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Checking references for intended status: Informational ---------------------------------------------------------------------------- ** Obsolete normative reference: RFC 5785 (Obsoleted by RFC 8615) Summary: 1 error (**), 0 flaws (~~), 1 warning (==), 1 comment (--). Run idnits with the --verbose option for more detailed information about the items above. -------------------------------------------------------------------------------- 2 Network Working Group W. Koch 3 Internet-Draft GnuPG Project 4 Intended status: Informational January 31, 2017 5 Expires: August 4, 2017 7 OpenPGP Web Key Service 8 draft-koch-openpgp-webkey-service-03 10 Abstract 12 This specification describes a service to locate OpenPGP keys by mail 13 address using a Web service and the HTTPS protocol. It also provides 14 a method for secure communication between the key owner and the mail 15 provider to publish and revoke the public key. 17 Status of This Memo 19 This Internet-Draft is submitted in full conformance with the 20 provisions of BCP 78 and BCP 79. 22 Internet-Drafts are working documents of the Internet Engineering 23 Task Force (IETF). Note that other groups may also distribute 24 working documents as Internet-Drafts. The list of current Internet- 25 Drafts is at http://datatracker.ietf.org/drafts/current/. 27 Internet-Drafts are draft documents valid for a maximum of six months 28 and may be updated, replaced, or obsoleted by other documents at any 29 time. It is inappropriate to use Internet-Drafts as reference 30 material or to cite them other than as "work in progress." 32 This Internet-Draft will expire on August 4, 2017. 34 Copyright Notice 36 Copyright (c) 2017 IETF Trust and the persons identified as the 37 document authors. All rights reserved. 39 This document is subject to BCP 78 and the IETF Trust's Legal 40 Provisions Relating to IETF Documents 41 (http://trustee.ietf.org/license-info) in effect on the date of 42 publication of this document. Please review these documents 43 carefully, as they describe your rights and restrictions with respect 44 to this document. Code Components extracted from this document must 45 include Simplified BSD License text as described in Section 4.e of 46 the Trust Legal Provisions and are provided without warranty as 47 described in the Simplified BSD License. 49 Table of Contents 51 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2 52 2. Notational Conventions . . . . . . . . . . . . . . . . . . . 2 53 3. Web Key Directory . . . . . . . . . . . . . . . . . . . . . . 2 54 3.1. Key Discovery . . . . . . . . . . . . . . . . . . . . . . 3 55 4. Web Key Directory Update Protocol . . . . . . . . . . . . . . 5 56 4.1. The Submission Address . . . . . . . . . . . . . . . . . 6 57 4.2. The Submission Mail . . . . . . . . . . . . . . . . . . . 6 58 4.3. The Confirmation Request . . . . . . . . . . . . . . . . 6 59 4.4. The Confirmation Response . . . . . . . . . . . . . . . . 8 60 4.5. Policy Flags . . . . . . . . . . . . . . . . . . . . . . 9 61 5. Security Considerations . . . . . . . . . . . . . . . . . . . 9 62 6. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 10 63 6.1. Well-Known URI . . . . . . . . . . . . . . . . . . . . . 10 64 7. Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . 10 65 8. Normative References . . . . . . . . . . . . . . . . . . . . 10 66 Appendix A. Sample Protocol Run . . . . . . . . . . . . . . . . 11 67 A.1. Sample Keys . . . . . . . . . . . . . . . . . . . . . . . 11 68 A.2. Sample Messages . . . . . . . . . . . . . . . . . . . . . 12 69 Appendix B. Changes Since -02 . . . . . . . . . . . . . . . . . 16 70 Author's Address . . . . . . . . . . . . . . . . . . . . . . . . 