clevis-encrypt-tang man page

clevis-encrypt-tang — Encrypts using a Tang binding server policy

Synopsis

clevis encrypt tang Config PT JWE

Overview

The clevis encrypt tang command encrypts using a Tang binding server policy. Its only argument is the JSON configuration object.

Clevis provides support for the Tang network binding server. Tang provides a stateless, lightweight alternative to escrows. Encrypting data using the Tang pin works like this:

$ clevis encrypt tang ´{"url":"http://tang.srv"}´ < PT > JWE
The advertisement contains the following signing keys:

_OsIk0T-E2l6qjfdDiwVmidoZjA

Do you wish to trust these keys? [ynYN] y

To decrypt the data, just pass it to the clevis decrypt command:

$ clevis decrypt < JWE > PT

As you can see above, Tang utilizes a trust-on-first-use workflow. If you already know the thumbprint of a trusted key, you can specify it in the configuration at encryption time:

$ cfg=´{"url":"http://tang.srv","thp":"_OsIk0T-E2l6qjfdDiwVmidoZjA"}´
$ clevis encrypt tang "$cfg" < PT > JWE

Obtaining the thumbprint of a trusted signing key is easy. If you have access to the Tang server´s database directory, simply do:

$ jose jwk thp -i $DBDIR/$SIG.jwk

Tang can also perform entirely offline encryption if you pre-share the server advertisment. You can fetch the advertisment with a simple command (just be careful your network isn´t compromised!):

$ curl -f $URL/adv > adv.jws

Once you have the advertisment file, just provide it:

$ clevis encrypt tang ´{"url":...,"adv":"adv.jws"}´ < PT > JWE

Config

This command uses the following configuration properties:

url (string)

The base URL of the Tang server (REQUIRED)

thp (string)

The thumbprint of a trusted signing key

adv (string)

A filename containing a trusted advertisement

adv (object)

A trusted advertisement (raw JSON)

Author

Nathaniel McCallum <npmccallum@redhat.com>

See Also

clevis-decrypt(1)

Referenced By

clevis(1), clevis-bind-luks(1), clevis-encrypt-sss(1).

June 2017