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 advertisement. You can fetch the advertisement with a simple command (just be careful your network isn't compromised!):

$ curl -f $URL/adv > adv.jws

Once you have the advertisement file, just provide it:

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

Config

This command uses the following configuration properties:

See Also

clevis-decrypt(1)

Authors

Nathaniel McCallum <npmccallum@redhat.com>.

Referenced By

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

September 2017