idnits 2.17.00 (12 Aug 2021) /tmp/idnits30788/draft-ietf-dnsop-dns-zone-digest-09.txt: Checking boilerplate required by RFC 5378 and the IETF Trust (see https://trustee.ietf.org/license-info): ---------------------------------------------------------------------------- No issues found here. Checking nits according to https://www.ietf.org/id-info/1id-guidelines.txt: ---------------------------------------------------------------------------- No issues found here. Checking nits according to https://www.ietf.org/id-info/checklist : ---------------------------------------------------------------------------- == There are 14 instances of lines with non-RFC6890-compliant IPv4 addresses in the document. If these are example addresses, they should be changed. == There are 1 instance of lines with non-RFC3849-compliant IPv6 addresses in the document. If these are example addresses, they should be changed. Miscellaneous warnings: ---------------------------------------------------------------------------- == The copyright year in the IETF Trust and authors Copyright Line does not match the current year -- The document date (August 28, 2020) is 631 days in the past. Is this intentional? Checking references for intended status: Proposed Standard ---------------------------------------------------------------------------- (See RFCs 3967 and 4897 for information about using normative references to lower-maturity documents in RFCs) ** Downref: Normative reference to an Informational RFC: RFC 6234 -- Obsolete informational reference (is this intentional?): RFC 2065 (Obsoleted by RFC 2535) -- Obsolete informational reference (is this intentional?): RFC 2535 (Obsoleted by RFC 4033, RFC 4034, RFC 4035) -- Obsolete informational reference (is this intentional?): RFC 2845 (Obsoleted by RFC 8945) -- Obsolete informational reference (is this intentional?): RFC 5751 (Obsoleted by RFC 8551) Summary: 1 error (**), 0 flaws (~~), 3 warnings (==), 5 comments (--). 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 1, 2021 M. Weinberg 6 Amazon 7 W. Kumari 8 Google 9 W. Hardaker 10 USC/ISI 11 August 28, 2020 13 Message Digest for DNS Zones 14 draft-ietf-dnsop-dns-zone-digest-09 16 Abstract 18 This document describes a protocol and new DNS Resource Record that 19 can be used to provide a cryptographic message digest over DNS zone 20 data. The ZONEMD Resource Record conveys the digest data in the zone 21 itself. When a zone publisher includes an ZONEMD record, recipients 22 can verify the zone contents for accuracy and completeness. This 23 provides assurance that received zone data matches published data, 24 regardless of how the zone data has been transmitted and received. 26 ZONEMD is not designed to replace DNSSEC. Whereas DNSSEC protects 27 individual RRSets (DNS data with fine granularity), ZONEMD protects a 28 zone's data as a whole, whether consumed by authoritative name 29 servers, recursive name servers, or any other applications. 31 As specified at this time, ZONEMD is not designed for use in large, 32 dynamic zones due to the time and resources required for digest 33 calculation. The ZONEMD record described in this document is 34 designed so that new digest schemes may be developed in the future to 35 support large, dynamic zones. 37 Status of This Memo 39 This Internet-Draft is submitted in full conformance with the 40 provisions of BCP 78 and BCP 79. 42 Internet-Drafts are working documents of the Internet Engineering 43 Task Force (IETF). Note that other groups may also distribute 44 working documents as Internet-Drafts. The list of current Internet- 45 Drafts is at https://datatracker.ietf.org/drafts/current/. 47 Internet-Drafts are draft documents valid for a maximum of six months 48 and may be updated, replaced, or obsoleted by other documents at any 49 time. It is inappropriate to use Internet-Drafts as reference 50 material or to cite them other than as "work in progress." 52 This Internet-Draft will expire on March 1, 2021. 54 Copyright Notice 56 Copyright (c) 2020 IETF Trust and the persons identified as the 57 document authors. All rights reserved. 59 This document is subject to BCP 78 and the IETF Trust's Legal 60 Provisions Relating to IETF Documents 61 (https://trustee.ietf.org/license-info) in effect on the date of 62 publication of this document. Please review these documents 63 carefully, as they describe your rights and restrictions with respect 64 to this document. Code Components extracted from this document must 65 include Simplified BSD License text as described in Section 4.e of 66 the Trust Legal Provisions and are provided without warranty as 67 described in the Simplified BSD License. 69 Table of Contents 71 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 3 72 1.1. Motivation . . . . . . . . . . . . . . . . . . . . . . . 4 73 1.2. Design Overview . . . . . . . . . . . . . . . . . . . . . 6 74 1.3. Use Cases . . . . . . . . . . . . . . . . . . . . . . . . 6 75 1.3.1. Root Zone . . . . . . . . . . . . . . . . . . . . . . 6 76 1.3.2. Providers, Secondaries, and Anycast . . . . . . . . . 6 77 1.3.3. Response Policy Zones . . . . . . . . . . . . . . . . 7 78 1.3.4. Centralized Zone Data Service . . . . . . . . . . . . 7 79 1.3.5. General Purpose Comparison Check . . . . . . . . . . 7 80 1.4. Requirements Language . . . . . . . . . . . . . . . . . . 7 81 2. The ZONEMD Resource Record . . . . . . . . . . . . . . . . . 7 82 2.1. Non-apex ZONEMD Records . . . . . . . . . . . . . . . . . 8 83 2.2. ZONEMD RDATA Wire Format . . . . . . . . . . . . . . . . 8 84 2.2.1. The Serial Field . . . . . . . . . . . . . . . . . . 8 85 2.2.2. The Scheme Field . . . . . . . . . . . . . . . . . . 9 86 2.2.3. The Hash Algorithm Field . . . . . . . . . . . . . . 9 87 2.2.4. The Digest Field . . . . . . . . . . . . . . . . . . 9 88 2.3. ZONEMD Presentation Format . . . . . . . . . . . . . . . 9 89 2.4. ZONEMD Example . . . . . . . . . . . . . . . . . . . . . 10 90 3. Calculating the Digest . . . . . . . . . . . . . . . . . . . 10 91 3.1. Add ZONEMD Placeholder . . . . . . . . . . . . . . . . . 10 92 3.2. Optionally Sign the Zone . . . . . . . . . . . . . . . . 10 93 3.3. Scheme-Specific Processing . . . . . . . . . . . . . . . 11 94 3.3.1. The SIMPLE Scheme . . . . . . . . . . . . . . . . . . 11 95 3.3.1.1. SIMPLE Scheme RR Format . . . . . . . . . . . . . 11 96 3.3.1.2. SIMPLE Scheme RR Ordering . . . . . . . . . . . . 11 97 3.3.1.3. SIMPLE Scheme Inclusion/Exclusion Rules . . . . . 11 98 3.3.1.4. SIMPLE Scheme Digest Calculation . . . . . . . . 12 99 3.4. Update ZONEMD RR . . . . . . . . . . . . . . . . . . . . 12 100 4. Verifying Zone Digest . . . . . . . . . . . . . . . . . . . . 12 101 5. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 14 102 5.1. ZONEMD RRtype . . . . . . . . . . . . . . . . . . . . . . 14 103 5.2. ZONEMD Scheme . . . . . . . . . . . . . . . . . . . . . . 14 104 5.3. ZONEMD Hash Algorithm . . . . . . . . . . . . . . . . . . 14 105 6. Security Considerations . . . . . . . . . . . . . . . . . . . 15 106 6.1. Attacks Against the Zone Digest . . . . . . . . . . . . . 15 107 6.2. Attacks Utilizing ZONEMD Queries . . . . . . . . . . . . 15 108 6.3. Resilience and Fragility . . . . . . . . . . . . . . . . 16 109 7. Performance Considerations . . . . . . . . . . . . . . . . . 16 110 7.1. SIMPLE SHA384 . . . . . . . . . . . . . . . . . . . . . . 16 111 8. Privacy Considerations . . . . . . . . . . . . . . . . . . . 17 112 9. Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . 17 113 10. Implementation Status . . . . . . . . . . . . . . . . . . . . 17 114 10.1. Authors' Implementation . . . . . . . . . . . . . . . . 17 115 10.2. Shane Kerr's Implementation . . . . . . . . . . . . . . 18 116 10.3. NIC Chile Labs Implementation . . . . . . . . . . . . . 18 117 11. Change Log . . . . . . . . . . . . . . . . . . . . . . . . . 19 118 12. References . . . . . . . . . . . . . . . . . . . . . . . . . 