11.1 Send requests via WKS

The gpg-wks-client is used to send requests to a Web Key Service provider. This is usually done to upload a key into a Web Key Directory.

With the --supported command the caller can test whether a site supports the Web Key Service. The argument is an arbitrary address in the to be tested domain. For example foo@example.net. The command returns success if the Web Key Service is supported. The operation is silent; to get diagnostic output use the option --verbose. See option --with-colons for a variant of this command.

With the --check command the caller can test whether a key exists for a supplied mail address. The command returns success if a key is available.

The --create command is used to send a request for publication in the Web Key Directory. The arguments are the fingerprint of the key and the user id to publish. The output from the command is a properly formatted mail with all standard headers. This mail can be fed to sendmail(8) or any other tool to actually send that mail. If sendmail(8) is installed the option --send can be used to directly send the created request. If the provider request a ’mailbox-only’ user id and no such user id is found, gpg-wks-client will try an additional user id.

The --receive and --read commands are used to process confirmation mails as send from the service provider. The former expects an encrypted MIME messages, the latter an already decrypted MIME message. The result of these commands are another mail which can be send in the same way as the mail created with --create.

The command --install-key manually installs a key into a local directory (see option -C) reflecting the structure of a WKD. The arguments are a file with the keyblock and the user-id to install. If the first argument resembles a fingerprint the key is taken from the current keyring; to force the use of a file, prefix the first argument with "./". If no arguments are given the parameters are read from stdin; the expected format are lines with the fingerprint and the mailbox separated by a space. The command --remove-key removes a key from that directory, its only argument is a user-id.

The command --mirror is similar to --install-key but takes the keys from the the LDAP server configured for Dirmngr. If no arguments are given all keys and user ids are installed. If arguments are given they are taken as domain names to limit the to be installed keys. The option --blacklist may be used to further limit the to be installed keys.

The command --print-wkd-hash prints the WKD user-id identifiers and the corresponding mailboxes from the user-ids given on the command line or via stdin (one user-id per line).

The command --print-wkd-url prints the URLs used to fetch the key for the given user-ids from WKD. The meanwhile preferred format with sub-domains is used here.

All commands may also be given without the two leading dashes.

gpg-wks-client understands these options:

--send

Directly send created mails using the sendmail command. Requires installation of that command.

--with-colons

This option has currently only an effect on the --supported command. If it is used all arguments on the command line are taken as domain names and tested for WKD support. The output format is one line per domain with colon delimited fields. The currently specified fields are (future versions may specify additional fields):

1 - domain

This is the domain name. Although quoting is not required for valid domain names this field is specified to be quoted in standard C manner.

2 - WKD

If the value is true the domain supports the Web Key Directory.

3 - WKS

If the value is true the domain supports the Web Key Service protocol to upload keys to the directory.

4 - error-code

This may contain an gpg-error code to describe certain failures. Use ‘gpg-error CODE’ to explain the code.

5 - protocol-version

The minimum protocol version supported by the server.

6 - auth-submit

The auth-submit flag from the policy file of the server.

7 - mailbox-only

The mailbox-only flag from the policy file of the server.

--output file

-o

Write the created mail to file instead of stdout. Note that the value - for file is the same as writing to stdout. If this option is used with the --check command and a key was found it is written to the given file.

--status-fd n

Write special status strings to the file descriptor n. This program returns only the status messages SUCCESS or FAILURE which are helpful when the caller uses a double fork approach and can’t easily get the return code of the process.

-C dir

--directory dir

Use dir as top level directory for the commands --mirror, --install-key and --remove-key. The default is openpgpkey.

--blacklist file

This option is used to exclude certain mail addresses from a mirror operation. The format of file is one mail address (just the addrspec, e.g. "postel@isi.edu") per line. Empty lines and lines starting with a ’#’ are ignored.

--add-revocs

--no-add-revocs

If enabled append revocation certificates for the same addrspec as used in the WKD to the key. Modern gpg version are able to import and apply them for existing keys. Note that when used with the --mirror command the revocation are searched in the local keyring and not in an LDAP directory. The default is --add-revocs.

--verbose

Enable extra informational output.

--quiet

Disable almost all informational output.

--version

Print version of the program and exit.

--help

Display a brief help page and exit.

Examples

To use the services with clients lacking integrated support, the mailcap mechanism can be used. Simply put:

application/vnd.gnupg.wks; \
  /usr/local/bin/gpg-wks-client -v --read --send; \
  needsterminal; \
  description=WKS message

into the /etc/mailcap. This assumes that a /usr/lib/sendmail is installed. With this configuration any real mail programs will run gpg-wks-client for messages received from a Web Key Service.