17 72 1. Introduction 74 This memo describes a method to associate OpenPGP keys with a mail 75 address and how to look them up using a web service with a well-known 76 URI. In addition a mail based protocol is given to allow a client to 77 setup such an association and to maintain it. 79 2. Notational Conventions 81 The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", 82 "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this 83 document are to be interpreted as described in [RFC2119]. 85 3. Web Key Directory 87 A major use case for OpenPGP is the encryption of mail. A common 88 difficulty of sending encrypted mails to a new communication partner 89 is to find the appropriate public key of the recipient. Unless an 90 off-channel key exchange has been done, there are no easy ways to 91 discover the required key. The common practice is to search the 92 network of public key servers for a key matching the recipient's mail 93 address. This practise bears the problem that the keyservers are not 94 able to give a positive confirmation that a key actually belongs to 95 the mail addresses given in the key. Further, there are often 96 several keys matching a mail address and thus one needs to pick a key 97 on good luck. This is clearly not a secure way to setup an end-to- 98 end encryption. Even if the need for a trusted key for an initial 99 mail message is relinquished, a non-authenticated key may be a wrong 100 one and the actual recipient would receive a mail which she can't 101 decrypt, due to the use of a wrong key. 103 Methods to overcome this problem are 105 o sending an initial unencrypted message with the public key 106 attached, 108 o using the OpenPGP DANE protocol to lookup the recipients key via 109 the DNS. 111 The first method has the obvious problems of not even trying to 112 encrypt the initial mail, an extra mail round-trip, and problems with 113 unattended key discovery. 115 The latter method works fine but requires that mail providers need to 116 set up a separate DNS resolver to provide the key. The 117 administration of a DNS zone is often not in the hands of small mail 118 installations. Thus an update of the DNS resource records needs to 119 be delegated to the ISP running the DNS service. Further, DNS 120 lookups are not encrypted and missing all confidentially. Even if 121 the participating MUAs are using STARTTLS to encrypt the mail 122 exchange, a DNS lookup for the key unnecessarily identifies the 123 local-part of the recipients mail address to any passive 124 eavesdroppers. 126 This memo specified a new method for key discovery using an encrypted 127 https connection. 129 3.1. Key Discovery 131 Although URIs are able to encode all kind of characters, 132 straightforward implementations of a key directory may want to store 133 the local-part of a mail address directly in the file system. This 134 forbids the use of certain characters in the local-part. To allow 135 for such an implementation method the URI uses an encoded form of the 136 local-part which can be directly mapped to a file name. 138 OpenPGP defines its User IDs, and thus the mail address, as UTF-8 139 strings. To help with the common pattern of using capitalized names 140 (e.g. "Joe.Doe@example.org") for mail addresses, and under the 141 premise that almost all MTAs treat the local-part case-insensitive 142 and that the domain-part is required to be compared case-insensitive 143 anyway, all upper-case ASCII characters in a User ID are mapped to 144 lowercase. Non-ASCII characters are not changed. 