailable if some other data is missing or corrupt. 761 Publishers and consumers of zones containing ZONEMD records should be 762 aware of these tradeoffs. While the intention is to secure the zone 763 data, misconfigurations or implementation bugs are generally 764 indistinguishable from intentional tampering, and could lead to 765 service failures when verification is performed automatically. 767 Zone publishers may want to deploy ZONEMD gradually, perhaps by 768 utilizing one of the private use hash algorithms listed in 769 Section 5.3. Similarly, recipients may want to initially configure 770 verification failures only as a warning, and later as an error after 771 gaining experience and confidence with the feature. 773 7. Performance Considerations 775 This section is provided to make zone publishers aware of the 776 performance requirements and implications of including ZONEMD RRs in 777 a zone. 779 7.1. SIMPLE SHA384 781 As mentioned previously, the SIMPLE scheme may be impractical for use 782 in zones that are either large or highly dynamic. Zone publishers 783 should carefully consider the use of ZONEMD in such zones, since it 784 might cause consumers of zone data (e.g., secondary name servers) to 785 expend resources on digest calculation. For such use cases, it is 786 recommended that ZONEMD only be used when digest calculation time is 787 significantly less than propagation times and update intervals. 789 The authors' implementation (Appendix B.1) includes an option to 790 record and report CPU usage of its operation. The software was used 791 to generate digests for more than 800 TLD zones available from 792 [CZDS]. The table below summarizes the results for the SIMPLE scheme 793 and SHA384 hash algorithm grouped by zone size. The Rate column is 794 the mean amount of time per RR to calculate the digest, running on 795 commodity hardware in early 2020. 797 +---------------------+----------------+ 798 | Zone Size (RRs) | Rate (msec/RR) | 799 +---------------------+----------------+ 800 | 10 - 99 | 0.00683 | 801 | 100 - 999 | 0.00551 | 802 | 1000 - 9999 | 0.00505 | 803 | 10000 - 99999 | 0.00602 | 804 | 100000 - 999999 | 0.00845 | 805 | 1000000 - 9999999 | 0.0108 | 806 | 10000000 - 99999999 | 0.0148 | 807 +---------------------+----------------+ 809 For example, based on the above table, it takes approximately 0.13 810 seconds to calculate a SIMPLE SHA384 digest for a zone with 22,000 811 RRs, and about 2.5 seconds for a zone with 300,000 RRs. 813 These benchmarks attempt to emulate a worst-case scenario and take 814 into account the time required to canonicalize the zone for 815 processing. Each of the 800+ zones were measured three times, and 816 then averaged, with a different random sorting of the input data 817 prior to each measurement. 819 8. Privacy Considerations 821 This specification has no impact on user privacy. 823 9. Acknowledgments 825 The authors wish to thank David Blacka, Scott Hollenbeck, and Rick 826 Wilhelm for providing feedback on early drafts of this document. 827 Additionally, they thank Joe Abley, Mark Andrews, Ralph Dolmans, 828 Donald Eastlake, Richard Gibson, Olafur Gudmundsson, Bob Harold, Paul 829 Hoffman, Evan Hunt, Shumon Huque, Tatuya Jinmei, Mike St. Johns, Burt 830 Kaliski, Shane Kerr, Matt Larson, Barry Leiba, John Levine, Ed Lewis, 831 Matt Pounsett, Mukund Sivaraman, Petr Spacek, Ondrej Sury, Willem 832 Toorop, Florian Weimer, Tim Wicinski, Wouter Wijngaards, Paul 833 Wouters, and other members of the DNS working group for their input. 835 10. Change Log 837 RFC Editor: Please remove this section before publication. 839 This section lists substantial changes to the document as it is being 840 worked on. 842 From -00 to -01: 844 o Removed requirement to sort by RR CLASS. 846 o Added Kumari and Hardaker as coauthors. 848 o Added Change Log section. 850 o Minor clarifications and grammatical edits. 852 From -01 to -02: 854 o Emphasize desire for data security over channel security. 856 o Expanded motivation into its own subsection. 