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commit 7703092b35dbd0084c26d277bb03cb7e21889add
Author: Werner Koch <wk at gnupg.org>
Date: Fri May 6 09:51:55 2016 +0200
drafts: Released first version of openpgp-webkey-service.
diff --git a/misc/id/openpgp-webkey-service/abstract.mkd b/misc/id/openpgp-webkey-service/abstract.mkd
new file mode 100644
index 0000000..d8596be
--- /dev/null
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@@ -0,0 +1,4 @@
+This specification describes a service to locate OpenPGP keys by mail
+address using a Web service and the HTTPS protocol. It also provides
+a method for secure communication between the key owner and the mail
+provider to publish and revoke the public key.
diff --git a/misc/id/openpgp-webkey-service/back.mkd b/misc/id/openpgp-webkey-service/back.mkd
new file mode 100644
index 0000000..78d234b
--- /dev/null
+++ b/misc/id/openpgp-webkey-service/back.mkd
@@ -0,0 +1,23 @@
+# Test Vectors
+
+For help implementing this specification a non-normative example is
+given:
+
+## Sample key
+
+ TODO
+
+## Software Notes
+
+ GnuPG supports the key discovery described in this document since
+ version 2.1.12. To use it, the new method "wkd" needs to be used
+ with the --auto-key-locate option.
+
+# Changes
+
+ - This is the initial draft.
+
+## TODO
+
+ - What about authenticated submission?
+ - Describe how to handle a key with several User IDs.
diff --git a/misc/id/openpgp-webkey-service/draft-koch-openpgp-webkey-service-00.txt b/misc/id/openpgp-webkey-service/draft-koch-openpgp-webkey-service-00.txt
new file mode 100644
index 0000000..4f271fc
--- /dev/null
+++ b/misc/id/openpgp-webkey-service/draft-koch-openpgp-webkey-service-00.txt
@@ -0,0 +1,560 @@
+
+
+
+
+Network Working Group W. Koch
+Internet-Draft GnuPG Project
+Intended status: Informational May 6, 2016
+Expires: November 7, 2016
+
+
+ OpenPGP Web Key Service
+ draft-koch-openpgp-webkey-service-00
+
+Abstract
+
+ This specification describes a service to locate OpenPGP keys by mail
+ address using a Web service and the HTTPS protocol. It also provides
+ a method for secure communication between the key owner and the mail
+ provider to publish and revoke the public key.
+
+Status of This Memo
+
+ This Internet-Draft is submitted in full conformance with the
+ provisions of BCP 78 and BCP 79.
+
+ Internet-Drafts are working documents of the Internet Engineering
+ Task Force (IETF). Note that other groups may also distribute
+ working documents as Internet-Drafts. The list of current Internet-
+ Drafts is at http://datatracker.ietf.org/drafts/current/.
+
+ Internet-Drafts are draft documents valid for a maximum of six months
+ and may be updated, replaced, or obsoleted by other documents at any
+ time. It is inappropriate to use Internet-Drafts as reference
+ material or to cite them other than as "work in progress."
+
+ This Internet-Draft will expire on November 7, 2016.
+
+Copyright Notice
+
+ Copyright (c) 2016 IETF Trust and the persons identified as the
+ document authors. All rights reserved.
+
+ This document is subject to BCP 78 and the IETF Trust's Legal
+ Provisions Relating to IETF Documents
+ (http://trustee.ietf.org/license-info) in effect on the date of
+ publication of this document. Please review these documents
+ carefully, as they describe your rights and restrictions with respect
+ to this document. Code Components extracted from this document must
+ include Simplified BSD License text as described in Section 4.e of
+ the Trust Legal Provisions and are provided without warranty as
+ described in the Simplified BSD License.
+
+
+
+
+Koch Expires November 7, 2016 [Page 1]
+
+Internet-Draft OpenPGP Web Key Service May 2016
+
+
+Table of Contents
+
+ 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2
+ 2. Notational Conventions . . . . . . . . . . . . . . . . . . . 2
+ 3. Web Key Directory . . . . . . . . . . . . . . . . . . . . . . 2
+ 3.1. Key Discovery . . . . . . . . . . . . . . . . . . . . . . 3
+ 4. Web Key Directory Update Protocol . . . . . . . . . . . . . . 4
+ 4.1. The Submission Address . . . . . . . . . . . . . . . . . 5
+ 4.2. The Submission Mail . . . . . . . . . . . . . . . . . . . 6
+ 4.3. The Confirmation Request . . . . . . . . . . . . . . . . 6
+ 4.4. The Confirmation Response . . . . . . . . . . . . . . . . 7
+ 4.5. Policy Flags . . . . . . . . . . . . . . . . . . . . . . 8
+ 5. Security Considerations . . . . . . . . . . . . . . . . . . . 8
+ 6. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 9
+ 6.1. Well-Known URI . . . . . . . . . . . . . . . . . . . . . 9
+ 7. Normative References . . . . . . . . . . . . . . . . . . . . 9
+ Appendix A. Test Vectors . . . . . . . . . . . . . . . . . . . . 9
+ A.1. Sample key . . . . . . . . . . . . . . . . . . . . . . . 10
+ A.2. Software Notes . . . . . . . . . . . . . . . . . . . . . 10
+ Appendix B. Changes . . . . . . . . . . . . . . . . . . . . . . 10
+ B.1. TODO . . . . . . . . . . . . . . . . . . . . . . . . . . 10
+ Author's Address . . . . . . . . . . . . . . . . . . . . . . . . 10
+
+1. Introduction
+
+ This memo describes a method to associate OpenPGP keys with a mail
+ address and now to look them up using a web service with a well-known
+ URI. In addition a mail based protocol is given to allow a client to
+ setup such an association and to maintain it.
