commit d441108c6f77541bb66fcd5b3389415b4c232008
author David Howells <dhowells@redhat.com> Wed Sep 26 10:09:51 2012 +0100
committer Rusty Russell <rusty@rustcorp.com.au> Wed Oct 10 20:01:21 2012 +1030
tree eda7f0ed11d134b992bcb085a4543d63f38def4b
parent ea0b6dcf71d216dc11733ac19b26df0f5d0fd6c2

MODSIGN: Automatically generate module signing keys if missing

Automatically generate keys for module signing if they're absent so that
allyesconfig doesn't break.  The builder should consider generating their own
key and certificate, however, so that the keys are appropriately named.

The private key for the module signer should be placed in signing_key.priv
(unencrypted!) and the public key in an X.509 certificate as signing_key.x509.

If a transient key is desired for signing the modules, a config file for
'openssl req' can be placed in x509.genkey, looking something like the
following:

	[ req ]
	default_bits = 4096
	distinguished_name = req_distinguished_name
	prompt = no
	x509_extensions = myexts

	[ req_distinguished_name ]
	O = Magarathea
	CN = Glacier signing key
	emailAddress = slartibartfast@magrathea.h2g2

	[ myexts ]
	basicConstraints=critical,CA:FALSE
	keyUsage=digitalSignature
	subjectKeyIdentifier=hash
	authorityKeyIdentifier=hash

The build process will use this to configure:

	openssl req -new -nodes -utf8 -sha1 -days 36500 -batch \
		-x509 -config x509.genkey \
		-outform DER -out signing_key.x509 \
		-keyout signing_key.priv

to generate the key.

Note that it is required that the X.509 certificate have a subjectKeyIdentifier
and an authorityKeyIdentifier.  Without those, the certificate will be
rejected.  These can be used to check the validity of a certificate.

Note that 'make distclean' will remove signing_key.{priv,x509} and x509.genkey,
whether or not they were generated automatically.

Signed-off-by: David Howells <dhowells@redhat.com>
Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>