146 The so mapped local-part is hashed using the SHA-1 algorithm. The 147 resulting 160 bit digest is encoded using the Z-Base-32 method as 148 described in [RFC6189], section 5.1.6. The resulting string has a 149 fixed length of 32 octets. To form the URI, the following parts are 150 concatenated: 152 o The scheme "https://", 154 o the domain-part, 156 o the string "/.well-known/openpgpkey/hu/", 158 o and the above constructed 32 octet string. 160 For example the URI to lookup the key for Joe.Doe@Example.ORG is: 162 https://example.org/.well-known/openpgpkey/ 163 hu/iy9q119eutrkn8s1mk4r39qejnbu3n5q 165 (line has been wrapped for rendering purposes) 167 DNS SRV resource records ([RFC2782]) may be used to query a different 168 host or a port other than 443. For example: 170 _openpgpkey._tcp.example.org. IN SRV 0 0 8443 wkd.example.org. 172 changes the above to query the host "wkd.example.org" at port 8443 173 instead of the host "gnupg.org" at port 443. The target (in the 174 example "wkd.example.org") MUST be a sub-domain of the domain-part 175 (here "example.org"). If the target is not a sub-domain, the SRV RR 176 MUST be be ignored. The recommended name for the sub-domain is 177 "wkd". 179 The HTTP GET method MUST return the binary representation of the 180 OpenPGP key for the given mail address. The key needs to carry a 181 User ID packet ([RFC4880]) with that mail address. Note that the key 182 may be revoked or expired - it is up to the client to handle such 183 conditions. To ease distribution of revoked keys, a server may 184 return revoked keys in addition to a new key. The keys are returned 185 by a single request as concatenated key blocks. 187 The server MUST accept the HTTP HEAD method to allow a client to 188 check for the existence of a key. 190 The server SHOULD use "application/octet-string" as the Content-Type 191 for the data but clients SHOULD also accept any other Content-Type. 192 The server MUST NOT return an ASCII armored version of the key. 194 4. Web Key Directory Update Protocol 196 To put keys into the key directory a protocol to automate the task is 197 desirable. The protocol defined here is entirely based on mail and 198 the assumption that a mail provider can securely deliver mail to the 199 INBOX of a user (e.g. an IMAP folder). Note that the same protocol 200 may also be used for submitting keys for use with OpenPGP DANE. 202 We assume that the user already created a key for her mail account 203 alice@example.org. To install the key at her provider's Web Key 204 Directory, she performs the following steps: 206 1. She retrieves a file which contains one line with the mail 207 address used to submit the key to the mail provider. The DNS SRV 208 rules described for the Web Key Directory apply here as well. 209 See below for the syntax of that file. For a mail address at the 210 domain "example.org" the URI of the file is 212 https://example.org/.well-known/openpgpkey/submission-address 214 2. She sends her key using SMTP (or any other transport mechanism) 215 to the provider using the submission address and key format as 216 specified by PGP/MIME. 218 3. The provider checks that the received key has a User ID which 219 matches an account name of the provider. 221 4. The provider sends an encrypted message containing a nonce and 222 the fingerprint of the key to the mail account of the user. Note 223 that a similar scheme is used by the well known caff(1) tool to 224 help with key signing parties. 226 5. A legitimate user will be able to decrypt the message because she 227 created the key and is in charge of the private key. This step 228 verifies that the submitted key has actually been created by the 229 owner of the account. 