+
+2. Notational Conventions
+
+ The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
+ "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this
+ document are to be interpreted as described in [RFC2119].
+
+3. Web Key Directory
+
+ A major use case for OpenPGP is the encryption of mail. A common
+ difficulty of sending encrypted mails to a new communication partner
+ is to find the appropriate public key of the recipient. Unless an
+ off-channel key exchange has been done, there are no easy ways to
+ discover the required key. The common practice is to search the
+ network of public key servers for a key matching the recipient's mail
+ address. This practise bears the problem that the keyservers are not
+ able to give a positive confirmation that a key actually belongs to
+ the mail addresses given in the key. Further, there are often
+ several keys matching a mail address and thus one needs to pick a key
+
+
+
+Koch Expires November 7, 2016 [Page 2]
+
+Internet-Draft OpenPGP Web Key Service May 2016
+
+
+ on good luck. This is clearly not a secure way to setup an end-to-
+ end encryption. Even if the need for a trusted key for an initial
+ mail message is relinquished, a non-authenticated key may be a wrong
+ one and the actual recipient would receive a mail which she can't
+ decrypt, due to the use of a wrong key.
+
+ Methods to overcome this problem are
+
+ o sending an initial unencrypted messages with the public key
+ attached,
+
+ o using the OpenPGP DANE protocol to lookup the recipients key via
+ the DNS.
+
+ The first method has the obvious problems of not even trying to
+ encrypt the initial mail, an extra mail round-trip, and problems with
+ unattended key discovery.
+
+ The latter method works fine but requires that mail providers need to
+ set up a separate DNS resolver to provide the key. The
+ administration of a DNS zone is often not in the hands of small mail
+ installations. Thus an update of the DNS resource records needs to
+ be delegated to the ISP running the DNS service. Further, DNS
+ lookups are not encrypted and missing all confidentially. Even if
+ the participating MUAs are using STARTTLS to encrypt the mail
+ exchange, a DNS lookup for the key unnecessary identifies the local-
+ part of the recipients mail address to any passive eavesdroppers.
+
+ This memo specified a new method for key discovery using an encrypted
+ https connection.
+
+3.1. Key Discovery
+
+ Although URIs are able to encode all kind of characters,
+ straightforward implementations of a key directory may want to store
+ the "local-part" of a mail address directly in the file system. This
+ forbids the use of certain characters in the "local-part". To allow
+ for such an implementation method the URI uses an encoded form of the
+ "local-part" which can be directly mapped to a file name.
+
+ OpenPGP defines its User IDs, and thus the mail address, as UTF-8
+ strings. To help with the common pattern of using capitalized names
+ (e.g. "Joe.Doe at example.org") for mail addresses, and under the
+ premise that almost all MTAs treat the "local-part" case-insensitive
+ and that the "domain-part" is required to be compared case-
+ insensitive anyway, all upper-case ASCII characters in a User ID are
+ mapped to lowercase. Non-ASCII characters are not changed.
+
+
+
+
+Koch Expires November 7, 2016 [Page 3]
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+
+
+ The so mapped "local-part" is hashed using the SHA-1 algorithm. The
+ resulting 160 bit digest is encoded using the Z-Base-32 method as
+ described in [RFC6189], section 5.1.6. The resulting string has a
+ fixed length of 32 octets. To form the URI, the scheme "https://" is
+ concatenated with the mapped "domain-part", the fixed string "./well-
+ known/openpgpkey/hu/", the "domain-part" again, and the above
+ constructed 32 octet string.