858 o Removed discussion topic whether or not to include serial in 859 ZONEMD. 861 o Clarified that a zone's NS records always sort before the SOA 862 record. 864 o Clarified that all records in the zone must are digested, except 865 as specified in the exclusion rules. 867 o Added for discussion out-of-zone and occluded records. 869 o Clarified that update of ZONEMD signature must not cause a serial 870 number change. 872 o Added persons to acknowledgments. 874 From -02 to -03: 876 o Added recommendation to set ZONEMD TTL to SOA TTL. 878 o Clarified that digest input uses uncompressed names. 880 o Updated Implementations section. 882 o Changed intended status from Standards Track to Experimental and 883 added Scope of Experiment section. 885 o Updated Motivation, Introduction, and Design Overview sections in 886 response to working group discussion. 888 o Gave ZONEMD digest types their own status, separate from DS digest 889 types. Request IANA to create a registry. 891 o Added Reserved field for future work supporting dynamic updates. 893 o Be more rigorous about having just ONE ZONEMD record in the zone. 895 o Expanded use cases. 897 From -03 to -04: 899 o Added an appendix with example zones and digests. 901 o Clarified that only apex ZONEMD RRs shall be processed. 903 From -04 to -05: 905 o Made SHA384 the only supported ZONEMD digest type. 907 o Disassociated ZONEMD digest types from DS digest types. 909 o Updates to Introduction based on list feedback. 911 o Changed "zone file" to "zone" everywhere. 913 o Restored text about why ZONEMD has a Serial field. 915 o Clarified ordering of RRSets having same owner to be numerically 916 ascending. 918 o Clarified that all duplicate RRs (not just SOA) must be suppressed 919 in digest calculation. 921 o Clarified that the Reserved field must be set to zero and checked 922 for zero in verification. 924 o Clarified that occluded data must be included. 926 o Clarified procedure for verification, using temporary location for 927 received digest. 929 o Explained why Reserved field is 8-bits. 931 o IANA Considerations section now more specific. 933 o Added complex zone to examples. 935 o 937 From -05 to -06: 939 o RR type code 63 was assigned to ZONEMD by IANA. 941 From -06 to -07: 943 o Fixed mistakes in ZONEMD examples. 945 o Added private use Digest Type values 240-254. 947 o Clarified that Digest field must not be empty. 949 From -07 to draft-ietf-dnsop-dns-zone-digest-00: 951 o Adopted by dnsop. 953 o Clarified further that non-apex ZONEMD RRs have no meaning. 955 o Changed "provably [un]signed" to "provably [in]secure". 957 o Allow multiple ZONEMD RRs to support algorithm agility/rollovers. 959 o Describe verification when there are multiple ZONEMD RRs. 961 From -00 to -01: 963 o Simplified requirements around verifying multiple digests. Any 964 one match is sufficient. 966 o Updated implementation notes. 968 o Both implementations produce expected results on examples given in 969 this document. 971 From -01 to -02: 973 o Changed the name of the Reserved field to Parameter. 975 o Changed the name of Digest Type 1 from SHA384 to SHA384-STABLE. 977 o The meaning of the Parameter field now depends on Digest Type. 979 o No longer require Parameter field to be zero in verification. 981 o Updated a rule from earlier versions that said multiple ZONEMD RRs 982 were not allowed. 984 From -02 to -03: 986 o Changed the name of Digest Type 1 from SHA384-STABLE to 987 SHA384-SIMPLE. 989 o Changed document status from Experimental to Standards Track. 991 o Removed Scope of Experimentation section. 993 From -03 to -04: 995 o Addressing WGLC feedback. 997 o Changed from "Digest Type + Paramter" to "Scheme + Hash 998 Algorithm". This should make it more obvious how ZONEMD can be 999 expanded in the future with new schemes and hash algorithms, while 1000 sacrificing some of the flexibility that the Parameter was 1001 intended to provide. 1003 o Note: old RDATA fields: Serial, Digest Type, Parameter, Digest. 