231 6. The user sends the decrypted nonce back to the submission address 232 as a confirmation that the private key is owned by her and that 233 the provider may now publish the key. Although technically not 234 required, it is suggested that the mail to the provider is 235 encrypted. The public key for this is retrieved using the key 236 lookup protocol described above. 238 7. The provider receives the nonce, matches it with its database of 239 pending confirmations and then publishes the key. Finally the 240 provider sends a mail back to the user to notify her of the 241 publication of her key. 243 The message data structures used for the above protocol are specified 244 in detail below. In the following sections the string "WELLKNOWN" 245 denotes the first part of an URI specific for a domain. In the 246 examples the domain "example.org" is assumed, thus 248 WELLKNOWN := https://example.org/.well-known/openpgpkey 250 The term "target key" denotes the to be published key, the term 251 "submission key" the key associated with the submission-address of 252 the mail provider. 254 4.1. The Submission Address 256 The address of the submission file is 258 WELLKNOWN/submission-address 260 The file consists of exactly one line, terminated by a LF, or the 261 sequence of CR and LF, with the full mail address to be used for 262 submission of a key to the mail provider. For example the content of 263 the file may be 265 key-submission-example.org@directory.example.org 267 4.2. The Submission Mail 269 The mail used to submit a key to the mail provider MUST comply to the 270 PGP/MIME specification ([RFC3156], section 7), which states that the 271 Content-Type must be "application/pgp-keys", there are no required or 272 optional parameters, and the body part contains the ASCII-armored 273 transferable Public Key Packets as defined in [RFC4880], section 274 11.1. 276 The mail provider MUST publish a key capable of signing and 277 encryption for the submission-address in the Web Key Directory or via 278 DANE. The key to be published MUST be submitted using a PGP/MIME 279 encrypted message ([RFC3156], section 4). The message MUST NOT be 280 signed (because the authenticity of the signing key has not yet been 281 confirmed). After decryption of the message at the mail provider a 282 single "application/pgp-keys" part, as specified above, is expected. 284 4.3. The Confirmation Request 286 The mail provider sends a confirmation mail in response to a received 287 key publication request. The message MUST be sent from the 288 submission-address of the mail provider to the mail address extracted 289 from the target key. The message needs to be a PGP/MIME signed 290 message using the submission key of the provider for the signature. 291 The signed message MUST have two parts: 293 The first part MUST have "text" as its Content-Type and can be used 294 to explain the purpose of the mail. For example it may point to this 295 RFC and explain on how to manually perform the protocol. 297 The second part MUST have "application/vnd.gnupg.wkd" as its Content- 298 Type and carry an OpenPGP encrypted message in ASCII Armor format. 299 The message MUST be encrypted to the target key and MUST NOT be 300 signed. After decryption a text file in the Web Key data format must 301 be yielded. 303 That data format consists of name-value pairs with one name-value 304 pair per LF or CR+LF terminated line. Empty lines are allowed and 305 will be ignored by the receiver. A colon is used to terminate a 306 name. 308 In a confirmation request the following names MUST be send in the 309 specified order: 311 o "type": The value must be "confirmation-request". 313 o "sender": This is the mailbox the user is expected to sent the 314 confirmation response to. The value must match the mailbox part 315 of the "From:" address of this request. Exactly one address MUST 316 be given. 