+
+ For example the URI to lookup the key for Joe.Doe at Example.ORG is:
+
+ https://example.org/.well-known/openpgpkey/
+ hu/example.org/iy9q119eutrkn8s1mk4r39qejnbu3n5q
+
+ (line has been wrapped for rendering purposes)
+
+ The HTTP GET method MUST return the binary representation of the
+ OpenPGP key for the given mail address. The key needs to carry a
+ User ID packet ([RFC4880]) with that mail address. Note that the key
+ may be revoked or expired - it is up to the client to handle such
+ conditions. The server MUST also accept a HEAD method so that a
+ client may only check for the existence of a key.
+
+ The server SHOULD return "application/pgp-key" as the content-type
+ for the data but clients MUST also accept "application/octet-string"
+ as content-type. The server MUST NOT return an ASCII armored version
+ of the key.
+
+4. Web Key Directory Update Protocol
+
+ To put keys into the key directory a protocol to automate the task is
+ desirable. The protocol defined here is entirely based on mail and
+ the assumption that a mail provider can securely deliver mail to the
+ INBOX of a user (e.g. an IMAP folder). Note that the same protocol
+ may also be used for submitting keys for use with OpenPGP DANE.
+
+ We assume that the user already created a key for her mail account
+ alice at example.org. To install the key at her provider's Web Key
+ Directory, she performs the following steps:
+
+ 1. She retrieves a file which contains one line with the mail
+ address used to submit the key to the mail provider. See below
+ for the syntax of that file. For a mail address at the domain
+ "example.org" the URI of the file is
+
+ https://example.org/.well-known/openpgpkey/submission-address
+
+ 2. She sends her key using SMTP (or any other transport mechanism)
+ to the provider using the submission address. The content-type
+
+
+
+Koch Expires November 7, 2016 [Page 4]
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+
+
+ SHOULD be "application/pgp-key" and the key being a binary
+ attachment (which is then likely base64 encoded). Note that the
+ OpenPGP ASCII armor is not used.
+
+ 3. The provider checks that the received key has a User ID which
+
+ * matches an account name of the provider,
+
+ * and that the from address matches that account.
+
+ 4. The provider sends an encrypted message containing a nonce and
+ the fingerprint of the key to the mail account of the user. Note
+ that a similar scheme is used by the well known caff(1) tool to
+ help with key signing parties.
+
+ 5. A legitimate user will be able to decrypt the message because she
+ created the key and is in charge of the private key. This step
+ verifies that the submitted key has actually been created by the
+ owner of the account.
+
+ 6. The user sends the decrypted nonce back to the submission address
+ as a confirmation that the private key is owned by her and that
+ the provider may now publish the key. Also technically not
+ required, it is suggested that the mail to the provider is
+ encrypted. The public key for this is retrieved using the key
+ lookup protocol described above.
+
+ 7. The provider receives the nonce, matches it with its database of
+ pending confirmations and then publishes the key. Finally the
+ provider sends a mail back to the user to notify her of the the
+ publication of her key.
+
+ The message data structures used for the above protocol are specified
+ in detail below. In the following sections the string "WELLKNOWN"
+ denotes the first part of an URI specific for a domain. In the
+ examples the domain "example.org" is assumed, thus
+
+ WELLKNOWN := https://example.org/.well-known/openpgpkey
+
+ The term "target key" denotes the to be published key, the term
+ "submission key" the key associated with the submission-address of
+ the mail provider.
+
+4.1. The Submission Address
+
+ The address of the submission file is
+
+ WELLKNOWN/submission-address
+
+
+
+Koch Expires November 7, 2016 [Page 5]
+
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+
+
+ The file consists of exactly one line, terminated by a LF, or the
+ sequence of CR and LF, with the full mail address to be used for
+ submission of a key to the mail provider. For example the content of
+ the file may be
+
+ key-submission-example.org at directory.example.org
+
+4.2. The Submission Mail
+
+ The mail used to submit a key to the mail provider MUST comply to the
+ PGP/MIME specification ([RFC3156], section 7), which states that the
+ Content-Type must be "application/pgp-keys", there are no required or
+ optional parameters, and the body part contains the ASCII-armored
+ transferable Public Key Packets as defined in [RFC4880], section
+ 11.1.
+
+ If the mail provider has published an encryption key for the
+ submission-address in the Web Key Directory, the key to be published
+ MUST be submitted using a PGP/MIME encrypted message ([RFC3156],
+ section 4). The message MUST not be signed (because the authenticity
+ of the signing key has not yet been confirmed). After decryption of
+ the message at the mail provider a single "application/pgp-keys"
+ part, as specified above, is expected.
+
+4.3. The Confirmation Request
+
+ The mail provider sends a confirmation mail in response to a received
+ key publication request. The message SHOULD be sent from the
+ submission-address of the mail provider to the mail address extracted
+ from the target key. The message needs to be encrypted to the target
+ key and MAY be signed by the submission key. PGP/MIME MUST be used
+ for encryption and signing; the Combined method ([RFC3156], section
+ 6.2) MUST be used if the message is to be signed.