1005 o Note: new RDATA fields: Serial, Scheme, Hash Algorithm, Digest. 1007 o Add new IANA requirement for a Scheme registry. 1009 o Rearranged some sections and separated scheme-specific aspects 1010 from general aspects of digest calculation. 1012 o When discussing multiple ZONEMD RRs, allow for Scheme, as well as 1013 Hash Algorithm, transition. 1015 o Added Performance Considerations section with some benchmarks. 1017 o Further clarifications about non-apex ZONEMD RRs. 1019 o Clarified inclusion rule for duplicate RRs. 1021 o Removed or lowercased some inappropriately used RFC 2119 key 1022 words. 1024 o Clarified that all ZONEMD RRs, even for unsupported hash 1025 algorithms, must be zeroized during digest calculation. 1027 o Added Resilience and Fragility to security considerations. 1029 o Updated examples since changes in this version result in different 1030 hash values. 1032 From -04 to -05: 1034 o Clarifications about non-apex and multiple ZONEMD RRs. 1036 o Clarifications about benchmark results. 1038 o Don't compute ZONEMD on-the-fly. 1040 o Specification Required for updates to ZONEMD protocol registries. 1042 o Other rewording based on WGLC feedback. 1044 o Updated RFC numbers for some references. 1046 o Use documentation IP addresses instead of loopback. 1048 o Updated examples in the appendix. 1050 From -05 to -06: 1052 o Per WG suggestion, no longer include any apex ZONEMD record in 1053 digest calculation. 1055 o Updated examples in the appendix. 1057 o Clarified verification procedure by describing a loop over all 1058 ZONEMD RRs. 1060 From -06 to -07: 1062 o Added NIC Chile Labs implementation. 1064 From -07 to -08: 1066 o Update an author's affiliation. 1068 o Clarified why placeholder RRs are still important (for NSEC/ 1069 NSEC3). 1071 o Moved subsection ("Order of RRSets Having the Same Owner Name") 1072 with single sentence paragraph up into parent section. 1074 From -08 to -09: 1076 o Moved format, ordering, inclusion/exclusion into a sub section 1077 specific to the SIMPLE scheme. 1079 o Further clarified rules about multiple ZONEMD RRs (AD comments). 1081 o Reworded rules about processing of duplicate zone RRs (AD 1082 comments). 1084 o Removed sentence about optional zeroing of digest prior to 1085 calculation (AD comments). 1087 o Other minor changes (AD comments). 1089 From -09 to -10: 1091 o Add clarification and reference to on-disk modification / 1092 corruption of zone files. 1094 o Added concerns that timing of KSK rollovers could affect 1095 validation of ZONEMD record. 1097 o Addressed SECDIR review and accepted most proposed edits. 1099 o From SECDIR review, require minimum digest length of 12 octets. 1101 o From SECDIR review, add SHA512 has hash algorithm 2. 1103 o From SECDIR review, say that ZONEMD RRs MAY be ignored by local 1104 policy. 1106 o Moved Implementation Status to an appendix with the intention to 1107 retain it in RFC. 1109 o In registry tables, changed Status column to Implementation 1110 Requirement. 1112 From -10 to -11: 1114 o Fixed people's names in the acknowledgments section (blush) 1116 o Say "has not been modified between origination and retrieval." 1118 o Say that ZONEMD TTL doesn't matter during verification. 1120 o Further clarification that the SHA-384 and SHA-512 hashes are not 1121 truncated. Future algs might be truncated, but never below 96 1122 bits. 1124 11. References 1126 11.1. Normative References 1128 [RFC1034] Mockapetris, P., "Domain names - concepts and facilities", 1129 STD 13, RFC 1034, DOI 10.17487/RFC1034, November 1987, 1130 . 1132 [RFC1035] Mockapetris, P., "Domain names - implementation and 1133 specification", STD 13, RFC 1035, DOI 10.17487/RFC1035, 1134 November 1987, . 1136 [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate 1137 Requirement Levels", BCP 14, RFC 2119, 1138 DOI 10.17487/RFC2119, March 1997, 1139 . 1141 [RFC4034] Arends, R., Austein, R., Larson, M., Massey, D., and S. 1142 Rose, "Resource Records for the DNS Security Extensions", 1143 RFC 4034, DOI 10.17487/RFC4034, March 2005, 1144 . 