318 o "address": The value is the addr-spec part of the target key's 319 mail address. The value SHOULD match the addr-spec part of the 320 recipient's address. The value MUST be UTF-8 encoded as required 321 for an OpenPGP User ID. 323 o "fingerprint": The value is the fingerprint of the target key. 324 The fingerprint is given in uppercase hex encoding without any 325 interleaving spaces. 327 o "nonce": The value is a string with a minimum length of 16 octets 328 and a maximum length of 64 octets. The string must entirely be 329 made up of random ASCII letters or digits. This nonce will be 330 sent back to the mail provider as proof that the recipient is the 331 legitimate owner of the target-key. 333 The receiver of that message is expected to verify the outer 334 signature and disregard the entire message if it can't be verified or 335 has not been signed by the key associated with the submission 336 address. 338 After the message as been verified the receiver decrypts the second 339 part of the message, checks that the "fingerprint" matches the target 340 key, checks that the "address" matches a User ID of the target key, 341 and checks the other constrains of the request format. If any 342 constraint is not asserted, or the fingerprint or User ID do not 343 match the target key, or there is no pending publication requests 344 (i.e. a mail recently sent o the submission address), the user MAY be 345 notified about this fake confirmation attempt. 347 In other cases the confirmation request is legitimate and the MUA 348 shall silently send a response as described in the next section. 350 The rationale for the outer signature used with this request is to 351 allow early detection of spam mails. This can be done prior to the 352 decryption step and avoids asking the user to enter a passphrase to 353 perform the decryption for a non-legitimate message. The use of a 354 simple encrypted attachment, instead of using PGP/MIME encryption, is 355 to convey the Content-Type of that attachment in the clear and also 356 to prevent automatic decryption of that attachment by PGP/MIME aware 357 clients. The MUA may in fact detect this confirmation request and 358 present a customized dialog for confirming that request. 360 4.4. The Confirmation Response 362 A response to a confirmation request MUST only be send in the 363 positive case; there is no negative confirmation response. A mail 364 service provider is expected to cancel a pending key submission after 365 a suitable time without a confirmation. The mail service provider 366 SHOULD NOT retry the sending of a confirmation request after the 367 first request has been send successfully. 369 The user MUST send the confirmation response from her target mail 370 address to the "from" address of the confirmation request. The 371 message MUST be signed and encrypted using the PGP/MIME Combined 372 format ([RFC3156], section 6.2). The signing key is the target key 373 and the encryption key is the key associated with the provider's 374 submission address. 376 The Content-Type used for the plaintext message MUST also be 377 "application/vnd.gnupg.wkd". The format is the same as described 378 above for the Confirmation Request. The body must contain three 379 name-value pairs in this order: 381 o "type": The value must be "confirmation-response". 383 o "sender": The value must match the mailbox part of the "From:" 384 address of this response. Exactly one address MUST be given. 386 o "nonce": The value is the value of the "nonce" parameter from the 387 confirmation request. 389 4.5. Policy Flags 391 For key generation and submission it is sometimes useful to tell the 392 client about certain properties of the mail provider in advance. 