+
+ The Content-type used for the plaintext part MUST be "application/
+ vnd.gnupg.wkd". The body consists of name-value pairs with one name-
+ value pair per LF or CR+LF terminated line. Empty lines are allowed
+ and will be ignored by the receiver. A colon is used to terminate a
+ name.
+
+ In a confirmation request the following names MUST be send in the
+ specified order:
+
+ "type" The value must be "confirmation-request".
+
+ "from" This is the mailbox the user is expected to sent the
+ confirmation response to. The value must match the mailbox part
+ of the "From:" address of this request.
+
+
+
+Koch Expires November 7, 2016 [Page 6]
+
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+
+
+ "address" The value is the addr-spec part of the target key's mail
+ address. The value SHOULD match the addr-spec part of the
+ recipient's address. The value MUST be be UTF-8 encoded as
+ required for an OpenPGP User ID.
+
+ "fingerprint" The value is the fingerprint of the target key. The
+ fingerprint is given in uppercase hex encoding without any
+ interleaving spaces.
+
+ "nonce" The value is a string with a minimum length of 16 octets and
+ a maximum length of 64 octets. The string must entirely be made
+ up of random ASCII letters or digits. This nonce will be sent
+ back to the mail provider as proof that the recipient is the
+ legitimate owner of the target-key.
+
+ The receiver of the message decrypts the message, checks that the
+ "fingerprint" matches the target key, checks that the "address"
+ matches a User ID of the target key, and checks the other constrains
+ of the request format. If any constraint is not asserted, or the
+ fingerprint or User ID do not match the target key, or there is no
+ pending publication requests (i.e. a mail recently sent o the
+ submission address), the user MAY be notified about this fake
+ confirmation attempt.
+
+ In other cases the confirmation request is legitimate and the MUA
+ shall silently send a response as described in the next section.
+
+4.4. The Confirmation Response
+
+ A response to a confirmation request MUST only be send in the
+ positive case; there is no negative confirmation response. A mail
+ service provider is expected to cancel a pending key submission after
+ a suitable time without a confirmation. The mail service provider
+ SHOULD not retry the sending of a confirmation request after the
+ first request has been send successfully.
+
+ The user MUST send the confirmation response from her target mail
+ address to the "from" address of the confirmation request. The
+ message MUST be signed and SHOULD be encrypted. The PGP/MIME
+ Combined format MUST be used for encryption and signing ([RFC3156],
+ section 6.2). The encryption key can be taken from the Web Key
+ Directory.
+
+ The Content-type used for the plaintext message MUST also be
+ "application/vnd.gnupg.wkd". The format is the same as described
+ above for the Confirmation Request. The body must contain three
+ name-value pairs in this order:
+
+
+
+
+Koch Expires November 7, 2016 [Page 7]
+
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+
+
+ "type" The value must be "confirmation-response".
+
+ "from" The value must match the mailbox part of the "From:" address
+ of this response.
+
+ "nonce" The value is the value of the "nonce" parameter from the
+ confirmation request.
+
+4.5. Policy Flags
+
+ For key generation and submission it is sometimes useful to tell the
+ client about certain properties of the mail provider in advance.
+ This can be done with a file at the URL
+
+ WELLKNOWN/policy
+
+ The file contains keywords, one per line with each line terminated by
+ a LF or the sequence of CR and LF. Empty lines and lines starting
+ with a '#' character are considered comment lines. A keyword is made
+ up of lowercase letters, digits, hyphens, or dots. An underscore is
+ allowed as a name space delimiters; see below. The first character
+ must be a letter. Clients MUST use case-insensitive matching.
+
+ Currently defined keywords are:
+
+ "mailbox-only" The mail server provider does only accept keys with
+ only a mailbox in the User ID. In particular User IDs with a real
+ name in addition to the mailbox will be rejected as invalid.
+
+ More keywords will be defined in updates to this I-D. There is no
+ registry yet except for this document. For experimental use of new
+ features or for provider specific settings, keywords MUST be prefixed
+ with a domain name and an underscore.
+
+5. Security Considerations
+
+ The use of SHA-1 for the mapping of the "local-part" to a fixed
+ string is not a security feature but merely used to map the local-
+ part to a fixed-sized string made from a well defined set of
+ characters. It is not intended to conceal information about a mail
+ address.
+
+ The domain name part of the mail address is not part of the hash to
+ avoid problems with internationalized domain names. Instead a
+ separate web service is required for each domain name.
