849e3a5949
We'll now parse the response messages on the client side, abort after a previously defined timeout and trigger the LUKS unlocking process, if requested (although the latter isn't fully implemented yet).
36 lines
1.7 KiB
Markdown
36 lines
1.7 KiB
Markdown
# luksrku
|
|
luksrku is a tool that allows you to remotely unlock LUKS disks during bootup
|
|
from within your initrd. The intention is to have full-disk-encryption with
|
|
LUKS-rootfs running headlessly. You should be able to remotely unlock their
|
|
LUKS cryptographic file systems when you know they have been (legitimately)
|
|
rebooted.
|
|
|
|
This works as follows: The luksrku client (which needs unlocking) and luksrku
|
|
server (which holds all the LUKS keys) share a secret. The client either knows
|
|
the address of the server or it can issue a broadcast in the network to find
|
|
the correct one. With the help of the shared secret, a TLS connection is
|
|
established betweem the client and a legitimate server (who also knows the same
|
|
secret). The server then tells the client all the LUKS passphrases, which
|
|
performs luksOpen on all volumes.
|
|
|
|
## Security
|
|
luksrku uses TLSv1.3-PSK with forward-secrecy key shares (i.e., ECDHE). The
|
|
curves that are used are X448 and X25519 for key agreement and
|
|
TLS_CHACHA20_POLY1305_SHA256 or TLS_AES_256_GCM_SHA384 as cipher suites. PSKs
|
|
are 256 bit long and randomly generated (/dev/urandom). Likewise, the LUKS
|
|
passphrases are based on 256 bit long secrets and are converted to Base64 for
|
|
easier handling (when setting up everything initially).
|
|
|
|
The binary protocol that runs between both is intentionally extremely simple to
|
|
allow for easy code review. It exclusively uses fixed message lengths.
|
|
|
|
The key database is encrypted itself, using AES256-GCM, a 128 bit randomized
|
|
initialization vector and authenticated with a 128 bit authentication tag. Key
|
|
derivation is done using scrypt with N = 131072 = 2^18, r = 8, p = 1.
|
|
|
|
## Dependencies
|
|
OpenSSL v1.1 is required for luksrku.
|
|
|
|
## Example
|
|
TODO
|