24 119 12.1. Normative References . . . . . . . . . . . . . . . . . . 24 120 12.2. Informative References . . . . . . . . . . . . . . . . . 25 121 Appendix A. Example Zones With Digests . . . . . . . . . . . . . 27 122 A.1. Simple EXAMPLE Zone . . . . . . . . . . . . . . . . . . . 27 123 A.2. Complex EXAMPLE Zone . . . . . . . . . . . . . . . . . . 27 124 A.3. EXAMPLE Zone with multiple digests . . . . . . . . . . . 28 125 A.4. The URI.ARPA Zone . . . . . . . . . . . . . . . . . . . . 29 126 A.5. The ROOT-SERVERS.NET Zone . . . . . . . . . . . . . . . . 32 127 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 34 129 1. Introduction 131 In the DNS, a zone is the collection of authoritative resource 132 records (RRs) sharing a common origin ([RFC8499]). Zones are often 133 stored as files on disk in the so-called master file format 134 [RFC1034]. Zones are generally distributed among name servers using 135 the AXFR [RFC5936], and IXFR [RFC1995] protocols. Zone files can 136 also be distributed outside of the DNS, with such protocols as FTP, 137 HTTP, and rsync, and even via email. Currently there is no standard 138 way to verify the authenticity of a stand-alone zone. 140 This document introduces a new RR type that serves as a cryptographic 141 message digest of the data in a zone. It allows a receiver of the 142 zone to verify the zone's authenticity, especially when used in 143 combination with DNSSEC. This technique makes the digest a part of 144 the zone itself, allowing verification the zone as a whole, no matter 145 how it is transmitted. Furthermore, the digest is based on the wire 146 format of zone data. Thus, it is independent of presentation format, 147 such as changes in whitespace, capitalization, and comments. 149 DNSSEC provides three strong security guarantees relevant to this 150 protocol: 152 1. whether or not to expect DNSSEC records in the zone, 154 2. whether or not to expect a ZONEMD record in a signed zone, and 156 3. whether or not the ZONEMD record has been altered since it was 157 signed. 159 This specification is OPTIONAL to implement by both publishers and 160 consumers of zone data. 162 1.1. Motivation 164 The motivation for this protocol enhancement is the desire for the 165 ability to verify the authenticity of a stand-alone zone, regardless 166 of how it is transmitted. A consumer of zone data should be able to 167 verify that the data is as-published by the zone operator. 169 One approach to preventing data tampering and corruption is to secure 170 the distribution channel. The DNS has a number of features that can 171 already be used for channel security. Perhaps the most widely used 172 is DNS transaction signatures (TSIG [RFC2845]). TSIG uses shared 173 secret keys and a message digest to protect individual query and 174 response messages. It is generally used to authenticate and validate 175 UPDATE [RFC2136], AXFR [RFC5936], and IXFR [RFC1995] messages. 177 DNS Request and Transaction Signatures (SIG(0) [RFC2931]) is another 178 protocol extension designed to authenticate individual DNS 179 transactions. Whereas SIG records were originally designed to cover 180 specific RR types, SIG(0) is used to sign an entire DNS message. 181 Unlike TSIG, SIG(0) uses public key cryptography rather than shared 182 secrets. 184 The Transport Layer Security protocol suite is also designed to 185 provide channel security. One can easily imagine the distribution of 186 zones over HTTPS-enabled web servers, as well as DNS-over-HTTPS 187 [RFC8484], and perhaps even a future version of DNS-over-TLS 188 ([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 can ensure that the client receives 193 the data from the expected server, and that the data sent by the 194 server is not modified during transmission. However, they do not 195 guarantee that the server transmits the data as originally published, 196 and do 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. For these reasons, it is preferable to secure the 200 data itself. 202 Why not simply rely on DNSSEC, which provides certain data security 203 guarantees? Certainly for zones that are signed, a recipient could 204 validate all of the signed RRSets. Additionally, denial-of-existence 205 records can prove that RRSets have not been added or removed. 206 However, not all RRSets in a zone are signed. The design of DNSSEC 207 stipulates that delegations (non-apex NS records) are not signed, and 208 neither are any glue records. ZONEMD protects the integrity of 209 delegation, glue, and other records that are not otherwise covered by 210 DNSSEC. Furthermore, zones that employ NSEC3 with opt-out are 211 susceptible to the removal or addition of names between the signed 212 nodes. Whereas DNSSEC is primarily designed to protect consumers of 213 DNS response messages, this protocol is designed to protect consumers 214 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. That is, a zone signed with OpenPGP or S/MIME no longer 224 looks like a DNS zone and could not directly be loaded into a name 225 server. Once loaded the signature data is lost, so it does not 226 survive further propagation. 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, aka AXFR SIG, which is similar to the technique 232 proposed by this document. That is, it proposes ordering all 233 (signed) RRSets in a zone, hashing their contents, and then signing 234 the zone hash. The AXFR SIG is described only for use during zone 235 transfers. It did not postulate the need to validate zone data 236 distributed outside of the DNS. Furthermore, its successor, 237 [RFC2535], omits the AXFR SIG, while at the same time introducing an 238 IXFR SIG. 240 1.2. Design Overview 242 This document introduces a new Resource Record type designed to 243 convey a message digest of the content of a zone. The digest is 244 calculated at the time of zone publication. Ideally the zone is 245 signed with DNSSEC to guarantee that any modifications of the digest 246 can be detected. The procedures for digest calculation and DNSSEC 247 signing are similar. Both require data to be processed in a well- 248 defined order and format. In some cases it may be possible to 249 perform DNSSEC signing and digest calculation in parallel. 251 The zone digest is designed to be used on zones that are relatively 252 stable and have infrequent updates. As currently specified, the 253 digest is re-calculated over the entire zone content each time. This 254 specification does not provide an efficient mechanism for incremental 255 updates of zone data. It is, however, extensible so that future 256 schemes to support incremental zone digest algorithms (e.g. using 257 Merkle trees) can be accommodated. 259 It is expected that verification of a zone digest would be 260 implemented in name server software. That is, a name server can 261 verify the zone data it was given and refuse to serve a zone which 262 fails verification. For signed zones, the name server needs a trust 263 anchor to perform DNSSEC validation. For signed non-root zones, the 264 name server may need to send queries to validate a chain of trust. 265 Digest verification could also be performed externally. 267 1.3. Use Cases 269 1.3.1. 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, but not the only, way to do this. As 277 the root zone spreads beyond its traditional deployment boundaries, 278 the need for verification of the completeness of the zone contents 279 becomes increasingly important. 281 1.3.2. 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 they may not have anticipated the complexity of modern DNS service 286 provisioning which can include multiple third-party providers and 287 hundreds of anycast instances. Instead of a simple primary-to- 288 secondary zone distribution system, today it is possible to have 289 multiple levels, multiple parties, and multiple protocols involved in 290 the distribution of zone data. This complexity introduces new places 291 for problems to arise. The zone digest protects the integrity of 292 data that flows through such systems. 