+
+
+
+
+
+
+Koch Expires November 7, 2016 [Page 8]
+
+Internet-Draft OpenPGP Web Key Service May 2016
+
+
+6. IANA Considerations
+
+6.1. Well-Known URI
+
+ IANA is requested to assign a well-known URI in the "Well-Known URIs"
+ registry as defined by [RFC5785]:
+
+ URI suffix: openpgpkey
+
+ Change controller: IETF
+
+ Specification document: This
+
+7. Normative References
+
+ [RFC0822] Crocker, D., "STANDARD FOR THE FORMAT OF ARPA INTERNET
+ TEXT MESSAGES", STD 11, RFC 822, DOI 10.17487/RFC0822,
+ August 1982, <http://www.rfc-editor.org/info/rfc822>.
+
+ [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate
+ Requirement Levels", BCP 14, RFC 2119, March 1997.
+
+ [RFC3156] Elkins, M., Del Torto, D., Levien, R., and T. Roessler,
+ "MIME Security with OpenPGP", RFC 3156, August 2001.
+
+ [RFC4880] Callas, J., Donnerhacke, L., Finney, H., Shaw, D., and R.
+ Thayer, "OpenPGP Message Format", RFC 4880, November 2007.
+
+ [RFC5226] Narten, T. and H. Alvestrand, "Guidelines for Writing an
+ IANA Considerations Section in RFCs", BCP 26, RFC 5226,
+ May 2008.
+
+ [RFC5785] Nottingham, M. and E. Hammer-Lahav, "Defining Well-Known
+ Uniform Resource Identifiers (URIs)", RFC 5785, DOI
+ 10.17487/RFC5785, April 2010,
+ <http://www.rfc-editor.org/info/rfc5785>.
+
+ [RFC6189] Zimmermann, P., Johnston, A., Ed., and J. Callas, "ZRTP:
+ Media Path Key Agreement for Unicast Secure RTP", RFC
+ 6189, DOI 10.17487/RFC6189, April 2011,
+ <http://www.rfc-editor.org/info/rfc6189>.
+
+Appendix A. Test Vectors
+
+ For help implementing this specification a non-normative example is
+ given:
+
+
+
+
+
+Koch Expires November 7, 2016 [Page 9]
+
+Internet-Draft OpenPGP Web Key Service May 2016
+
+
+A.1. Sample key
+
+ TODO
+
+A.2. Software Notes
+
+ GnuPG supports the key discovery described in this document since
+ version 2.1.12. To use it, the new method "wkd" needs to be used
+ with the --auto-key-locate option.
+
+Appendix B. Changes
+
+ o This is the initial draft.
+
+B.1. TODO
+
+ o What about authenticated submission?
+
+ o Describe how to handle a key with several User IDs.
+
+Author's Address
+
+ Werner Koch
+ GnuPG Project
+
+ Email: wk at gnupg.org
+ URI: https://gnupg.org
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+Koch Expires November 7, 2016 [Page 10]
diff --git a/misc/id/openpgp-webkey-service/middle.mkd b/misc/id/openpgp-webkey-service/middle.mkd
new file mode 100644
index 0000000..3f0e63f
--- /dev/null
+++ b/misc/id/openpgp-webkey-service/middle.mkd
@@ -0,0 +1,336 @@
+# Introduction
+
+This memo describes a method to associate OpenPGP keys with a mail
+address and now to look them up using a web service with a well-known
+URI. In addition a mail based protocol is given to allow a client to
+setup such an association and to maintain it.
+
+# Notational Conventions
+
+The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
+"SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this
+document are to be interpreted as described in [](#RFC2119).
+
+
+# Web Key Directory
+
+A major use case for OpenPGP is the encryption of mail. A common
+difficulty of sending encrypted mails to a new communication partner is
+to find the appropriate public key of the recipient. Unless an
+off-channel key exchange has been done, there are no easy ways to
+discover the required key. The common practice is to search the
+network of public key servers for a key matching the recipient's mail
+address. This practise bears the problem that the keyservers are not
+able to give a positive confirmation that a key actually belongs to
+the mail addresses given in the key. Further, there are often several
+keys matching a mail address and thus one needs to pick a key on good
+luck. This is clearly not a secure way to setup an end-to-end
+encryption. Even if the need for a trusted key for an initial mail
+message is relinquished, a non-authenticated key may be a wrong one
+and the actual recipient would receive a mail which she can't decrypt,
+due to the use of a wrong key.
+
+Methods to overcome this problem are
+
+ - sending an initial unencrypted messages with the public key
+ attached,
+ - using the OpenPGP DANE protocol to lookup the recipients key via
+ the DNS.
+
+The first method has the obvious problems of not even trying to
+encrypt the initial mail, an extra mail round-trip, and problems with
+unattended key discovery.
+
+The latter method works fine but requires that mail providers need to
+set up a separate DNS resolver to provide the key. The administration
+of a DNS zone is often not in the hands of small mail installations.
+Thus an update of the DNS resource records needs to be delegated
+to the ISP running the DNS service. Further, DNS lookups are not
+encrypted and missing all confidentially. Even if the participating
+MUAs are using STARTTLS to encrypt the mail exchange, a DNS lookup for
+the key unnecessary identifies the local-part of the recipients mail
+address to any passive eavesdroppers.