1146 [RFC6234] Eastlake 3rd, D. and T. Hansen, "US Secure Hash Algorithms 1147 (SHA and SHA-based HMAC and HKDF)", RFC 6234, 1148 DOI 10.17487/RFC6234, May 2011, 1149 . 1151 [RFC8174] Leiba, B., "Ambiguity of Uppercase vs Lowercase in RFC 1152 2119 Key Words", BCP 14, RFC 8174, DOI 10.17487/RFC8174, 1153 May 2017, . 1155 11.2. Informative References 1157 [CZDS] Internet Corporation for Assigned Names and Numbers, 1158 "Centralized Zone Data Service", October 2018, 1159 . 1161 [disk-full-failure] 1162 DENIC, "Background of the Partial Failure of the Name 1163 Service for .de Domains", May 2010, 1164 . 1167 [DnsTools] 1168 NIC Chile Labs, "DNS tools for zone signature (file, 1169 pkcs11-hsm) and validation, and zone digest (ZONEMD)", 1170 April 2020, . 1172 [InterNIC] 1173 ICANN, "InterNIC FTP site", May 2018, 1174 . 1176 [ldns-zone-digest] 1177 Verisign, "Implementation of Message Digests for DNS Zones 1178 using the ldns library", July 2018, 1179 . 1181 [RFC1995] Ohta, M., "Incremental Zone Transfer in DNS", RFC 1995, 1182 DOI 10.17487/RFC1995, August 1996, 1183 . 1185 [RFC2065] Eastlake 3rd, D. and C. Kaufman, "Domain Name System 1186 Security Extensions", RFC 2065, DOI 10.17487/RFC2065, 1187 January 1997, . 1189 [RFC2136] Vixie, P., Ed., Thomson, S., Rekhter, Y., and J. Bound, 1190 "Dynamic Updates in the Domain Name System (DNS UPDATE)", 1191 RFC 2136, DOI 10.17487/RFC2136, April 1997, 1192 . 1194 [RFC2535] Eastlake 3rd, D., "Domain Name System Security 1195 Extensions", RFC 2535, DOI 10.17487/RFC2535, March 1999, 1196 . 1198 [RFC2845] Vixie, P., Gudmundsson, O., Eastlake 3rd, D., and B. 1199 Wellington, "Secret Key Transaction Authentication for DNS 1200 (TSIG)", RFC 2845, DOI 10.17487/RFC2845, May 2000, 1201 . 1203 [RFC2931] Eastlake 3rd, D., "DNS Request and Transaction Signatures 1204 ( SIG(0)s )", RFC 2931, DOI 10.17487/RFC2931, September 1205 2000, . 1207 [RFC4880] Callas, J., Donnerhacke, L., Finney, H., Shaw, D., and R. 1208 Thayer, "OpenPGP Message Format", RFC 4880, 1209 DOI 10.17487/RFC4880, November 2007, 1210 . 1212 [RFC5751] Ramsdell, B. and S. Turner, "Secure/Multipurpose Internet 1213 Mail Extensions (S/MIME) Version 3.2 Message 1214 Specification", RFC 5751, DOI 10.17487/RFC5751, January 1215 2010, . 1217 [RFC5936] Lewis, E. and A. Hoenes, Ed., "DNS Zone Transfer Protocol 1218 (AXFR)", RFC 5936, DOI 10.17487/RFC5936, June 2010, 1219 . 1221 [RFC7696] Housley, R., "Guidelines for Cryptographic Algorithm 1222 Agility and Selecting Mandatory-to-Implement Algorithms", 1223 BCP 201, RFC 7696, DOI 10.17487/RFC7696, November 2015, 1224 . 1226 [RFC7858] Hu, Z., Zhu, L., Heidemann, J., Mankin, A., Wessels, D., 1227 and P. Hoffman, "Specification for DNS over Transport 1228 Layer Security (TLS)", RFC 7858, DOI 10.17487/RFC7858, May 1229 2016, . 1231 [RFC8126] Cotton, M., Leiba, B., and T. Narten, "Guidelines for 1232 Writing an IANA Considerations Section in RFCs", BCP 26, 1233 RFC 8126, DOI 10.17487/RFC8126, June 2017, 1234 . 1236 [RFC8484] Hoffman, P. and P. McManus, "DNS Queries over HTTPS 1237 (DoH)", RFC 8484, DOI 10.17487/RFC8484, October 2018, 1238 . 1240 [RFC8499] Hoffman, P., Sullivan, A., and K. Fujiwara, "DNS 1241 Terminology", BCP 219, RFC 8499, DOI 10.17487/RFC8499, 1242 January 2019, . 1244 [RFC8806] Kumari, W. and P. Hoffman, "Running a Root Server Local to 1245 a Resolver", RFC 8806, DOI 10.17487/RFC8806, June 2020, 1246 . 1248 [RootServers] 1249 Root Server Operators, "Root Server Technical Operations", 1250 July 2018, . 1252 [RPZ] Vixie, P. and V. Schryver, "DNS Response Policy Zones 1253 (RPZ)", draft-vixie-dnsop-dns-rpz-00 (work in progress), 1254 June 2018, . 1257 [ZoneDigestHackathon] 1258 Kerr, S., "Prototype implementation of ZONEMD for the IETF 1259 102 hackathon in Python", July 2018, 1260 . 1262 Appendix A. Example Zones With Digests 1264 This appendix contains example zones with accurate ZONEMD records. 1265 These can be used to verify an implementation of the zone digest 1266 protocol. 