294 1.3.3. Response Policy Zones 296 DNS Response Policy Zones is "a method of expressing DNS response 297 policy information inside specially constructed DNS zones..." [RPZ]. 298 A number of companies provide RPZ feeds, which can be consumed by 299 name server and firewall products. Since these are zones, AXFR is 300 often, but not necessarily used for transmission. While RPZ zones 301 can certainly be signed with DNSSEC, the data is not queried 302 directly, and would not be subject to DNSSEC validation. 304 1.3.4. Centralized Zone Data Service 306 ICANN operates the Centralized Zone Data Service [CZDS], which is a 307 repository of top-level domain zone files. Users request access to 308 the system, and to individual zones, and are then able to download 309 zone data for certain uses. Adding a zone digest to these would 310 provide CZDS users with assurances that the data has not been 311 modified. Note that ZONEMD could be added to CZDS zone data 312 independently of the zone served by production name servers. 314 1.3.5. General Purpose Comparison Check 316 Since the zone digest calculation does not depend on presentation 317 format, it could be used to compare multiple copies of a zone 318 received from different sources, or copies generated by different 319 processes. 321 1.4. Requirements Language 323 The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", 324 "SHOULD", "SHOULD NOT", "RECOMMENDED", "NOT RECOMMENDED", "MAY", and 325 "OPTIONAL" in this document are to be interpreted as described in BCP 326 14 [RFC2119] [RFC8174] when, and only when, they appear in all 327 capitals, as shown here. 329 2. The ZONEMD Resource Record 331 This section describes the ZONEMD Resource Record, including its 332 fields, wire format, and presentation format. The Type value for the 333 ZONEMD RR is 63. The ZONEMD RR is class independent. The RDATA of 334 the resource record consists of four fields: Serial, Scheme, Hash 335 Algorithm, and Digest. 337 A zone MAY contain multiple ZONEMD RRs to support algorithm agility 338 [RFC7696] and rollovers. When multiple ZONEMD RRs are present, each 339 must specify a unique Scheme and Hash Algorithm tuple. It is 340 recommended that a zone include only one ZONEMD RR, unless the zone 341 publisher is in the process of transitioning to a new Scheme or Hash 342 Algorithm. 344 2.1. Non-apex ZONEMD Records 346 This specification utilizes ZONEMD RRs located at the zone apex. 347 Non-apex ZONEMD RRs are not forbidden, but have no meaning in this 348 specification. Non-apex ZONEMD RRs MUST NOT be used for 349 verification. 351 During digest calculation, non-apex ZONEMD RRs are treated like any 352 other RRs. They are digested as-is and the RR is not replaced by a 353 placeholder RR. 355 Unless explicitly stated otherwise, "ZONEMD" always refers to apex 356 records throughout this document. 358 2.2. ZONEMD RDATA Wire Format 360 The ZONEMD RDATA wire format is encoded as follows: 362 1 1 1 1 1 1 1 1 1 1 2 2 2 2 2 2 2 2 2 2 3 3 363 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 1 364 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 365 | Serial | 366 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 367 | Scheme |Hash Algorithm | | 368 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | 369 | Digest | 370 / / 371 / / 372 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 374 2.2.1. The Serial Field 376 The Serial field is a 32-bit unsigned integer in network order. It 377 is equal to the serial number from the zone's SOA record ([RFC1035] 378 section 3.3.13) for which the zone digest was generated. 380 The zone's serial number is included here in order to make DNS 381 response messages of type ZONEMD meaningful. Without the serial 382 number, a stand-alone ZONEMD digest has no association to any 383 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 At the time of this writing, SIMPLE, with value 1, is the only 392 standardized Scheme defined for ZONEMD records. The Scheme registry 393 is further described in Section 5. 395 Scheme values 240-254 are allocated for Private Use as described in 396 [RFC8126]. 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 At the time of this writing, SHA384, with value 1, is the only 404 standardized Hash Algorithm defined for ZONEMD records. The Hash 405 Algorithm registry is further described in Section 5. 407 Hash Algorithm values 240-254 are allocated for Private Use as 408 described in [RFC8126]. 410 2.2.4. The Digest Field 412 The Digest field is a variable-length sequence of octets containing 413 the output of the hash algorithm. The Digest field must not be 414 empty. Section 3 describes how to calculate the digest for a zone. 415 Section 4 describes how to use the digest to verify the contents of a 416 zone. 418 2.3. ZONEMD Presentation Format 420 The presentation format of the RDATA portion is as follows: 422 The Serial field is represented as an unsigned decimal integer. 424 The Scheme field is represented as an unsigned decimal integer. 426 The Hash Algorithm field is represented as an unsigned decimal 427 integer. 429 The Digest is represented as a sequence of case-insensitive 430 hexadecimal digits. Whitespace is allowed within the hexadecimal 431 text. 433 2.4. ZONEMD Example 435 The following example shows a ZONEMD RR. 437 example.com. 86400 IN ZONEMD 2018031500 1 1 ( 438 FEBE3D4CE2EC2FFA4BA99D46CD69D6D29711E55217057BEE 439 7EB1A7B641A47BA7FED2DD5B97AE499FAFA4F22C6BD647DE ) 441 3. Calculating the Digest 443 3.1. Add ZONEMD Placeholder 445 In preparation for calculating the zone digest, any existing ZONEMD 446 records (and covering RRSIGs) at the zone apex are first deleted. 448 Prior to calculation of the digest, and prior to signing with DNSSEC, 449 one or more placeholder ZONEMD records are added to the zone apex. 450 This ensures that denial-of-existence (NSEC, NSEC3) records are 451 created correctly if the zone is signed with DNSSEC. If placeholders 452 are not added prior to signing, the later addition of ZONEMD records 453 would also require updating the Type Bit Maps field of any apex NSEC/ 454 NSEC3 RRs, which then invalidates the calculated digest value. 456 When multiple ZONEMD RRs are published in the zone, e.g., during an 457 algorithm rollover, each must specify a unique Scheme and Hash 458 Algorithm tuple. 460 It is recommended that the TTL of the ZONEMD record match the TTL of 461 the SOA. 463 In the placeholder record, the Serial field is set to the current SOA 464 Serial. The Scheme field is set to the value for the chosen 465 collation scheme. The Hash Algorithm field is set to the value for 466 the chosen hash algorithm. Since ZONEMD records are excluded from 467 digest calculation, the value of the Digest field does not matter at 468 this point in the process. 470 3.2. Optionally Sign the Zone 472 Following addition of placeholder records, the zone may be signed 473 with DNSSEC. Note that when the digest calculation is complete, and 474 the ZONEMD record is updated, the signature(s) for the ZONEMD RRSet 475 MUST be recalculated and updated as well. Therefore, the signer is 476 not required to calculate a signature over the placeholder record at 477 this step in the process, but it is harmless to do so. 479 3.3. Scheme-Specific Processing 481 At this time, only the SIMPLE collation scheme is defined. 482 Additional schemes may be defined in future updates to this document. 484 3.3.1. The SIMPLE Scheme 486 For the SIMPLE scheme, the digest is calculated over the zone as a 487 whole. This means that a change to a single RR in the zone requires 488 iterating over all RRs in the zone to recalculate the digest. SIMPLE 489 is a good choice for zones that are small and/or stable, but probably 490 not good for zones that are large and/or dynamic. 