393 This can be done with a file at the URL 395 WELLKNOWN/policy 397 The file contains keywords and optioanlly values, one per line with 398 each line terminated by a LF or the sequence of CR and LF. Empty 399 lines and lines starting with a '#' character are considered comment 400 lines. A keyword is made up of lowercase letters, digits, hyphens, 401 or dots. An underscore is allowed as a name space delimiters; see 402 below. The first character must be a letter. Keywords which are 403 defined to require a value are directly followed by a colon and then 404 after optional white space the value. Clients MUST use case- 405 insensitive matching for the keyword. 407 Currently defined keywords are: 409 o "mailbox-only": The mail server provider does only accept keys 410 with only a mailbox in the User ID. In particular User IDs with a 411 real name in addition to the mailbox will be rejected as invalid. 413 o "dane-only": The mail server provider does not run a Web Key 414 Directory but only an OpenPGP DANE service. The Web Key Directory 415 Update protocol is used to update the keys for the DANE service. 417 o "auth-submit": The submission of the mail to the server is done 418 using an authenticated connection. Thus the submitted key will be 419 published immediately without any confirmation request. 421 More keywords will be defined in updates to this I-D. There is no 422 registry except for this document. For experimental use of new 423 features or for provider specific settings, keywords MUST be prefixed 424 with a domain name and an underscore. 426 5. Security Considerations 428 The use of SHA-1 for the mapping of the local-part to a fixed string 429 is not a security feature but merely used to map the local-part to a 430 fixed-sized string made from a well defined set of characters. It is 431 not intended to conceal information about a mail address. 433 The domain name part of the mail address is not part of the hash to 434 avoid problems with internationalized domain names. Instead a 435 separate URL is required for each domain name. 437 The use of DNS SRV records reduces the certainty that a mail address 438 belongs to a domain. For example an attacker may change the target 439 to a host in a sub-domain under their control and thus gain full 440 control over all keys. An implementation may want to weight the 441 certainty of a mapping different if it has been retrieved via a sub- 442 domain and in particular if a non-recommended name is used for the 443 sub-domain. 445 6. IANA Considerations 447 6.1. Well-Known URI 449 IANA is requested to assign a well-known URI in the "Well-Known URIs" 450 registry as defined by [RFC5785]: 452 URI suffix: openpgpkey 454 Change controller: IETF 456 Specification document: This 458 7. Acknowledgments 460 The author would like to acknowledge the help of the individuals who 461 kindly voiced their opinions on the GnuPG mailing lists, in 462 particular, the help of Bernhard Reiter and Guilhem Moulin. 464 8. Normative References 466 [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate 467 Requirement Levels", BCP 14, RFC 2119, March 1997. 469 [RFC2782] Gulbrandsen, A., Vixie, P., and L. Esibov, "A DNS RR for 470 specifying the location of services (DNS SRV)", RFC 2782, 471 DOI 10.17487/RFC2782, February 2000, 472 . 474 [RFC3156] Elkins, M., Del Torto, D., Levien, R., and T. Roessler, 475 "MIME Security with OpenPGP", RFC 3156, August 2001. 477 [RFC4880] Callas, J., Donnerhacke, L., Finney, H., Shaw, D., and R. 478 Thayer, "OpenPGP Message Format", RFC 4880, November 2007. 480 [RFC5785] Nottingham, M. and E. Hammer-Lahav, "Defining Well-Known 481 Uniform Resource Identifiers (URIs)", RFC 5785, DOI 482 10.17487/RFC5785, April 2010, 483 . 