1268 A.1. Simple EXAMPLE Zone 1270 Here, the EXAMPLE zone contains an SOA record, NS and glue records, 1271 and a ZONEMD record. 1273 example. 86400 IN SOA ns1 admin 2018031900 ( 1274 1800 900 604800 86400 ) 1275 86400 IN NS ns1 1276 86400 IN NS ns2 1277 86400 IN ZONEMD 2018031900 1 1 ( 1278 c68090d90a7aed71 1279 6bc459f9340e3d7c 1280 1370d4d24b7e2fc3 1281 a1ddc0b9a87153b9 1282 a9713b3c9ae5cc27 1283 777f98b8e730044c ) 1284 ns1 3600 IN A 203.0.113.63 1285 ns2 3600 IN AAAA 2001:db8::63 1287 A.2. Complex EXAMPLE Zone 1289 Here, the EXAMPLE zone contains duplicate RRs, and an occluded RR, 1290 and one out-of-zone RR. 1292 example. 86400 IN SOA ns1 admin 2018031900 ( 1293 1800 900 604800 86400 ) 1294 86400 IN NS ns1 1295 86400 IN NS ns2 1296 86400 IN ZONEMD 2018031900 1 1 ( 1297 31cefb03814f5062 1298 ad12fa951ba0ef5f 1299 8da6ae354a415767 1300 246f7dc932ceb1e7 1301 42a2108f529db6a3 1302 3a11c01493de358d ) 1303 ns1 3600 IN A 203.0.113.63 1304 ns2 3600 IN AAAA 2001:db8::63 1305 occluded.sub 7200 IN TXT "I'm occluded but must be digested" 1306 sub 7200 IN NS ns1 1307 duplicate 300 IN TXT "I must be digested just once" 1308 duplicate 300 IN TXT "I must be digested just once" 1309 foo.test. 555 IN TXT "out-of-zone data must be excluded" 1310 non-apex 900 IN ZONEMD 2018031900 1 1 ( 1311 616c6c6f77656420 1312 6275742069676e6f 1313 7265642e20616c6c 1314 6f77656420627574 1315 2069676e6f726564 1316 2e20616c6c6f7765 ) 1318 A.3. EXAMPLE Zone with multiple digests 1320 Here, the EXAMPLE zone contains multiple ZONEMD records. It has both 1321 SHA384 and SHA512 digests using the SIMPLE scheme. It also includes 1322 ZONEMD records with Scheme and Hash Algorithm values in the private 1323 range (240-254). These additional private-range digests are not 1324 verifiable. 1326 example. 86400 IN SOA ns1 admin 2018031900 ( 1327 1800 900 604800 86400 ) 1328 example. 86400 IN NS ns1.example. 1329 example. 86400 IN NS ns2.example. 1330 example. 86400 IN ZONEMD 2018031900 1 1 ( 1331 62e6cf51b02e54b9 1332 b5f967d547ce4313 1333 6792901f9f88e637 1334 493daaf401c92c27 1335 9dd10f0edb1c56f8 1336 080211f8480ee306 ) 1337 example. 86400 IN ZONEMD 2018031900 1 2 ( 1338 08cfa1115c7b948c 1339 4163a901270395ea 1340 226a930cd2cbcf2f 1341 a9a5e6eb85f37c8a 1342 4e114d884e66f176 1343 eab121cb02db7d65 1344 2e0cc4827e7a3204 1345 f166b47e5613fd27 ) 1346 example. 86400 IN ZONEMD 2018031900 1 240 ( 1347 e2d523f654b9422a 1348 96c5a8f44607bbee ) 1349 example. 86400 IN ZONEMD 2018031900 241 1 ( 1350 e1846540e33a9e41 1351 89792d18d5d131f6 1352 05fc283e ) 1353 ns1.example. 3600 IN A 203.0.113.63 1354 ns2.example. 86400 IN TXT "This example has multiple digests" 1355 ns2.example. 3600 IN AAAA 2001:db8::63 1357 A.4. The URI.ARPA Zone 1359 The URI.ARPA zone retrieved 2018-10-21. Note this sample zone has 1360 (expired) signatures, but no signature for the ZONEMD RR. 1362 ; <<>> DiG 9.9.4 <<>> @lax.xfr.dns.icann.org uri.arpa axfr 1363 ; (2 servers found) 1364 ;; global options: +cmd 1365 uri.arpa. 3600 IN SOA sns.dns.icann.org. ( 1366 noc.dns.icann.org. 2018100702 10800 3600 1209600 3600 ) 1367 uri.arpa. 3600 IN RRSIG NSEC 8 2 3600 ( 1368 20181028142623 20181007205525 47155 uri.arpa. 1369 eEC4w/oXLR1Epwgv4MBiDtSBsXhqrJVvJWUpbX8XpetAvD35bxwNCUTi 1370 /pAJVUXefegWeiriD2rkTgCBCMmn7YQIm3gdR+HjY/+o3BXNQnz97f+e 1371 HAE9EDDzoNVfL1PyV/2fde9tDeUuAGVVwmD399NGq9jWYMRpyri2kysr q/g= ) 1372 uri.arpa. 86400 IN RRSIG NS 8 2 86400 ( 1373 20181028172020 20181007175821 47155 uri.arpa. 1374 ATyV2A2A8ZoggC+68u4GuP5MOUuR+2rr3eWOkEU55zAHld/7FiBxl4ln 1375 4byJYy7NudUwlMOEXajqFZE7DVl8PpcvrP3HeeGaVzKqaWj+aus0jbKF 1376 Bsvs2b1qDZemBfkz/IfAhUTJKnto0vSUicJKfItu0GjyYNJCz2CqEuGD Wxc= ) 1377 uri.arpa. 600 IN RRSIG MX 8 2 600 ( 1378 20181028170556 20181007175821 47155 uri.arpa. 1379 e7/r3KXDohX1lyVavetFFObp8fB8aXT76HnN9KCQDxSnSghNM83UQV0t 1380 lTtD8JVeN1mCvcNFZpagwIgB7XhTtm6Beur/m5ES+4uSnVeS6Q66HBZK 1381 A3mR95IpevuVIZvvJ+GcCAQpBo6KRODYvJ/c/ZG6sfYWkZ7qg/Em5/+3 4UI= ) 1382 uri.arpa. 3600 IN RRSIG DNSKEY 8 2 3600 ( 1383 20181028152832 20181007175821 15796 uri.arpa. 1384 