492 Calculation of a zone digest REQUIRES RRs to be processed in a 493 consistent format and ordering. Correct ordering depends on (1) 494 ordering of owner names, (2) ordering of RRSets with the same owner 495 name, and (3) ordering of RRs within an RRSet. 497 3.3.1.1. SIMPLE Scheme RR Format 499 This specification adopts DNSSEC's canonical on-the-wire RR format 500 (without name compression) as specified in [RFC4034]: 502 RR(i) = owner | type | class | TTL | RDATA length | RDATA 504 where "|" denotes concatenation. 506 3.3.1.2. SIMPLE Scheme RR Ordering 508 This specification adopts DNSSEC's canonical ordering for names 509 (Section 6.1 of [RFC4034]), and canonical ordering for RRs within an 510 RRSet (Section 6.3 of [RFC4034]). It also adopts DNSSEC's canonical 511 RR form (Section 6.2 of [RFC4034]). 513 However, since DNSSEC does not define a canonical ordering for RRSets 514 having the same owner name, that ordering is defined here. For the 515 purposes of calculating the zone digest, RRSets having the same owner 516 name MUST be numerically ordered, in ascending order, by their 517 numeric RR TYPE. 519 3.3.1.3. SIMPLE Scheme Inclusion/Exclusion Rules 521 When iterating over records in the zone, the following inclusion/ 522 exclusion rules apply: 524 o All records in the zone, including glue records, MUST be included. 526 o Occluded data ([RFC5936] Section 3.5) MUST be included. 528 o If there are duplicate RRs with equal owner, class, type, and 529 RDATA, only one instance is included ([RFC4034] Section 6.3), and 530 the duplicates MUST be omitted. 532 o The placeholder ZONEMD RR(s) MUST NOT be included. 534 o If the zone is signed, DNSSEC RRs MUST be included, except: 536 o The RRSIG covering ZONEMD MUST NOT be included because the RRSIG 537 will be updated after all digests have been calculated. 539 3.3.1.4. 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 described in Section 3.3.1.1, in 543 the order described in Section 3.3.1.2, subject to the inclusion/ 544 exclusion rules described in Section 3.3.1.3, and then applying the 545 SHA-384 algorithm: 547 digest = SHA384( RR(1) | RR(2) | RR(3) | ... ) 549 where "|" denotes concatenation. 551 3.4. Update ZONEMD RR 553 Once a zone digest has been calculated, the published ZONEMD record 554 is finalised by inserting the digest into the placeholder ZONEMD. 555 Repeat for each digest if multiple digests are to be published. 557 If the zone is signed with DNSSEC, the RRSIG record(s) covering the 558 ZONEMD RRSet MUST then be added or updated. Because the ZONEMD 559 placeholder was added prior to signing, the zone will already have 560 the appropriate denial-of-existence (NSEC, NSEC3) records. 562 Some DNSSEC implementations (especially "online signing") might be 563 designed such that the SOA serial number is updated whenever a new 564 signature is made. To preserve the calculated digest, generation of 565 an ZONEMD signature must not also result in a change to the SOA 566 serial number. The ZONEMD RR and the matching SOA MUST be published 567 at the same time. 569 4. Verifying Zone Digest 571 The recipient of a zone that has a ZONEMD RR can verify the zone by 572 calculating the digest as follows. If multiple ZONEMD RRs are 573 present in the zone, e.g., during an algorithm rollover, a match 574 using any one of the recipient's supported Schemes and Hash 575 Algorithms is sufficient to verify the zone. 577 1. The verifier MUST first determine whether or not to expect DNSSEC 578 records in the zone. This can be done by examining locally 579 configured trust anchors, or querying for (and validating) DS RRs 580 in the parent zone. For zones that are provably insecure, or if 581 DNSSEC validation can not be performed, digest validation 582 continues at step 4 below. 584 2. For zones that are provably secure, the existence of the apex 585 ZONEMD record MUST be verified. If the ZONEMD record provably 586 does not exist, digest verification cannot be done. If the 587 ZONEMD record does provably exist, but is not found in the zone, 588 digest verification MUST NOT be considered successful. 590 3. For zones that are provably secure, the SOA and ZONEMD RRSets 591 MUST have valid signatures, chaining up to a trust anchor. If 592 DNSSEC validation of the SOA or ZONEMD records fails, digest 593 verification MUST NOT be considered successful. 595 4. When multiple ZONEMD RRs are present, each must specify a unique 596 Scheme and Hash Algorithm tuple. If the ZONEMD RRSet contains 597 more than one RR with the same Scheme and Hash Algorithm, digest 598 verification MUST NOT be considered successful. 600 5. Loop over all apex ZONEMD RRs and perform the following steps: 602 A. The SOA Serial field MUST exactly match the ZONEMD Serial 603 field. If the fields do not match, digest verification MUST 604 NOT be considered successful with this ZONEMD RR. 606 B. The Scheme field MUST be checked. If the verifier does not 607 support the given scheme, it SHOULD report that the RR's 608 digest could not be verified due to an unsupported scheme. 610 C. The Hash Algorithm field MUST be checked. If the verifier 611 does not support the given hash algorithm, it SHOULD report 612 that the RR's digest could not be verified due to an 613 unsupported algorithm. 615 D. The zone digest is computed over the zone data as described 616 in Section 3.3, using the Scheme and Hash Algorithm for the 617 current ZONEMD RR. 619 E. The computed digest is compared to the received digest. If 620 the two digest values match, verification is considered 621 successful. Otherwise, verification MUST NOT be considered 622 successful for this ZONEMD RR. 624 5. IANA Considerations 626 5.1. ZONEMD RRtype 628 This document defines a new DNS RR type, ZONEMD, whose value 63 has 629 been allocated by IANA from the "Resource Record (RR) TYPEs" 630 subregistry of the "Domain Name System (DNS) Parameters" registry: 632 Type: ZONEMD 634 Value: 63 636 Meaning: Message Digest Over Zone Data 638 Reference: This document 640 5.2. ZONEMD Scheme 642 This document asks IANA to create a new "ZONEMD Scheme" registry with 643 initial contents as follows: 645 +---------+--------------------+----------+-----------+-------------+ 646 | Value | Description | Mnemonic | Status | Reference | 647 +---------+--------------------+----------+-----------+-------------+ 648 | 0 | Reserved | RESERVED | N/A | N/A | 649 | 1 | Simple ZONEMD | SIMPLE | Mandatory | This | 650 | | collation | | | document | 651 | 240-254 | Private Use | N/A | N/A | [RFC8126] | 652 +---------+--------------------+----------+-----------+-------------+ 654 Table 1: ZONEMD Scheme Registry 656 The IANA policy for assigning new values to the ZONEMD Scheme 657 registry shall be Specification Required, as described in [RFC8126]. 659 5.3. ZONEMD Hash Algorithm 661 This document asks IANA to create a new "ZONEMD Hash Algorithm" 662 registry with initial contents as follows: 664 +---------+----------------------+----------+-----------+-----------+ 665 | Value | Description | Mnemonic | Status | Reference | 666 +---------+----------------------+----------+-----------+-----------+ 667 | 0 | Reserved | RESERVED | N/A | N/A | 668 | 1 | The SHA-384 hash | SHA384 | Mandatory | [RFC6234] | 669 | | algorithm | | | | 670 | 240-254 | Private Use | N/A | N/A | [RFC8126] | 671 +---------+----------------------+----------+-----------+-----------+ 673 Table 2: ZONEMD Hash Algorithm Registry 675 The IANA policy for assigning new values to the ZONEMD Hash Algorithm 676 registry shall be Specification Required, as described in [RFC8126]. 678 6. Security Considerations 680 6.1. Attacks Against the Zone Digest 682 The zone digest allows the receiver to verify that the zone contents 683 haven't been modified since the zone was generated/published. 