485 [RFC6189] Zimmermann, P., Johnston, A., Ed., and J. Callas, "ZRTP: 486 Media Path Key Agreement for Unicast Secure RTP", RFC 487 6189, DOI 10.17487/RFC6189, April 2011, 488 . 490 Appendix A. Sample Protocol Run 492 The following non-normative example can be used by implementors as 493 guidance. 495 Note that GnuPG version 2.1.12 supports the key discovery described 496 in version -00 of this document (auto-key-locate method "wkd"). 497 Version 2.1.16 can run the protocol decribed in this document but is 498 also able to run the protocol version specified by -01. 500 A.1. Sample Keys 502 This is the provider's submission key: 504 -----BEGIN PGP PRIVATE KEY BLOCK----- 506 lFgEV/TAohYJKwYBBAHaRw8BAQdAB/k9YQfSTI8qQqqK1KimH/BsvzsowWItSQPT 507 FP+fOC4AAP46uJ3Snno3Vy+kORye3rf0VvWvuz82voEQLxG6WpfHhREEtBprZXkt 508 c3VibWlzc2lvbkBleGFtcGxlLm5ldIh5BBMWCAAhBQJX9MCiAhsDBQsJCAcCBhUI 509 CQoLAgQWAgMBAh4BAheAAAoJEKhtNooW0cqEWMUA/0e9XaeptszWC9ZvPg8INL6a 510 BvRqPBYGU7PGmuXsxBovAQDyckOykG0UAfHVyN1w4gSK/biMcnqVr857i8/HuvjW 511 C5xdBFf0wKISCisGAQQBl1UBBQEBB0Apvaoe4MtSEJ1fpds/4DFl2kXXBpnVji/s 512 Wg9btdthNQMBCAcAAP9FJX99T1LEJzBnvBBnc6bimnT6/1OKM9RdO4R0/uVP6BFL 513 iGEEGBYIAAkFAlf0wKICGwwACgkQqG02ihbRyoTlGwD9FBr92osjL7HkhhZZ7Z2D 514 My3b9zpoZeMjvPg5YPqpdKMA/jhZoHuZCRMBYf7YRFb8aXtuyetDFZYrkjnum+OG 515 HFAD 516 =Hnwd 517 -----END PGP PRIVATE KEY BLOCK----- 519 This is the target key to be published: 521 -----BEGIN PGP PRIVATE KEY BLOCK----- 523 lFgEV2o9XRYJKwYBBAHaRw8BAQdAZ8zkuQDL9x7rcvvoo6s3iEF1j88Dknd9nZhL 524 nTEoBRkAAP94nCZMM4WY2IORXfM6phLGSz3RsHvs/vA1Opaus4+R3BKJtBtwYXRy 525 aWNlLmx1bXVtYmFAZXhhbXBsZS5uZXSIeQQTFggAIQUCV2o9XQIbAwULCQgHAgYV 526 CAkKCwIEFgIDAQIeAQIXgAAKCRATlWNoKgINCpkNAQDFDcwJUzsxu7aJUiPdpYXj 527 4uVarrXakxEE8mGFotWhLAD9GH4rqLDYIE3NKEU0s+Okt4tEIwJaV8H1NNPPPMiK 528 3g2cXQRXaj2NEgorBgEEAZdVAQUBAQdAFnnmZc99TuKk5iCq9wmYZUVF2RcXN2Cs 529 qAl8iGQQUWsDAQgHAAD/VN/VGmlcwGBPcLTya2hfU4t37nMcFCKdNSXjJ5DFA0AP 530 PohhBBgWCAAJBQJXaj2NAhsMAAoJEBOVY2gqAg0Ky4UA/0GmVaXzXemLvv1Xw4yx 531 Eaz/KfKKGc4RJ+38fyqUzw8NAQCohQ+ki3I5f84EXLZEiUiLsnVtOn1HNxvND/gW 532 TiFZBA== 533 =GHi7 534 -----END PGP PRIVATE KEY BLOCK----- 536 A.2. Sample Messages 538 The first message triggeres the publication requests. 540 From: patrice.lumumba@example.net 541 To: key-submission@example.net 542 Subject: Key publishing request 543 MIME-Version: 1.0 544 Content-Type: multipart/encrypted; 545 protocol="application/pgp-encrypted"; 546 boundary="=-=01-e8k41e11ob31eefa36wo=-=" 547 Date: Wed, 05 Oct 2016 10:15:51 +0000 549 --=-=01-e8k41e11ob31eefa36wo=-= 550 Content-Type: application/pgp-encrypted 552 Version: 1 554 --=-=01-e8k41e11ob31eefa36wo=-= 555 Content-Type: application/octet-stream 557 -----BEGIN PGP MESSAGE----- 559 hF4DUgLY5tvmW2sSAQdAR1AcqvFpQe/fHRZbf0xcnl9Tb+AtwaX2yZnZXGELGHsw 560 1/e3E0JptwM5tpRAVe71ooF8Zq4jl76ZgQKfj/SyjpLJxyoEDy2N5wTQaqW4JtML 561 0ukB1vh7dIRDxBJX/LQIJC0wz8o1Q3vjcLJKFFvDb7YrerABpPIzwOAupcgIbQHj 562 5m1+2WU5CL8ffyJy2h1jV2X4OnvWF1Sn6J6SVD6DfZpOPRt9TxSemJrN1LJ3lG0N 563 ts8AuYmCOeC1H2r5TYyxqkC98JF8+Nvyxd/fwne8IOjK9uixkNMC5H9/ZOH0YWCb 564 wBnNB4iXuym4OIPxiLkDymsVF0ww/XrODE9Y259EGmO45VFNrJAX3HFs9/PcMCVk 565 n2qMyEkr8LHiXeEPun6Z54RHUPYv2cUkEZ0hhSJ+rtBxkc/5D/cAScCEXRKFSKEF 566 jLJAvLK/u/ga5DAzVai+vh6b6Bq+YVPaD9GWMhWj4CgR90p9LULi6S/Hzwhv9Wzf 567 8fJoJOaDjyvRDgr09jYLWamxkS9NWxqwy6MXJvxwbNdd5XtqiW4Y4o0Ll1hDJhxR 568 ljn/XvotXKwhKN+4QGhIXDVt4Dl4XxS5ptWfVTau8W8DYqDsU2obEcfsirZv53M1 569 Q9FCD8CD9+dkBt8VAJekCWVhEltcRHxlrznbk2jxm93xSD2o6gZ5X0VSaSUXyEhm 570 J+8F3gyTHGgbq/TgyjFoockWh5EtGgAFuWvmPJCF5PO/UaNeoKwgwSJBu6oTXkHx 571 R4nvvMRcj5UgTsKpZ79NiDQukbjG5ScNT5TCUiiZsBXBqBx3fD61EH6cAuh4P3Kr 572 iM7PY4fwAHo890Dx+Qlt 573 =WIhx 574 -----END PGP MESSAGE----- 576 --=-=01-e8k41e11ob31eefa36wo=-=-- 578 The