nzpbnh0OqsgBBP8St28pLvPEQ3wZAUdEBuUwil+rtjjWlYYiqjPxZ286 1385 XF4Rq1usfV5x71jZz5IqswOaQgia91ylodFpLuXD6FTGs2nXGhNKkg1V 1386 chHgtwj70mXU72GefVgo8TxrFYzxuEFP5ZTP92t97FVWVVyyFd86sbbR 1387 6DZj3uA2wEvqBVLECgJLrMQ9Yy7MueJl3UA4h4E6zO2JY9Yp0W9woq0B 1388 dqkkwYTwzogyYffPmGAJG91RJ2h6cHtFjEZe2MnaY2glqniZ0WT9vXXd 1389 uFPm0KD9U77Ac+ZtctAF9tsZwSdAoL365E2L1usZbA+K0BnPPqGFJRJk 1390 5R0A1w== ) 1391 uri.arpa. 3600 IN RRSIG DNSKEY 8 2 3600 ( 1392 20181028152832 20181007175821 55480 uri.arpa. 1393 lWtQV/5szQjkXmbcD47/+rOW8kJPksRFHlzxxmzt906+DBYyfrH6uq5X 1394 nHvrUlQO6M12uhqDeL+bDFVgqSpNy+42/OaZvaK3J8EzPZVBHPJykKMV 1395 63T83aAiJrAyHzOaEdmzLCpalqcEE2ImzlLHSafManRfJL8Yuv+JDZFj 1396 2WDWfEcUuwkmIZWX11zxp+DxwzyUlRl7x4+ok5iKZWIg5UnBAf6B8T75 1397 WnXzlhCw3F2pXI0a5LYg71L3Tp/xhjN6Yy9jGlIRf5BjB59X2zra3a2R 1398 PkI09SSnuEwHyF1mDaV5BmQrLGRnCjvwXA7ho2m+vv4SP5dUdXf+GTeA 1399 1HeBfw== ) 1400 uri.arpa. 3600 IN RRSIG SOA 8 2 3600 ( 1401 20181029114753 20181008222815 47155 uri.arpa. 1402 qn8yBNoHDjGdT79U2Wu9IIahoS0YPOgYP8lG+qwPcrZ1BwGiHywuoUa2 1403 Mx6BWZlg+HDyaxj2iOmox+IIqoUHhXUbO7IUkJFlgrOKCgAR2twDHrXu 1404 9BUQHy9SoV16wYm3kBTEPyxW5FFm8vcdnKAF7sxSY8BbaYNpRIEjDx4A JUc= ) 1405 uri.arpa. 3600 IN NSEC ftp.uri.arpa. NS SOA ( 1406 MX RRSIG NSEC DNSKEY ) 1407 uri.arpa. 86400 IN NS a.iana-servers.net. 1408 uri.arpa. 86400 IN NS b.iana-servers.net. 1409 uri.arpa. 86400 IN NS c.iana-servers.net. 1410 uri.arpa. 86400 IN NS ns2.lacnic.net. 1411 uri.arpa. 86400 IN NS sec3.apnic.net. 1412 uri.arpa. 600 IN MX 10 pechora.icann.org. 1413 uri.arpa. 3600 IN DNSKEY 256 3 8 ( 1414 AwEAAcBi7tSart2J599zbYWspMNGN70IBWb4ziqyQYH9MTB/VCz6WyUK 1415 uXunwiJJbbQ3bcLqTLWEw134B6cTMHrZpjTAb5WAwg4XcWUu8mdcPTiL 1416 Bl6qVRlRD0WiFCTzuYUfkwsh1Rbr7rvrxSQhF5rh71zSpwV5jjjp65Wx 1417 SdJjlH0B ) 1418 uri.arpa. 3600 IN DNSKEY 257 3 8 ( 1419 AwEAAbNVv6ulgRdO31MtAehz7j3ALRjwZglWesnzvllQl/+hBRZr9QoY 1420 cO2I+DkO4Q1NKxox4DUIxj8SxPO3GwDuOFR9q2/CFi2O0mZjafbdYtWc 1421 3zSdBbi3q0cwCIx7GuG9eqlL+pg7mdk9dgdNZfHwB0LnqTD8ebLPsrO/ 1422 Id7kBaiqYOfMlZnh2fp+2h6OOJZHtY0DK1UlssyB5PKsE0tVzo5s6zo9 1423 iXKe5u+8WTMaGDY49vG80JPAKE7ezMiH/NZcUMiE0PRZ8D3foq2dYuS5 1424 ym+vA83Z7v8A+Rwh4UGnjxKB8zmr803V0ASAmHz/gwH5Vb0nH+LObwFt 1425 l3wpbp+Wpm8= ) 1426 uri.arpa. 3600 IN DNSKEY 257 3 8 ( 1427 AwEAAbwnFTakCvaUKsXji4mgmxZUJi1IygbnGahbkmFEa0L16J+TchKR 1428 wcgzVfsxUGa2MmeA4hgkAooC3uy+tTmoMsgy8uq/JAj24DjiHzd46LfD 1429 FK/qMidVqFpYSHeq2Vv5ojkuIsx4oe4KsafGWYNOczKZgH5loGjN2aJG 1430 mrIm++XCphOskgCsQYl65MIzuXffzJyxlAuts+ecAIiVeqRaqQfr8LRU 1431 7wIsLxinXirprtQrbor+EtvlHp9qXE6ARTZDzf4jvsNpKvLFZtmxzFf3 1432 e/UJz5eHjpwDSiZL7xE8aE1o1nGfPtJx9ZnB3bapltaJ5wY+5XOCKgY0 1433 xmJVvNQlwdE= ) 1434 ftp.uri.arpa. 3600 IN RRSIG NSEC 8 3 3600 ( 1435 20181028080856 20181007175821 47155 uri.arpa. 1436 HClGAqPxzkYkAT7Q/QNtQeB6YrkP6EPOef+9Qo5/2zngwAewXEAQiyF9 1437 jD1USJiroM11QqBS3v3aIdW/LXORs4Ez3hLcKNO1cKHsOuWAqzmE+BPP 1438 Arfh8N95jqh/q6vpaB9UtMkQ53tM2fYU1GszOLN0knxbHgDHAh2axMGH lqM= ) 1439 ftp.uri.arpa. 604800 IN RRSIG NAPTR 8 3 604800 ( 1440 20181028103644 20181007205525 47155 uri.arpa. 1441 WoLi+vZzkxaoLr2IGZnwkRvcDf6KxiWQd1WZP/U+AWnV+7MiqsWPZaf0 1442 9toRErerGoFOiOASNxZjBGJrRgjmavOM9U+LZSconP9zrNFd4dIu6kp5 1443 YxlQJ0uHOvx1ZHFCj6lAt1ACUIw04ZhMydTmi27c8MzEOMepvn7iH7r7 k7k= ) 1444 ftp.uri.arpa. 3600 IN NSEC http.uri.arpa. NAPTR ( 1445 RRSIG NSEC ) 1446 ftp.uri.arpa. 604800 IN NAPTR 0 0 "" "" ( 1447 "!^ftp://([^:/?#]*).*$!\\1!i" . ) 1448 http.uri.arpa. 3600 IN RRSIG NSEC 8 3 3600 ( 1449 20181029010647 20181007175821 47155 uri.arpa. 1450 U03NntQ73LHWpfLmUK8nMsqkwVsOGW2KdsyuHYAjqQSZvKbtmbv7HBmE 1451 H1+Ii3Z+wtfdMZBy5aC/6sHdx69BfZJs16xumycMlAy6325DKTQbIMN+ 1452 ift9GrKBC7cgCd2msF/uzSrYxxg4MJQzBPvlkwXnY3b7eJSlIXisBIn7 3b8= ) 1453 http.uri.arpa. 604800 IN RRSIG NAPTR 8 3 604800 ( 1454 20181029011815 20181007205525 47155 uri.arpa. 1455 T7mRrdag+WSmG+n22mtBSQ/0Y3v+rdDnfQV90LN5Fq32N5K2iYFajF7F 1456 Tp56oOznytfcL4fHrqOE0wRc9NWOCCUec9C7Wa1gJQcllEvgoAM+L6f0 1457 RsEjWq6+9jvlLKMXQv0xQuMX17338uoD/xiAFQSnDbiQKxwWMqVAimv5 7Zs= ) 1458 http.uri.arpa. 3600 IN NSEC mailto.uri.arpa. NAPTR ( 1459 RRSIG NSEC ) 1460 http.uri.arpa. 604800 IN NAPTR 0 0 "" "" ( 1461 "!