+
+This memo specified a new method for key discovery using an encrypted
+https connection.
+
+## Key Discovery
+
+Although URIs are able to encode all kind of characters,
+straightforward implementations of a key directory may want to store
+the "local-part" of a mail address directly in the file system. This
+forbids the use of certain characters in the "local-part". To allow
+for such an implementation method the URI uses an encoded form of the
+"local-part" which can be directly mapped to a file name.
+
+OpenPGP defines its User IDs, and thus the mail address, as UTF-8
+strings. To help with the common pattern of using capitalized names
+(e.g. "Joe.Doe at example.org") for mail addresses, and under the premise
+that almost all MTAs treat the "local-part" case-insensitive and that
+the "domain-part" is required to be compared case-insensitive anyway,
+all upper-case ASCII characters in a User ID are mapped to lowercase.
+Non-ASCII characters are not changed.
+
+The so mapped "local-part" is hashed using the SHA-1 algorithm. The
+resulting 160 bit digest is encoded using the Z-Base-32 method as
+described in [](#RFC6189), section 5.1.6. The resulting string has a
+fixed length of 32 octets. To form the URI, the scheme "https://" is
+concatenated with the mapped "domain-part", the fixed string
+"./well-known/openpgpkey/hu/", the "domain-part" again, and the above
+constructed 32 octet string.
+
+For example the URI to lookup the key for Joe.Doe at Example.ORG is:
+
+ https://example.org/.well-known/openpgpkey/
+ hu/example.org/iy9q119eutrkn8s1mk4r39qejnbu3n5q
+
+(line has been wrapped for rendering purposes)
+
+The HTTP GET method MUST return the binary representation of the
+OpenPGP key for the given mail address. The key needs to carry a User
+ID packet ([](#RFC4880)) with that mail address. Note that the key
+may be revoked or expired - it is up to the client to handle such
+conditions. The server MUST also accept a HEAD method so that a
+client may only check for the existence of a key.
+
+The server SHOULD return "application/pgp-key" as the content-type for
+the data but clients MUST also accept "application/octet-string" as
+content-type. The server MUST NOT return an ASCII armored version of
+the key.
+
+
+# Web Key Directory Update Protocol
+
+To put keys into the key directory a protocol to automate the task is
+desirable. The protocol defined here is entirely based on mail and
+the assumption that a mail provider can securely deliver mail to the
+INBOX of a user (e.g. an IMAP folder). Note that the same protocol
+may also be used for submitting keys for use with OpenPGP DANE.
+
+We assume that the user already created a key for her mail account
+alice at example.org. To install the key at her provider's Web Key
+Directory, she performs the following steps:
+
+1. She retrieves a file which contains one line with the mail address
+ used to submit the key to the mail provider. See below for the
+ syntax of that file. For a mail address at the domain "example.org"
+ the URI of the file is
+
+ https://example.org/.well-known/openpgpkey/submission-address
+
+2. She sends her key using SMTP (or any other transport mechanism) to
+ the provider using the submission address. The content-type SHOULD
+ be "application/pgp-key" and the key being a binary attachment
+ (which is then likely base64 encoded). Note that the OpenPGP ASCII
+ armor is not used.
+
+3. The provider checks that the received key has a User ID which
+ - matches an account name of the provider,
+ - and that the from address matches that account.
+
+4. The provider sends an encrypted message containing a nonce and the
+ fingerprint of the key to the mail account of the user. Note that
+ a similar scheme is used by the well known caff(1) tool to
+ help with key signing parties.
+
+5. A legitimate user will be able to decrypt the message because she
+ created the key and is in charge of the private key. This step
+ verifies that the submitted key has actually been created by the
+ owner of the account.
+
+6. The user sends the decrypted nonce back to the submission address
+ as a confirmation that the private key is owned by her and that the
+ provider may now publish the key. Also technically not required,
+ it is suggested that the mail to the provider is encrypted. The
+ public key for this is retrieved using the key lookup protocol
+ described above.
+
+7. The provider receives the nonce, matches it with its database of
+ pending confirmations and then publishes the key. Finally the
+ provider sends a mail back to the user to notify her of the
+ the publication of her key.
+
+The message data structures used for the above protocol are specified
+in detail below. In the following sections the string "WELLKNOWN"
+denotes the first part of an URI specific for a domain. In the
+examples the domain "example.org" is assumed, thus
+
+ WELLKNOWN := https://example.org/.well-known/openpgpkey
+
+The term "target key" denotes the to be published key, the term
+"submission key" the key associated with the submission-address of the
+mail provider.