684 Verification is strongest when the zone is also signed with DNSSEC. 685 An attacker, whose goal is to modify zone content before it is used 686 by the victim, may consider a number of different approaches. 688 The attacker might perform a downgrade attack to an unsigned zone. 689 This is why Section 4 talks about determining whether or not to 690 expect DNSSEC signatures for the zone in step 1. 692 The attacker might perform a downgrade attack by removing one or more 693 ZONEMD records. Such a removal is detectable only with DNSSEC 694 validation and is why Section 4 talks about checking denial-of- 695 existence proofs in step 2 and signature validation in step 3. 697 The attacker might alter the Scheme, Hash Algorithm, or Digest fields 698 of the ZONEMD record. Such modifications are detectable only with 699 DNSSEC validation. 701 6.2. Attacks Utilizing ZONEMD Queries 703 Nothing in this specification prevents clients from making, and 704 servers from responding to, ZONEMD queries. Servers SHOULD NOT 705 calculate zone digests dynamically (for each query) as this can be 706 used as a CPU resource exhaustion attack. 708 One might consider how well ZONEMD responses could be used in a 709 distributed denial-of-service amplification attack. The ZONEMD RR is 710 moderately sized, much like the DS RR. A single ZONEMD RR 711 contributes approximately 40 to 65 octets to a DNS response, for 712 currently defined digest types. Certainly other RR types, such as 713 DNSKEY, can result in larger amplification effects. 715 6.3. Resilience and Fragility 717 ZONEMD can be used to detect incomplete or corrupted zone data prior 718 to its use, thereby increasing resilience, but also introducing some 719 fragility. Publishers and consumers of zones containing ZONEMD 720 records should be aware of these tradeoffs. While the intention is 721 to secure the zone data, misconfigurations or implementation bugs are 722 generally indistinguishable from intentional tampering, and could 723 lead to service failures when verification is performed 724 automatically. 726 Zone publishers may want to deploy ZONEMD gradually, perhaps by 727 utilizing one of the private use hash algorithms listed in 728 Section 5.3. Similarly, recipients may want to initially configure 729 verification failures only as a warning, and later as an error after 730 gaining experience and confidence with the feature. 732 7. Performance Considerations 734 This section is provided to make zone publishers aware of the 735 performance requirements and implications of including ZONEMD RRs in 736 a zone. 738 7.1. SIMPLE SHA384 740 As mentioned previously, the SIMPLE scheme may not be appropriate for 741 use in zones that are either large or highly dynamic. Zone 742 publishers should carefully consider the use of ZONEMD in such zones, 743 since it might cause consumers of zone data (e.g., secondary name 744 servers) to expend resources on digest calculation. Furthermore, for 745 such use cases, it is recommended that ZONEMD only be used when 746 digest calculation time is significantly less than propagation times 747 and update intervals. 749 The authors' implementation (Section 10.1) includes an option to 750 record and report CPU usage of its operation. The software was used 751 to generate digests for more than 800 TLD zones available from 752 [CZDS]. The table below summarizes the the results for the SIMPLE 753 scheme and SHA384 hash algorithm grouped by zone size. The Rate 754 column is the mean amount of time per RR to calculate the digest, 755 running on commodity hardware at the time of this writing. 757 +---------------------+----------------+ 758 | Zone Size (RRs) | Rate (msec/RR) | 759 +---------------------+----------------+ 760 | 10 - 99 | 0.00683 | 761 | 100 - 999 | 0.00551 | 762 | 1000 - 9999 | 0.00505 | 763 | 10000 - 99999 | 0.00602 | 764 | 100000 - 999999 | 0.00845 | 765 | 1000000 - 9999999 | 0.0108 | 766 | 10000000 - 99999999 | 0.0148 | 767 +---------------------+----------------+ 769 For example, based on the above table, it takes approximately 0.13 770 seconds to calculate a SIMPLE SHA384 digest for a zone with 22,000 771 RRs, and about 2.5 seconds for a zone with 300,000 RRs. 773 These benchmarks attempt to emulate a worst-case scenario and take 774 into account the time required to canonicalize the zone for 775 processing. Each of the 800+ zones were measured three times, and 776 then averaged, with a different random sorting of the input data 777 prior to each measurement. 779 8. Privacy Considerations 781 This specification has no impact on user privacy. 783 9. Acknowledgments 785 The authors wish to thank David Blacka, Scott Hollenbeck, and Rick 786 Wilhelm for providing feedback on early drafts of this document. 787 Additionally, they thank Joe Abley, Mark Andrews, Ralph Dolmans, 788 Richard Gibson, Olafur Gudmundsson, Bob Harold, Paul Hoffman, Evan 789 Hunt, Shumon Huque, Tatuya Jinmei, Mike St. Johns, Burt Kaliski, 790 Shane Kerr, Matt Larson, John Levine, Ed Lewis, Matt Pounsett, Mukund 791 Sivaraman, Petr Spacek, Ondrej Sury, Willem Toorop, Florian Weimer, 792 Tim Wicinksi, Wouter Wijngarrds, Paul Wouters, and other members of 793 the dnsop working group for their input. 795 10. Implementation Status 797 10.1. Authors' Implementation 799 The authors have an open source implementation in C, using the ldns 800 library [ldns-zone-digest]. This implementation is able to perform 801 the following functions: 803 o Read an input zone and output a zone with the ZONEMD placeholder. 805 o Compute zone digest over signed zone and update the ZONEMD record. 807 o Re-compute DNSSEC signature over the ZONEMD record. 809 o Verify the zone digest from an input zone. 811 This implementation does not: 813 o Perform DNSSEC validation of the ZONEMD record during 814 verification. 816 10.2. Shane Kerr's Implementation 818 Shane Kerr wrote an implementation of this specification during the 819 IETF 102 hackathon [ZoneDigestHackathon]. This implementation is in 820 Python and is able to perform the following functions: 822 o Read an input zone and output a zone with ZONEMD record. 824 o Verify the zone digest from an input zone. 826 o Output the ZONEMD record in its defined presentation format. 828 This implementation does not: 830 o Re-compute DNSSEC signature over the ZONEMD record. 832 o Perform DNSSEC validation of the ZONEMD record. 834 10.3. NIC Chile Labs Implementation 836 NIC Chile Labs wrote an implementation of this specification as part 837 of "dns-tools" suite [DnsTools], which besides digesting, can also 838 sign and verify zones. This implementation is in Go and is able to 839 perform the following functions: 841 o Compute zone digest over signed zone and update the ZONEMD record. 843 o Verify the zone digest from an input zone. 845 o Perform DNSSEC validation of the ZONEMD record during 846 verification. 848 o Re-compute DNSSEC signature over the ZONEMD record. 850 11. Change Log 852 RFC Editor: Please remove this section. 854 This section lists substantial changes to the document as it is being 855 worked on. 857 From -00 to -01: 859 o Removed requirement to sort by RR CLASS. 861 o Added Kumari and Hardaker as coauthors. 863 o Added Change Log section. 865 o Minor clarifications and grammatical edits. 867 From -01 to -02: 869 o Emphasize desire for data security over channel security. 871 o Expanded motivation into its own subsection. 873 o Removed discussion topic whether or not to include serial in 874 ZONEMD. 876 o Clarified that a zone's NS records always sort before the SOA 877 record. 879 o Clarified that all records in the zone must are digested, except 880 as specified in the exclusion rules. 882 o Added for discussion out-of-zone and occluded records. 884 o Clarified that update of ZONEMD signature must not cause a serial 885 number change. 887 o Added persons to acknowledgments. 