^http://([^:/?#]*).*$!\\1!i" . ) 1463 mailto.uri.arpa. 3600 IN RRSIG NSEC 8 3 3600 ( 1464 20181028110727 20181007175821 47155 uri.arpa. 1465 GvxzVL85rEukwGqtuLxek9ipwjBMfTOFIEyJ7afC8HxVMs6mfFa/nEM/ 1466 IdFvvFg+lcYoJSQYuSAVYFl3xPbgrxVSLK125QutCFMdC/YjuZEnq5cl 1467 fQciMRD7R3+znZfm8d8u/snLV9w4D+lTBZrJJUBe1Efc8vum5vvV7819 ZoY= ) 1468 mailto.uri.arpa. 604800 IN RRSIG NAPTR 8 3 604800 ( 1469 20181028141825 20181007205525 47155 uri.arpa. 1470 MaADUgc3fc5v++M0YmqjGk3jBdfIA5RuP62hUSlPsFZO4k37erjIGCfF 1471 j+g84yc+QgbSde0PQHszl9fE/+SU5ZXiS9YdcbzSZxp2erFpZOTchrpg 1472 916T4vx6i59scodjb0l6bDyZ+mtIPrc1w6b4hUyOUTsDQoAJYxdfEuMg Vy4= ) 1473 mailto.uri.arpa. 3600 IN NSEC urn.uri.arpa. NAPTR ( 1474 RRSIG NSEC ) 1475 mailto.uri.arpa. 604800 IN NAPTR 0 0 "" "" ( 1476 "!^mailto:(.*)@(.*)$!\\2!i" . ) 1477 urn.uri.arpa. 3600 IN RRSIG NSEC 8 3 3600 ( 1478 20181028123243 20181007175821 47155 uri.arpa. 1479 Hgsw4Deops1O8uWyELGe6hpR/OEqCnTHvahlwiQkHhO5CSEQrbhmFAWe 1480 UOkmGAdTEYrSz+skLRQuITRMwzyFf4oUkZihGyhZyzHbcxWfuDc/Pd/9 1481 DSl56gdeBwy1evn5wBTms8yWQVkNtphbJH395gRqZuaJs3LD/qTyJ5Dp LvA= ) 1482 urn.uri.arpa. 604800 IN RRSIG NAPTR 8 3 604800 ( 1483 20181029071816 20181007205525 47155 uri.arpa. 1484 ALIZD0vBqAQQt40GQ0Efaj8OCyE9xSRJRdyvyn/H/wZVXFRFKrQYrLAS 1485 D/K7q6CMTOxTRCu2J8yes63WJiaJEdnh+dscXzZkmOg4n5PsgZbkvUSW 1486 BiGtxvz5jNncM0xVbkjbtByrvJQAO1cU1mnlDKe1FmVB1uLpVdA9Ib4J hMU= ) 1487 urn.uri.arpa. 3600 IN NSEC uri.arpa. NAPTR RRSIG ( 1488 NSEC ) 1489 urn.uri.arpa. 604800 IN NAPTR 0 0 "" "" ( 1490 "/urn:([^:]+)/\\1/i" . ) 1491 uri.arpa. 3600 IN SOA sns.dns.icann.org. ( 1492 noc.dns.icann.org. 2018100702 10800 3600 1209600 3600 ) 1493 ;; Query time: 66 msec 1494 ;; SERVER: 192.0.32.132#53(192.0.32.132) 1495 ;; WHEN: Sun Oct 21 20:39:28 UTC 2018 1496 ;; XFR size: 34 records (messages 1, bytes 3941) 1497 uri.arpa. 3600 IN ZONEMD 2018100702 1 1 ( 1498 1291b78ddf7669b1a39d014d87626b709b55774c5d7d58fa 1499 dc556439889a10eaf6f11d615900a4f996bd46279514e473 ) 1501 A.5. The ROOT-SERVERS.NET Zone 1503 The ROOT-SERVERS.NET zone retrieved 2018-10-21. 1505 root-servers.net. 3600000 IN SOA a.root-servers.net. ( 1506 nstld.verisign-grs.com. 2018091100 14400 7200 1209600 3600000 ) 1507 root-servers.net. 3600000 IN NS a.root-servers.net. 1508 root-servers.net. 3600000 IN NS b.root-servers.net. 1509 root-servers.net. 3600000 IN NS c.root-servers.net. 1510 root-servers.net. 3600000 IN NS d.root-servers.net. 1511 root-servers.net. 3600000 IN NS e.root-servers.net. 1512 root-servers.net. 3600000 IN NS f.root-servers.net. 1513 root-servers.net. 3600000 IN NS g.root-servers.net. 1514 root-servers.net. 3600000 IN NS h.root-servers.net. 1515 root-servers.net. 3600000 IN NS i.root-servers.net. 1516 root-servers.net. 3600000 IN NS j.root-servers.net. 1517 root-servers.net. 3600000 IN NS k.root-servers.net. 1518 root-servers.net. 3600000 IN NS l.root-servers.net. 1519 root-servers.net. 3600000 IN NS m.root-servers.net. 1520 a.root-servers.net. 3600000 IN AAAA 2001:503:ba3e::2:30 1521 a.root-servers.net. 3600000 IN A 198.41.0.4 1522 b.root-servers.net. 3600000 IN MX 20 mail.isi.edu. 1523 b.root-servers.net. 3600000 IN AAAA 2001:500:200::b 1524 b.root-servers.net. 3600000 IN A 199.9.14.201 1525 c.root-servers.net. 3600000 IN AAAA 2001:500:2::c 1526 c.root-servers.net. 3600000 IN A 192.33.4.12 1527 d.root-servers.net. 3600000 IN AAAA 2001:500:2d::d 1528 d.root-servers.net. 3600000 IN A 199.7.91.13 1529 e.root-servers.net. 3600000 IN AAAA 2001:500:a8::e 1530 e.root-servers.net. 3600000 IN A 192.203.230.10 1531 f.root-servers.net. 3600000 IN AAAA 2001:500:2f::f 1532 f.root-servers.net. 3600000 IN A 192.5.5.241 1533 g.root-servers.net. 3600000 IN AAAA 2001:500:12::d0d 1534 g.root-servers.net. 3600000 IN A 192.112.36.4 1535 h.root-servers.net. 3600000 IN AAAA 2001:500:1::53 1536 h.root-servers.net. 3600000 IN A 198.97.190.53 1537 i.root-servers.net. 3600000 IN MX 10 mx.i.root-servers.org. 1538 i.root-servers.net. 3600000 IN AAAA 2001:7fe::53 1539 i.root-servers.net. 3600000 IN A 