+
+## The Submission Address
+
+The address of the submission file is
+
+ WELLKNOWN/submission-address
+
+The file consists of exactly one line, terminated by a LF, or the
+sequence of CR and LF, with the full mail address to be used for
+submission of a key to the mail provider. For example the content of
+the file may be
+
+ key-submission-example.org at directory.example.org
+
+## The Submission Mail
+
+The mail used to submit a key to the mail provider MUST comply to the
+PGP/MIME specification ([](#RFC3156), section 7), which states that the
+Content-Type must be "application/pgp-keys", there are no required or
+optional parameters, and the body part contains the ASCII-armored
+transferable Public Key Packets as defined in [](#RFC4880),
+section 11.1.
+
+If the mail provider has published an encryption key for the
+submission-address in the Web Key Directory, the key to be published
+MUST be submitted using a PGP/MIME encrypted message ([](#RFC3156),
+section 4). The message MUST not be signed (because the
+authenticity of the signing key has not yet been confirmed). After
+decryption of the message at the mail provider a single
+"application/pgp-keys" part, as specified above, is expected.
+
+## The Confirmation Request
+
+The mail provider sends a confirmation mail in response to a received
+key publication request. The message SHOULD be sent from the
+submission-address of the mail provider to the mail address extracted
+from the target key. The message needs to be encrypted to the target
+key and MAY be signed by the submission key. PGP/MIME MUST be used
+for encryption and signing; the Combined method ([](#RFC3156),
+section 6.2) MUST be used if the message is to be signed.
+
+The Content-type used for the plaintext part MUST be
+"application/vnd.gnupg.wkd". The body consists of name-value pairs
+with one name-value pair per LF or CR+LF terminated line. Empty lines
+are allowed and will be ignored by the receiver. A colon is used to
+terminate a name.
+
+In a confirmation request the following names MUST be send in the
+specified order:
+
+"type"
+ : The value must be "confirmation-request".
+
+"from"
+ : This is the mailbox the user is expected to sent the confirmation
+ response to. The value must match the mailbox part of the
+ "From:" address of this request.
+
+"address"
+ : The value is the addr-spec part of the target key's mail address.
+ The value SHOULD match the addr-spec part of the recipient's
+ address. The value MUST be be UTF-8 encoded as required for an
+ OpenPGP User ID.
+
+"fingerprint"
+ : The value is the fingerprint of the target key. The fingerprint
+ is given in uppercase hex encoding without any interleaving
+ spaces.
+
+"nonce"
+ : The value is a string with a minimum length of 16 octets and a
+ maximum length of 64 octets. The string must entirely be made up
+ of random ASCII letters or digits. This nonce will be sent back
+ to the mail provider as proof that the recipient is the legitimate
+ owner of the target-key.
+
+
+The receiver of the message decrypts the message, checks that the
+"fingerprint" matches the target key, checks that the "address"
+matches a User ID of the target key, and checks the other constrains
+of the request format. If any constraint is not asserted, or the
+fingerprint or User ID do not match the target key, or there is no
+pending publication requests (i.e. a mail recently sent o the
+submission address), the user MAY be notified about this fake
+confirmation attempt.
+
+In other cases the confirmation request is legitimate and the MUA
+shall silently send a response as described in the next section.
+
+## The Confirmation Response
+
+A response to a confirmation request MUST only be send in the positive
+case; there is no negative confirmation response. A mail service
+provider is expected to cancel a pending key submission after a
+suitable time without a confirmation. The mail service provider
+SHOULD not retry the sending of a confirmation request after the first
+request has been send successfully.
+
+The user MUST send the confirmation response from her target mail
+address to the "from" address of the confirmation request. The
+message MUST be signed and SHOULD be encrypted. The PGP/MIME Combined
+format MUST be used for encryption and signing ([](#RFC3156),
+section 6.2). The encryption key can be taken from the Web Key
+Directory.
+
+The Content-type used for the plaintext message MUST also be
+"application/vnd.gnupg.wkd". The format is the same as described
+above for the Confirmation Request. The body must contain three
+name-value pairs in this order:
+
+"type"
+ : The value must be "confirmation-response".
+
+"from"
+ : The value must match the mailbox part of the "From:" address of
+ this response.
+
+"nonce"
+ : The value is the value of the "nonce" parameter from the
+ confirmation request.
+
+
+## Policy Flags
+
+For key generation and submission it is sometimes useful to tell the
+client about certain properties of the mail provider in advance. This
+can be done with a file at the URL
+
+ WELLKNOWN/policy
+
+The file contains keywords, one per line with each line terminated by
+a LF or the sequence of CR and LF. Empty lines and lines starting
+with a '#' character are considered comment lines. A keyword is made
+up of lowercase letters, digits, hyphens, or dots. An underscore is
+allowed as a name space delimiters; see below. The first character
+must be a letter. Clients MUST use case-insensitive matching.