889 From -02 to -03: 891 o Added recommendation to set ZONEMD TTL to SOA TTL. 893 o Clarified that digest input uses uncompressed names. 895 o Updated Implementations section. 897 o Changed intended status from Standards Track to Experimental and 898 added Scope of Experiment section. 900 o Updated Motivation, Introduction, and Design Overview sections in 901 response to working group discussion. 903 o Gave ZONEMD digest types their own status, separate from DS digest 904 types. Request IANA to create a registry. 906 o Added Reserved field for future work supporting dynamic updates. 908 o Be more rigorous about having just ONE ZONEMD record in the zone. 910 o Expanded use cases. 912 From -03 to -04: 914 o Added an appendix with example zones and digests. 916 o Clarified that only apex ZONEMD RRs shall be processed. 918 From -04 to -05: 920 o Made SHA384 the only supported ZONEMD digest type. 922 o Disassociated ZONEMD digest types from DS digest types. 924 o Updates to Introduction based on list feedback. 926 o Changed "zone file" to "zone" everywhere. 928 o Restored text about why ZONEMD has a Serial field. 930 o Clarified ordering of RRSets having same owner to be numerically 931 ascending. 933 o Clarified that all duplicate RRs (not just SOA) must be suppressed 934 in digest calculation. 936 o Clarified that the Reserved field must be set to zero and checked 937 for zero in verification. 939 o Clarified that occluded data must be included. 941 o Clarified procedure for verification, using temporary location for 942 received digest. 944 o Explained why Reserved field is 8-bits. 946 o IANA Considerations section now more specific. 948 o Added complex zone to examples. 950 o 952 From -05 to -06: 954 o RR type code 63 was assigned to ZONEMD by IANA. 956 From -06 to -07: 958 o Fixed mistakes in ZONEMD examples. 960 o Added private use Digest Type values 240-254. 962 o Clarified that Digest field must not be empty. 964 From -07 to draft-ietf-dnsop-dns-zone-digest-00: 966 o Adopted by dnsop. 968 o Clarified further that non-apex ZONEMD RRs have no meaning. 970 o Changed "provably [un]signed" to "provably [in]secure". 972 o Allow multiple ZONEMD RRs to support algorithm agility/rollovers. 974 o Describe verification when there are multiple ZONEMD RRs. 976 From -00 to -01: 978 o Simplified requirements around verifying multiple digests. Any 979 one match is sufficient. 981 o Updated implementation notes. 983 o Both implementations produce expected results on examples given in 984 this document. 986 From -01 to -02: 988 o Changed the name of the Reserved field to Parameter. 990 o Changed the name of Digest Type 1 from SHA384 to SHA384-STABLE. 992 o The meaning of the Parameter field now depends on Digest Type. 994 o No longer require Parameter field to be zero in verification. 996 o Updated a rule from earlier versions that said multiple ZONEMD RRs 997 were not allowed. 999 From -02 to -03: 1001 o Changed the name of Digest Type 1 from SHA384-STABLE to 1002 SHA384-SIMPLE. 1004 o Changed document status from Experimental to Standards Track. 1006 o Removed Scope of Experimentation section. 1008 From -03 to -04: 1010 o Addressing WGLC feedback. 1012 o Changed from "Digest Type + Paramter" to "Scheme + Hash 1013 Algorithm". This should make it more obvious how ZONEMD can be 1014 expanded in the future with new schemes and hash algorithms, while 1015 sacrificing some of the flexibility that the Parameter was 1016 intended to provide. 1018 o Note: old RDATA fields: Serial, Digest Type, Parameter, Digest. 1020 o Note: new RDATA fields: Serial, Scheme, Hash Algorithm, Digest. 1022 o Add new IANA requirement for a Scheme registry. 1024 o Rearranged some sections and separated scheme-specific aspects 1025 from general aspects of digest calculation. 1027 o When discussing multiple ZONEMD RRs, allow for Scheme, as well as 1028 Hash Algorithm, transition. 1030 o Added Performance Considerations section with some benchmarks. 1032 o Further clarifications about non-apex ZONEMD RRs. 1034 o Clarified inclusion rule for duplicate RRs. 1036 o Removed or lowercased some inappropriately used RFC 2119 key 1037 words. 1039 o Clarified that all ZONEMD RRs, even for unsupported hash 1040 algorithms, must be zeroized during digest calculation. 1042 o Added Resilience and Fragility to security considerations. 1044 o Updated examples since changes in this version result in different 1045 hash values. 1047 From -04 to -05: 1049 o Clarifications about non-apex and multiple ZONEMD RRs. 1051 o Clarifications about benchmark results. 1053 o Don't compute ZONEMD on-the-fly. 1055 o Specifciation Required for updates to ZONEMD protocol registries. 1057 o Other rewording based on WGLC feedback. 1059 o Updated RFC numbers for some references. 1061 o Use documentation IP addresses instead of loopback. 1063 o Updated examples in the appendix. 1065 From -05 to -06: 1067 o Per WG suggestion, no longer include any apex ZONEMD record in 1068 digest calculation. 1070 o Updated examples in the appendix. 1072 o Clarified verification procedure by describing a loop over all 1073 ZONEMD RRs. 1075 From -06 to -07: 1077 o Added NIC Chile Labs implementation. 1079 From -07 to -08: 1081 o Update an author's affiliation. 1083 o Clarified why placeholder RRs are still important (for NSEC/ 1084 NSEC3). 1086 o Moved subsection ("Order of RRSets Having the Same Owner Name") 1087 with single sentence paragraph up into parent section. 1089 From -08 to -09: 1091 o Moved format, ordering, inclusion/exclusion into a sub section 1092 specific to the SIMPLE scheme. 1094 o Further clarified rules about multiple ZONEMD RRs (AD comments). 1096 o Reworeded rules about processing of duplicate zone RRs (AD 1097 comments). 1099 o Removed sentence about optional zeroing of digest prior to 1100 calculation (AD comments). 1102 o Other minor changes (AD comments). 1104 12. References 1106 12.1. Normative References 1108 [RFC1034] Mockapetris, P., "Domain names - concepts and facilities", 1109 STD 13, RFC 1034, DOI 10.17487/RFC1034, November 1987, 1110 . 1112 [RFC1035] Mockapetris, P., "Domain names - implementation and 1113 specification", STD 13, RFC 1035, DOI 10.17487/RFC1035, 1114 November 1987, . 1116 [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate 1117 Requirement Levels", BCP 14, RFC 2119, 1118 DOI 10.17487/RFC2119, March 1997, 1119 . 1121 [RFC4034] Arends, R., Austein, R., Larson, M., Massey, D., and S. 1122 Rose, "Resource Records for the DNS Security Extensions", 1123 RFC 4034, DOI 10.17487/RFC4034, March 2005, 1124 . 1126 [RFC6234] Eastlake 3rd, D. and T. Hansen, "US Secure Hash Algorithms 1127 (SHA and SHA-based HMAC and HKDF)", RFC 6234, 1128 DOI 10.17487/RFC6234, May 2011, 1129 . 1131 [RFC8174] Leiba, B., "Ambiguity of Uppercase vs Lowercase in RFC 1132 2119 Key Words", BCP 14, RFC 8174, DOI 10.17487/RFC8174, 1133 May 2017, . 1135 12.2. Informative References 1137 [CZDS] Internet Corporation for Assigned Names and Numbers, 1138 "Centralized Zone Data Service", October 2018, 1139 . 1141 [DnsTools] 1142 NIC Chile Labs, "DNS tools for zone signature (file, 1143 pkcs11-hsm) and validation, and zone digest (ZONEMD)", 1144 April 2020, . 1146 [InterNIC] 1147 ICANN, "InterNIC FTP site", May 2018, 1148 . 1150 [ldns-zone-digest] 1151 Verisign, "Implementation of Message Digests for DNS Zones 1152 using the ldns library", July 2018, 1153 . 1155 [RFC1995] Ohta, M., "Incremental Zone Transfer in DNS", RFC 1995, 1156 DOI 10.17487/RFC1995, August 1996, 1157 . 1159 [RFC2065] Eastlake 3rd, D. and C. Kaufman, "Domain Name System 1160 Security Extensions", RFC 2065, DOI 10.17487/RFC2065, 1161 January 1997, . 1163 [RFC2136] Vixie, P., Ed., Thomson, S., Rekhter, Y., and J. Bound, 1164 "Dynamic Updates in the Domain Name System (DNS UPDATE)", 1165 RFC 2136, DOI 10.17487/RFC2136, April 1997, 1166 . 1168 [RFC2535] Eastlake 3rd, D., "Domain Name System Security 1169 Extensions", RFC 2535, DOI 10.17487/RFC2535, March 1999, 1170 . 