192.36.148.17 1540 j.root-servers.net. 3600000 IN AAAA 2001:503:c27::2:30 1541 j.root-servers.net. 3600000 IN A 192.58.128.30 1542 k.root-servers.net. 3600000 IN AAAA 2001:7fd::1 1543 k.root-servers.net. 3600000 IN A 193.0.14.129 1544 l.root-servers.net. 3600000 IN AAAA 2001:500:9f::42 1545 l.root-servers.net. 3600000 IN A 199.7.83.42 1546 m.root-servers.net. 3600000 IN AAAA 2001:dc3::35 1547 m.root-servers.net. 3600000 IN A 202.12.27.33 1548 root-servers.net. 3600000 IN SOA a.root-servers.net. ( 1549 nstld.verisign-grs.com. 2018091100 14400 7200 1209600 3600000 ) 1550 root-servers.net. 3600000 IN ZONEMD 2018091100 1 1 ( 1551 f1ca0ccd91bd5573d9f431c00ee0101b2545c97602be0a97 1552 8a3b11dbfc1c776d5b3e86ae3d973d6b5349ba7f04340f79 ) 1554 Appendix B. Implementation Status 1556 RFC Editor: Please retain this section upon publication. 1558 This section records the status of known implementations of the 1559 protocol defined by this specification at the time of posting of this 1560 Internet-Draft, and is based on a proposal described in RFC 7942. 1561 The description of implementations in this section is intended to 1562 assist the IETF in its decision processes in progressing drafts to 1563 RFCs. Please note that the listing of any individual implementation 1564 here does not imply endorsement by the IETF. Furthermore, no effort 1565 has been spent to verify the information presented here that was 1566 supplied by IETF contributors. This is not intended as, and must not 1567 be construed to be, a catalog of available implementations or their 1568 features. Readers are advised to note that other implementations may 1569 exist. 1571 B.1. Authors' Implementation 1573 The authors have an open source implementation in C, using the ldns 1574 library [ldns-zone-digest]. This implementation is able to perform 1575 the following functions: 1577 o Read an input zone and output a zone with the ZONEMD placeholder. 1579 o Compute zone digest over signed zone and update the ZONEMD record. 1581 o Re-compute DNSSEC signature over the ZONEMD record. 1583 o Verify the zone digest from an input zone. 1585 This implementation does not: 1587 o Perform DNSSEC validation of the ZONEMD record during 1588 verification. 1590 B.2. Shane Kerr's Implementation 1592 Shane Kerr wrote an implementation of this specification during the 1593 IETF 102 hackathon [ZoneDigestHackathon]. This implementation is in 1594 Python and is able to perform the following functions: 1596 o Read an input zone and output a zone with ZONEMD record. 1598 o Verify the zone digest from an input zone. 1600 o Output the ZONEMD record in its defined presentation format. 1602 This implementation does not: 1604 o Re-compute DNSSEC signature over the ZONEMD record. 1606 o Perform DNSSEC validation of the ZONEMD record. 1608 B.3. NIC Chile Labs Implementation 1610 NIC Chile Labs wrote an implementation of this specification as part 1611 of "dns-tools" suite [DnsTools], which besides digesting, can also 1612 sign and verify zones. This implementation is in Go and is able to 1613 perform the following functions: 1615 o Compute zone digest over signed zone and update the ZONEMD record. 1617 o Verify the zone digest from an input zone. 1619 o Perform DNSSEC validation of the ZONEMD record during 1620 verification. 1622 o Re-compute DNSSEC signature over the ZONEMD record. 1624 Authors' Addresses 1626 Duane Wessels 1627 Verisign 1628 12061 Bluemont Way 1629 Reston, VA 20190 1631 Phone: +1 703 948-3200 1632 Email: dwessels@verisign.com 1633 URI: https://verisign.com 1635 Piet Barber 1636 Verisign 1637 12061 Bluemont Way 1638 Reston, VA 20190 1640 Phone: +1 703 948-3200 1641 Email: pbarber@verisign.com 1642 URI: https://verisign.com 1643 Matt Weinberg 1644 Amazon 1646 Email: matweinb@amazon.com 1647 URI: https://amazon.com 1649 Warren Kumari 1650 Google 1651 1600 Amphitheatre Parkway 1652 Mountain View, CA 94043 1654 Email: warren@kumari.net 1656 Wes Hardaker 1657 USC/ISI 1658 P.O. Box 382 1659 Davis, CA 95617 1661 Email: ietf@hardakers.net