+
+Currently defined keywords are:
+
+"mailbox-only"
+ : The mail server provider does only accept keys with only a mailbox
+ in the User ID. In particular User IDs with a real name in
+ addition to the mailbox will be rejected as invalid.
+
+More keywords will be defined in updates to this I-D. There is no
+registry yet except for this document. For experimental use of new
+features or for provider specific settings, keywords MUST be prefixed
+with a domain name and an underscore.
+
+
+# Security Considerations
+
+The use of SHA-1 for the mapping of the "local-part" to a fixed string
+is not a security feature but merely used to map the local-part to a
+fixed-sized string made from a well defined set of characters. It is
+not intended to conceal information about a mail address.
+
+The domain name part of the mail address is not part of the hash to
+avoid problems with internationalized domain names. Instead a
+separate web service is required for each domain name.
+
+
+# IANA Considerations
+
+## Well-Known URI
+
+IANA is requested to assign a well-known URI in the "Well-Known URIs"
+registry as defined by [](#RFC5785):
+
+ URI suffix: openpgpkey
+
+ Change controller: IETF
+
+ Specification document: This
diff --git a/misc/id/openpgp-webkey-service/template.xml b/misc/id/openpgp-webkey-service/template.xml
new file mode 100644
index 0000000..c14ef88
--- /dev/null
+++ b/misc/id/openpgp-webkey-service/template.xml
@@ -0,0 +1,61 @@
+<?xml version="1.0" ?>
+<!DOCTYPE rfc SYSTEM 'rfc2629.dtd' [
+ <!ENTITY pandocAbstract PUBLIC '' 'abstract.xml'>
+ <!ENTITY pandocMiddle PUBLIC '' 'middle.xml'>
+ <!ENTITY pandocBack PUBLIC '' 'back.xml'>
+ <!ENTITY rfc.0822 PUBLIC '' '../common/reference.RFC.0822.xml'>
+ <!ENTITY rfc.2119 PUBLIC '' '../common/reference.RFC.2119.xml'>
+ <!ENTITY rfc.3156 PUBLIC '' '../common/reference.RFC.3156.xml'>
+ <!ENTITY rfc.4880 PUBLIC '' '../common/reference.RFC.4880.xml'>
+ <!ENTITY rfc.5226 PUBLIC '' '../common/reference.RFC.5226.xml'>
+ <!ENTITY rfc.5785 PUBLIC '' '../common/reference.RFC.5785.xml'>
+ <!ENTITY rfc.6189 PUBLIC '' '../common/reference.RFC.6189.xml'>
+]>
+
+<rfc ipr="trust200902" category="info"
+ docName="draft-koch-openpgp-webkey-service-00">
+
+<?rfc toc="yes"?>
+<?rfc symrefs="yes"?>
+<?rfc sortrefs="yes"?>
+<?rfc subcompact="no"?>
+<?rfc compact="yes"?>
+<?rfc comments="yes"?>
+
+
+ <front>
+ <title>OpenPGP Web Key Service</title>
+ <author initials="W." surname="Koch"
+ fullname="Werner Koch">
+ <organization>GnuPG Project</organization>
+ <address>
+ <email>wk at gnupg.org</email>
+ <uri>https://gnupg.org</uri>
+ </address>
+ </author>
+
+ <date month="May" year="2016" />
+ <area>Security</area>
+
+ <abstract>
+ &pandocAbstract;
+ </abstract>
+ </front>
+
+ <middle>
+ &pandocMiddle;
+ </middle>
+
+ <back>
+ <references title="Normative References">
+ &rfc.2119;
+ &rfc.3156;
+ &rfc.4880;
+ &rfc.5226;
+ &rfc.5785;
+ &rfc.0822;
+ &rfc.6189;
+ </references>
+ &pandocBack;
+ </back>
+</rfc>
-----------------------------------------------------------------------
Summary of changes:
misc/id/openpgp-webkey-service/abstract.mkd | 4 +
misc/id/openpgp-webkey-service/back.mkd | 23 +
.../draft-koch-openpgp-webkey-service-00.txt | 560 +++++++++++++++++++++
misc/id/openpgp-webkey-service/middle.mkd | 336 +++++++++++++
.../template.xml | 35 +-
5 files changed, 938 insertions(+), 20 deletions(-)
create mode 100644 misc/id/openpgp-webkey-service/abstract.mkd
create mode 100644 misc/id/openpgp-webkey-service/back.mkd
create mode 100644 misc/id/openpgp-webkey-service/draft-koch-openpgp-webkey-service-00.txt
create mode 100644 misc/id/openpgp-webkey-service/middle.mkd
copy misc/id/{eddsa-for-openpgp => openpgp-webkey-service}/template.xml (57%)
hooks/post-receive
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