1172 [RFC2845] Vixie, P., Gudmundsson, O., Eastlake 3rd, D., and B. 1173 Wellington, "Secret Key Transaction Authentication for DNS 1174 (TSIG)", RFC 2845, DOI 10.17487/RFC2845, May 2000, 1175 . 1177 [RFC2931] Eastlake 3rd, D., "DNS Request and Transaction Signatures 1178 ( SIG(0)s )", RFC 2931, DOI 10.17487/RFC2931, September 1179 2000, . 1181 [RFC4880] Callas, J., Donnerhacke, L., Finney, H., Shaw, D., and R. 1182 Thayer, "OpenPGP Message Format", RFC 4880, 1183 DOI 10.17487/RFC4880, November 2007, 1184 . 1186 [RFC5751] Ramsdell, B. and S. Turner, "Secure/Multipurpose Internet 1187 Mail Extensions (S/MIME) Version 3.2 Message 1188 Specification", RFC 5751, DOI 10.17487/RFC5751, January 1189 2010, . 1191 [RFC5936] Lewis, E. and A. Hoenes, Ed., "DNS Zone Transfer Protocol 1192 (AXFR)", RFC 5936, DOI 10.17487/RFC5936, June 2010, 1193 . 1195 [RFC7696] Housley, R., "Guidelines for Cryptographic Algorithm 1196 Agility and Selecting Mandatory-to-Implement Algorithms", 1197 BCP 201, RFC 7696, DOI 10.17487/RFC7696, November 2015, 1198 . 1200 [RFC7858] Hu, Z., Zhu, L., Heidemann, J., Mankin, A., Wessels, D., 1201 and P. Hoffman, "Specification for DNS over Transport 1202 Layer Security (TLS)", RFC 7858, DOI 10.17487/RFC7858, May 1203 2016, . 1205 [RFC8126] Cotton, M., Leiba, B., and T. Narten, "Guidelines for 1206 Writing an IANA Considerations Section in RFCs", BCP 26, 1207 RFC 8126, DOI 10.17487/RFC8126, June 2017, 1208 . 1210 [RFC8484] Hoffman, P. and P. McManus, "DNS Queries over HTTPS 1211 (DoH)", RFC 8484, DOI 10.17487/RFC8484, October 2018, 1212 . 1214 [RFC8499] Hoffman, P., Sullivan, A., and K. Fujiwara, "DNS 1215 Terminology", BCP 219, RFC 8499, DOI 10.17487/RFC8499, 1216 January 2019, . 1218 [RFC8806] Kumari, W. and P. Hoffman, "Running a Root Server Local to 1219 a Resolver", RFC 8806, DOI 10.17487/RFC8806, June 2020, 1220 . 1222 [RootServers] 1223 Root Server Operators, "Root Server Technical Operations", 1224 July 2018, . 1226 [RPZ] Vixie, P. and V. Schryver, "DNS Response Policy Zones 1227 (RPZ)", draft-vixie-dnsop-dns-rpz-00 (work in progress), 1228 June 2018, . 1231 [ZoneDigestHackathon] 1232 Kerr, S., "Prototype implementation of ZONEMD for the IETF 1233 102 hackathon in Python", July 2018, 1234 . 1236 Appendix A. Example Zones With Digests 1238 This appendix contains example zones with accurate ZONEMD records. 1239 These can be used to verify an implementation of the zone digest 1240 protocol. 1242 A.1. Simple EXAMPLE Zone 1244 Here, the EXAMPLE zone contains an SOA record, NS and glue records, 1245 and a ZONEMD record. 1247 example. 86400 IN SOA ns1 admin 2018031900 ( 1248 1800 900 604800 86400 ) 1249 86400 IN NS ns1 1250 86400 IN NS ns2 1251 86400 IN ZONEMD 2018031900 1 1 ( 1252 c68090d90a7aed71 1253 6bc459f9340e3d7c 1254 1370d4d24b7e2fc3 1255 a1ddc0b9a87153b9 1256 a9713b3c9ae5cc27 1257 777f98b8e730044c ) 1258 ns1 3600 IN A 203.0.113.63 1259 ns2 3600 IN AAAA 2001:db8::63 1261 A.2. Complex EXAMPLE Zone 1263 Here, the EXAMPLE zone contains duplicate RRs, and an occluded RR, 1264 and one out-of-zone RR. 1266 example. 86400 IN SOA ns1 admin 2018031900 ( 1267 1800 900 604800 86400 ) 1268 86400 IN NS ns1 1269 86400 IN NS ns2 1270 86400 IN ZONEMD 2018031900 1 1 ( 1271 31cefb03814f5062 1272 ad12fa951ba0ef5f 1273 8da6ae354a415767 1274 246f7dc932ceb1e7 1275 42a2108f529db6a3 1276 3a11c01493de358d ) 1277 ns1 3600 IN A 203.0.113.63 1278 ns2 3600 IN AAAA 2001:db8::63 1279 occluded.sub 7200 IN TXT "I'm occluded but must be digested" 1280 sub 7200 IN NS ns1 1281 duplicate 300 IN TXT "I must be digested just once" 1282 duplicate 300 IN TXT "I must be digested just once" 1283 foo.test. 555 IN TXT "out-of-zone data must be excluded" 1284 non-apex 900 IN ZONEMD 2018031900 1 1 ( 1285 616c6c6f77656420 1286 6275742069676e6f 1287 7265642e20616c6c 1288 6f77656420627574 1289 2069676e6f726564 1290 2e20616c6c6f7765 ) 1292 A.3. EXAMPLE Zone with multiple digests 1294 Here, the EXAMPLE zone contains multiple ZONEMD records. Since only 1295 one Scheme (SIMPLE) and one Hash Algorithm (SHA384) is defined at 1296 this time, this example utilizes additional ZONEMD records with 1297 Scheme and Hash Algorithm values in the private range (240-254). 1298 These additional private-range digests are not verifiable. 1300 example. 86400 IN SOA ns1 admin 2018031900 ( 1301 1800 900 604800 86400 ) 1302 example. 86400 IN NS ns1.example. 1303 example. 86400 IN NS ns2.example. 1304 example. 86400 IN ZONEMD 2018031900 1 1 ( 1305 62e6cf51b02e54b9 1306 b5f967d547ce4313 1307 6792901f9f88e637 1308 493daaf401c92c27 1309 9dd10f0edb1c56f8 1310 080211f8480ee306 ) 1311 example. 86400 IN ZONEMD 2018031900 1 240 ( 1312 e2d523f654b9422a 1313 96c5a8f44607bbee ) 1314 example. 86400 IN ZONEMD 2018031900 241 1 ( 1315 e1846540e33a9e41 1316 89792d18d5d131f6 1317 05fc283e ) 1318 ns1.example. 3600 IN A 203.0.113.63 1319 ns2.example. 86400 IN TXT "This example has multiple digests" 1320 ns2.example. 3600 IN AAAA 2001:db8::63 1322 A.4. The URI.ARPA Zone 1324 The URI.ARPA zone retrieved 2018-10-21. Note this sample zone has 1325 (expired) signatures, but no signature for the ZONEMD RR. 1327 ; <<>> DiG 9.9.4 <<>> @lax.xfr.dns.icann.org uri.arpa axfr 1328 ; (2 servers found) 1329 ;; global options: +cmd 1330 uri.arpa. 3600 IN SOA sns.dns.icann.org. ( 1331 noc.dns.icann.org. 2018100702 10800 3600 1209600 3600 ) 1332 uri.arpa. 3600 IN RRSIG NSEC 8 2 3600 ( 1333 20181028142623 20181007205525 47155 uri.arpa. 1334 eEC4w/oXLR1Epwgv4MBiDtSBsXhqrJVvJWUpbX8XpetAvD35bxwNCUTi 1335 /pAJVUXefegWeiriD2rkTgCBCMmn7YQIm3gdR+HjY/+o3BXNQnz97f+e 1336 HAE9EDDzoNVfL1PyV/2fde9tDeUuAGVVwmD399NGq9jWYMRpyri2kysr q/g= ) 1337 uri.arpa. 86400 IN RRSIG NS 8 2 86400 ( 1338 20181028172020 20181007175821 47155 uri.arpa. 1339 ATyV2A2A8ZoggC+68u4GuP5MOUuR+2rr3eWOkEU55zAHld/7FiBxl4ln 1340 4byJYy7NudUwlMOEXajqFZE7DVl8PpcvrP3HeeGaVzKqaWj+aus0jbKF 1341 Bsvs2b1qDZemBfkz/IfAhUTJKnto0vSUicJKfItu0GjyYNJCz2CqEuGD Wxc= ) 1342 uri.arpa. 600 IN RRSIG MX 8 2 600 ( 1343 20181028170556 20181007175821 47155 uri.arpa. 1344 e7/r3KXDohX1lyVavetFFObp8fB8aXT76HnN9KCQDxSnSghNM83UQV0t 1345 lTtD8JVeN1mCvcNFZpagwIgB7XhTtm6Beur/m5ES+4uSnVeS6Q66HBZK 1346 A3mR95IpevuVIZvvJ+GcCAQpBo6KRODYvJ/c/ZG6sfYWkZ7qg/Em5/+3 4UI= ) 1347 uri.arpa. 3600 IN RRSIG DNSKEY 8 2 3600 ( 1348 20181028152832 20181007175821 15796 uri.arpa. 1349 nzpbnh0OqsgBBP8St28pLvPEQ3wZAUdEBuUwil+rtjjWlYYiqjPxZ286 1350 XF4Rq1usfV5x71jZz5IqswOaQgia91ylodFpLuXD6FTGs2nXGhNKkg1V 1351 chHgtwj70mXU72GefVgo8TxrFYzxuEFP5ZTP92t97FVWVVyyFd86sbbR 1352 6DZj3uA2wEvqBVLECgJLrMQ9Yy7MueJl3UA4h4E6zO2JY9Yp0W9woq0B 1353 dqkkwYTwzogyYffPmGAJG91RJ2h6cHtFjEZe2MnaY2glqniZ0WT9vXXd 1354 uFPm0KD9U77Ac+ZtctAF9tsZwSdAoL365E2L1usZbA+K0BnPPqGFJRJk 1355 5R0A1w== ) 1356 uri.arpa. 3600 IN RRSIG DNSKEY 8 2 3600 ( 1357 20181028152832 20181007175821 55480 uri.arpa. 1358 lWtQV/5szQjkXmbcD47/+rOW8kJPksRFHlzxxmzt906+DBYyfrH6uq5X 1359 nHvrUlQO6M12uhqDeL+bDFVgqSpNy+42/OaZvaK3J8EzPZVBHPJykKMV 1360 63T83aAiJrAyHzOaEdmzLCpalqcEE2ImzlLHSafManRfJL8Yuv+JDZFj 1361 2WDWfEcUuwkmIZWX11zxp+DxwzyUlRl7x4+ok5iKZWIg5UnBAf6B8T75 1362 WnXzlhCw3F2pXI0a5LYg71L3Tp/xhjN6Yy9jGlIRf5BjB59X2zra3a2R 1363 PkI09SSnuEwHyF1mDaV5BmQrLGRnCjvwXA7ho2m+vv4SP5dUdXf+GTeA 1364 1HeBfw== ) 1365 uri.arpa. 3600 IN RRSIG SOA 8 2 3600 ( 1366 20181029114753 20181008222815 47155 uri.arpa. 1367 qn8yBNoHDjGdT79U2Wu9IIahoS0YPOgYP8lG+qwPcrZ1BwGiHywuoUa2 1368 Mx6BWZlg+HDyaxj2iOmox+IIqoUHhXUbO7IUkJFlgrOKCgAR2twDHrXu 1369 9BUQHy9SoV16wYm3kBTEPyxW5FFm8vcdnKAF7sxSY8BbaYNpRIEjDx4A JUc= ) 1370 uri.arpa. 3600 IN NSEC ftp.uri.arpa. NS SOA ( 1371 MX RRSIG NSEC DNSKEY ) 1372 uri.arpa. 86400 IN NS a.iana-servers.net. 1373 uri.arpa. 86400 IN NS b.iana-servers.net. 1374 uri.arpa. 86400 IN NS c.iana-servers.net. 1375 uri.arpa. 86400 IN NS ns2.lacnic.net. 1376 uri.arpa. 86400 IN NS sec3.apnic.net. 1377 uri.arpa. 600 IN MX 10 pechora.icann.org. 1378 uri.arpa. 3600 IN DNSKEY 256 3 8 ( 1379 