server decrypts this message to 579 Content-Type: application/pgp-keys 581 -----BEGIN PGP PUBLIC KEY BLOCK----- 583 mDMEV2o9XRYJKwYBBAHaRw8BAQdAZ8zkuQDL9x7rcvvoo6s3iEF1j88Dknd9nZhL 584 nTEoBRm0G3BhdHJpY2UubHVtdW1iYUBleGFtcGxlLm5ldIh5BBMWCAAhBQJXaj1d 585 AhsDBQsJCAcCBhUICQoLAgQWAgMBAh4BAheAAAoJEBOVY2gqAg0KmQ0BAMUNzAlT 586 OzG7tolSI92lhePi5VqutdqTEQTyYYWi1aEsAP0YfiuosNggTc0oRTSz46S3i0Qj 587 AlpXwfU00888yIreDbg4BFdqPY0SCisGAQQBl1UBBQEBB0AWeeZlz31O4qTmIKr3 588 CZhlRUXZFxc3YKyoCXyIZBBRawMBCAeIYQQYFggACQUCV2o9jQIbDAAKCRATlWNo 589 KgINCsuFAP9BplWl813pi779V8OMsRGs/ynyihnOESft/H8qlM8PDQEAqIUPpIty 590 OX/OBFy2RIlIi7J1bTp9RzcbzQ/4Fk4hWQQ= 591 =qRfF 592 -----END PGP PUBLIC KEY BLOCK----- 594 and returns this confirmation request 595 From: key-submission@example.net 596 To: patrice.lumumba@example.net 597 Subject: Confirm your key publication 598 MIME-Version: 1.0 599 Content-Type: multipart/encrypted; 600 protocol="application/pgp-encrypted"; 601 boundary="=-=01-wrzqued738dfx4x97u7y=-=" 602 Date: Wed, 05 Oct 2016 10:16:57 +0000 604 --=-=01-wrzqued738dfx4x97u7y=-= 605 Content-Type: application/pgp-encrypted 607 Version: 1 609 --=-=01-wrzqued738dfx4x97u7y=-= 610 Content-Type: application/octet-stream 612 -----BEGIN PGP MESSAGE----- 614 hF4DkYWHjk/NdMASAQdAluQeqhECpU2T0zEyBAEbFzhLkpubN160wjkFCrtUc0Mw 615 FwYgM2fp9cvTMdJ/xjkvmAcIEOT4AY/hn1yFQ4z0KG0gCkSac+8mkDylnPdxlXYw 616 0sBSAXlbqpVA7eUpFuU2Zs10zbIXxlwe6osR5wUIJut/RCOsYQmfvxC55x8mUX5/ 617 zgTnNzlMzye5ws4pTgAeQm2x0Yv018L8IZgY5KxwJLBzlss0wLZ45ZcS80hR11Fx 618 NCow1fKF8lMnOJxagTEOih807nctz8vT5bR1gx0d7N3LM+th8nAg9/6Ghf1XTpLo 619 MzwGW0FtOG7Dg1Uxbw2bjaOuRBeh6IIpmNAw1pmIfnNu7PpoRydU5w1K/R8MT06z 620 MKdJ7IW5mVGes9EGnG3e4mjuILvNaZhfYy+a73IhDSaPm3oqdl1Qx7tbNg6lGjn6 621 KStCYAcPGPp3m7aWkfsPGThOVRhEXqaFFywfwSVEj1pdIRjDFA== 622 =Cdjh 623 -----END PGP MESSAGE----- 625 --=-=01-wrzqued738dfx4x97u7y=-=-- 627 The client decrypts the attachment as 629 Content-Type: application/vnd.gnupg.wks 630 Content-Transfer-Encoding: 8bit 632 type: confirmation-request 633 sender: key-submission@example.net 634 address: patrice.lumumba@example.net 635 fingerprint: B21DEAB4F875FB3DA42F1D1D139563682A020D0A 636 nonce: f5pscz57zj6fk11wekk8gx4cmrb659a7 638 creates this response 639 Content-Type: application/vnd.gnupg.wks 640 Content-Transfer-Encoding: 8bit 642 type: confirmation-response 643 sender: key-submission@example.net 644 address: patrice.lumumba@example.net 645 nonce: f5pscz57zj6fk11wekk8gx4cmrb659a7 647 and sends it encrypted to the server 649 From: patrice.lumumba@example.net 650 To: key-submission@example.net 651 Subject: Key publication confirmation 652 MIME-Version: 1.0 653 Content-Type: multipart/encrypted; 654 protocol="application/pgp-encrypted"; 655 boundary="=-=01-iacqg4og4pqz11a5cg1o=-=" 656 Date: Wed, 05 Oct 2016 10:18:52 +0000 658 --=-=01-iacqg4og4pqz11a5cg1o=-= 659 Content-Type: application/pgp-encrypted 661 Version: 1 663 --=-=01-iacqg4og4pqz11a5cg1o=-= 664 Content-Type: application/octet-stream 666 -----BEGIN PGP MESSAGE----- 668 hF4DUgLY5tvmW2sSAQdAnB1C3PMjS4AsGU0qaCqBdWQO5i6blWEyZrEsY+JZY1Qw 669 ooNq7zdVWOHhL9LPGAALAgoL3Qfz+dN2u5QamSQ/LJ2c8M0XipNs3lqlNH63yQN1 670 0sAmAc3W8xkwul+rf6OLK/gMi6WzM4fnUhd4D1LJGIJoNUN0l3636C7ecOt2lkMl 671 5bVAYg/SyMT3ymyfQnvtiem2T5DSnPsS1g6n6QNXWvkqvX9yGxNsNDJEHTuGJB8k 672 OJoRlfWQTEo6pgA89febWl1EdeM1pPLstQ2uZE8NPjXoY1nMxAlu+iPYsR41/4sg 673 dqwOv5BPLh/GIat8hh9SPWCA9iKlgSQ/EIv5DpjQogEzpriT55dkgfvSVYIAcOdO 674 ShZ91YKkcZffevdY72omqTk10a1SUXehPooIlRFmroDsi3VDaRKrUIo= 675 =7uve 676 -----END PGP MESSAGE----- 678 --=-=01-iacqg4og4pqz11a5cg1o=-=-- 680 Appendix B. Changes Since -02 682 o Specified the use of DNS SRV. 684 Author's Address 686 Werner Koch 687 GnuPG Project 689 Email: wk@gnupg.org 690 URI: https://gnupg.org