AwEAAcBi7tSart2J599zbYWspMNGN70IBWb4ziqyQYH9MTB/VCz6WyUK 1380 uXunwiJJbbQ3bcLqTLWEw134B6cTMHrZpjTAb5WAwg4XcWUu8mdcPTiL 1381 Bl6qVRlRD0WiFCTzuYUfkwsh1Rbr7rvrxSQhF5rh71zSpwV5jjjp65Wx 1382 SdJjlH0B ) 1383 uri.arpa. 3600 IN DNSKEY 257 3 8 ( 1384 AwEAAbNVv6ulgRdO31MtAehz7j3ALRjwZglWesnzvllQl/+hBRZr9QoY 1385 cO2I+DkO4Q1NKxox4DUIxj8SxPO3GwDuOFR9q2/CFi2O0mZjafbdYtWc 1386 3zSdBbi3q0cwCIx7GuG9eqlL+pg7mdk9dgdNZfHwB0LnqTD8ebLPsrO/ 1387 Id7kBaiqYOfMlZnh2fp+2h6OOJZHtY0DK1UlssyB5PKsE0tVzo5s6zo9 1388 iXKe5u+8WTMaGDY49vG80JPAKE7ezMiH/NZcUMiE0PRZ8D3foq2dYuS5 1389 ym+vA83Z7v8A+Rwh4UGnjxKB8zmr803V0ASAmHz/gwH5Vb0nH+LObwFt 1390 l3wpbp+Wpm8= ) 1391 uri.arpa. 3600 IN DNSKEY 257 3 8 ( 1392 AwEAAbwnFTakCvaUKsXji4mgmxZUJi1IygbnGahbkmFEa0L16J+TchKR 1393 wcgzVfsxUGa2MmeA4hgkAooC3uy+tTmoMsgy8uq/JAj24DjiHzd46LfD 1394 FK/qMidVqFpYSHeq2Vv5ojkuIsx4oe4KsafGWYNOczKZgH5loGjN2aJG 1395 mrIm++XCphOskgCsQYl65MIzuXffzJyxlAuts+ecAIiVeqRaqQfr8LRU 1396 7wIsLxinXirprtQrbor+EtvlHp9qXE6ARTZDzf4jvsNpKvLFZtmxzFf3 1397 e/UJz5eHjpwDSiZL7xE8aE1o1nGfPtJx9ZnB3bapltaJ5wY+5XOCKgY0 1398 xmJVvNQlwdE= ) 1399 ftp.uri.arpa. 3600 IN RRSIG NSEC 8 3 3600 ( 1400 20181028080856 20181007175821 47155 uri.arpa. 1401 HClGAqPxzkYkAT7Q/QNtQeB6YrkP6EPOef+9Qo5/2zngwAewXEAQiyF9 1402 jD1USJiroM11QqBS3v3aIdW/LXORs4Ez3hLcKNO1cKHsOuWAqzmE+BPP 1403 Arfh8N95jqh/q6vpaB9UtMkQ53tM2fYU1GszOLN0knxbHgDHAh2axMGH lqM= ) 1404 ftp.uri.arpa. 604800 IN RRSIG NAPTR 8 3 604800 ( 1405 20181028103644 20181007205525 47155 uri.arpa. 1406 WoLi+vZzkxaoLr2IGZnwkRvcDf6KxiWQd1WZP/U+AWnV+7MiqsWPZaf0 1407 9toRErerGoFOiOASNxZjBGJrRgjmavOM9U+LZSconP9zrNFd4dIu6kp5 1408 YxlQJ0uHOvx1ZHFCj6lAt1ACUIw04ZhMydTmi27c8MzEOMepvn7iH7r7 k7k= ) 1409 ftp.uri.arpa. 3600 IN NSEC http.uri.arpa. NAPTR ( 1410 RRSIG NSEC ) 1411 ftp.uri.arpa. 604800 IN NAPTR 0 0 "" "" ( 1412 "!^ftp://([^:/?#]*).*$!\\1!i" . ) 1413 http.uri.arpa. 3600 IN RRSIG NSEC 8 3 3600 ( 1414 20181029010647 20181007175821 47155 uri.arpa. 1415 U03NntQ73LHWpfLmUK8nMsqkwVsOGW2KdsyuHYAjqQSZvKbtmbv7HBmE 1416 H1+Ii3Z+wtfdMZBy5aC/6sHdx69BfZJs16xumycMlAy6325DKTQbIMN+ 1417 ift9GrKBC7cgCd2msF/uzSrYxxg4MJQzBPvlkwXnY3b7eJSlIXisBIn7 3b8= ) 1418 http.uri.arpa. 604800 IN RRSIG NAPTR 8 3 604800 ( 1419 20181029011815 20181007205525 47155 uri.arpa. 1420 T7mRrdag+WSmG+n22mtBSQ/0Y3v+rdDnfQV90LN5Fq32N5K2iYFajF7F 1421 Tp56oOznytfcL4fHrqOE0wRc9NWOCCUec9C7Wa1gJQcllEvgoAM+L6f0 1422 RsEjWq6+9jvlLKMXQv0xQuMX17338uoD/xiAFQSnDbiQKxwWMqVAimv5 7Zs= ) 1423 http.uri.arpa. 3600 IN NSEC mailto.uri.arpa. NAPTR ( 1424 RRSIG NSEC ) 1425 http.uri.arpa. 604800 IN NAPTR 0 0 "" "" ( 1426 "!^http://([^:/?#]*).*$!\\1!i" . ) 1427 mailto.uri.arpa. 3600 IN RRSIG NSEC 8 3 3600 ( 1428 20181028110727 20181007175821 47155 uri.arpa. 1429 GvxzVL85rEukwGqtuLxek9ipwjBMfTOFIEyJ7afC8HxVMs6mfFa/nEM/ 1430 IdFvvFg+lcYoJSQYuSAVYFl3xPbgrxVSLK125QutCFMdC/YjuZEnq5cl 1431 fQciMRD7R3+znZfm8d8u/snLV9w4D+lTBZrJJUBe1Efc8vum5vvV7819 ZoY= ) 1432 mailto.uri.arpa. 604800 IN RRSIG NAPTR 8 3 604800 ( 1433 20181028141825 20181007205525 47155 uri.arpa. 1434 MaADUgc3fc5v++M0YmqjGk3jBdfIA5RuP62hUSlPsFZO4k37erjIGCfF 1435 j+g84yc+QgbSde0PQHszl9fE/+SU5ZXiS9YdcbzSZxp2erFpZOTchrpg 1436 916T4vx6i59scodjb0l6bDyZ+mtIPrc1w6b4hUyOUTsDQoAJYxdfEuMg Vy4= ) 1437 mailto.uri.arpa. 3600 IN NSEC urn.uri.arpa. NAPTR ( 1438 RRSIG NSEC ) 1439 mailto.uri.arpa. 604800 IN NAPTR 0 0 "" "" ( 1440 "!^mailto:(.*)@(.*)$!\\2!i" . ) 1441 urn.uri.arpa. 3600 IN RRSIG NSEC 8 3 3600 ( 1442 20181028123243 20181007175821 47155 uri.arpa. 1443 Hgsw4Deops1O8uWyELGe6hpR/OEqCnTHvahlwiQkHhO5CSEQrbhmFAWe 1444 UOkmGAdTEYrSz+skLRQuITRMwzyFf4oUkZihGyhZyzHbcxWfuDc/Pd/9 1445 DSl56gdeBwy1evn5wBTms8yWQVkNtphbJH395gRqZuaJs3LD/qTyJ5Dp LvA= ) 1446 urn.uri.arpa. 604800 IN RRSIG NAPTR 8 3 604800 ( 1447 20181029071816 20181007205525 47155 uri.arpa. 1448 ALIZD0vBqAQQt40GQ0Efaj8OCyE9xSRJRdyvyn/H/wZVXFRFKrQYrLAS 1449 D/K7q6CMTOxTRCu2J8yes63WJiaJEdnh+dscXzZkmOg4n5PsgZbkvUSW 1450 BiGtxvz5jNncM0xVbkjbtByrvJQAO1cU1mnlDKe1FmVB1uLpVdA9Ib4J hMU= ) 1451 urn.uri.arpa. 3600 IN NSEC uri.arpa. NAPTR RRSIG ( 1452 NSEC ) 1453 urn.uri.arpa. 604800 IN NAPTR 0 0 "" "" ( 1454 "/urn:([^:]+)/\\1/i" . ) 1455 uri.arpa. 3600 IN SOA sns.dns.icann.org. ( 1456 noc.dns.icann.org. 2018100702 10800 3600 1209600 3600 ) 1457 ;; Query time: 66 msec 1458 ;; SERVER: 192.0.32.132#53(192.0.32.132) 1459 ;; WHEN: Sun Oct 21 20:39:28 UTC 2018 1460 ;; XFR size: 34 records (messages 1, bytes 3941) 1461 uri.arpa. 3600 IN ZONEMD 2018100702 1 1 ( 1462 1291b78ddf7669b1a39d014d87626b709b55774c5d7d58fa 1463 dc556439889a10eaf6f11d615900a4f996bd46279514e473 ) 1465 A.5. The ROOT-SERVERS.NET Zone 1467 The ROOT-SERVERS.NET zone retreived 2018-10-21. 1469 root-servers.net. 3600000 IN SOA a.root-servers.net. ( 1470 nstld.verisign-grs.com. 2018091100 14400 7200 1209600 3600000 ) 1471 root-servers.net. 3600000 IN NS a.root-servers.net. 1472 root-servers.net. 3600000 IN NS b.root-servers.net. 1473 root-servers.net. 3600000 IN NS c.root-servers.net. 1474 root-servers.net. 3600000 IN NS d.root-servers.net. 1475 root-servers.net. 3600000 IN NS e.root-servers.net. 1476 root-servers.net. 3600000 IN NS f.root-servers.net. 1477 root-servers.net. 3600000 IN NS g.root-servers.net. 1478 root-servers.net. 3600000 IN NS h.root-servers.net. 1479 root-servers.net. 3600000 IN NS i.root-servers.net. 1480 root-servers.net. 3600000 IN NS j.root-servers.net. 1481 root-servers.net. 3600000 IN NS k.root-servers.net. 1482 root-servers.net. 3600000 IN NS l.root-servers.net. 1483 root-servers.net. 3600000 IN NS m.root-servers.net. 1484 a.root-servers.net. 3600000 IN AAAA 2001:503:ba3e::2:30 1485 a.root-servers.net. 3600000 IN A 198.41.0.4 1486 b.root-servers.net. 3600000 IN MX 20 mail.isi.edu. 1487 b.root-servers.net. 3600000 IN AAAA 2001:500:200::b 1488 b.root-servers.net. 3600000 IN A 199.9.14.201 1489 c.root-servers.net. 3600000 IN AAAA 2001:500:2::c 1490 c.root-servers.net. 3600000 IN A 192.33.4.12 1491 d.root-servers.net. 3600000 IN AAAA 2001:500:2d::d 1492 d.root-servers.net. 3600000 IN A 199.7.91.13 1493 e.root-servers.net. 3600000 IN AAAA 2001:500:a8::e 1494 e.root-servers.net. 3600000 IN A 192.203.230.10 1495 f.root-servers.net. 3600000 IN AAAA 2001:500:2f::f 1496 f.root-servers.net. 3600000 IN A 192.5.5.241 1497 g.root-servers.net. 3600000 IN AAAA 2001:500:12::d0d 1498 g.root-servers.net. 3600000 IN A 192.112.36.4 1499 h.root-servers.net. 3600000 IN AAAA 2001:500:1::53 1500 h.root-servers.net. 3600000 IN A 198.97.190.53 1501 i.root-servers.net. 3600000 IN MX 10 mx.i.root-servers.org. 1502 i.root-servers.net. 3600000 IN AAAA 2001:7fe::53 1503 i.root-servers.net. 3600000 IN A 192.36.148.17 1504 j.root-servers.net. 3600000 IN AAAA 2001:503:c27::2:30 1505 j.root-servers.net. 3600000 IN A 192.58.128.30 1506 k.root-servers.net. 3600000 IN AAAA 2001:7fd::1 1507 k.root-servers.net. 3600000 IN A 193.0.14.129 1508 l.root-servers.net. 3600000 IN AAAA 2001:500:9f::42 1509 l.root-servers.net. 3600000 IN A 199.7.83.42 1510 m.root-servers.net. 3600000 IN AAAA 2001:dc3::35 1511 m.root-servers.net. 3600000 IN A 202.12.27.33 1512 root-servers.net. 3600000 IN SOA a.root-servers.net. ( 1513 nstld.verisign-grs.com. 2018091100 14400 7200 1209600 3600000 ) 1514 root-servers.net. 3600000 IN ZONEMD 2018091100 1 1 ( 1515 f1ca0ccd91bd5573d9f431c00ee0101b2545c97602be0a97 1516 8a3b11dbfc1c776d5b3e86ae3d973d6b5349ba7f04340f79 ) 1518 Authors' Addresses 1520 Duane Wessels 1521 Verisign 1522 12061 Bluemont Way 1523 Reston, VA 20190 1525 Phone: +1 703 948-3200 1526 Email: dwessels@verisign.com 1527 URI: http://verisign.com 1529 Piet Barber 1530 Verisign 1531 12061 Bluemont Way 1532 Reston, VA 20190 1534 Phone: +1 703 948-3200 1535 Email: pbarber@verisign.com 1536 URI: http://verisign.com 1538 Matt Weinberg 1539 Amazon 1541 Email: matweinb@amazon.com 1542 URI: http://amazon.com 1544 Warren Kumari 1545 Google 1546 1600 Amphitheatre Parkway 1547 Mountain View, CA 94043 1549 Email: warren@kumari.net 1551 Wes Hardaker 1552 USC/ISI 1553 P.O. Box 382 1554 Davis, CA 95617 1556 Email: ietf@hardakers.net