On 3/17/21 8:17 PM, Viktor Dukhovni wrote:
On Wed, Mar 17, 2021 at 07:44:05PM -0400, Robert Moskowitz wrote:
I have created my X25519 pub/priv keypair with:
openssl genpkey -algorithm X25519\
-out $dir/private/$clientemail-X.key.$format
Are you sure you didn't want ed25519 instead? X25519 is a key agreement
menthod, not a signature method.
My limited understanding is that for encrypted S/MIME, and ECDH cert
is needed. Thus if ED25519 is used for signing said S/MIME, X25519 is
used for encrypting.
I see, this is for CMS, so you're trying to support:
https://tools.ietf.org/html/draft-ietf-curdle-cms-ecdh-new-curves-10
openssl req -config $dir/openssl-intermediate.cnf\
-key $dir/private/$clientemail-X.key.$format \
-subj "$DN" -new -out $dir/csr/$clientemail-X.csr.$format
which is what I used for ED25519 client certs. But I get an error:
140487683954496:error:0608D096:digital envelope
routines:EVP_PKEY_sign_init:operation not supported for this
keytype:crypto/evp/pmeth_fn.c:39:
Not surprising, why do you expect this to work?
Shooting from the hip, a bit. If I am going to have an X25519 cert,
then I need a csr and this is the command to make one. So try it and
see what it does. Not too well, it turns out.
Well, CSRs are self-signed, and X25519 does not support signing, so
you CANNOT have an X25519 CSR.
Slap myself on the forehead....
Of course I know that. But did not stop to think this through. :(
Will read through all this and get back here....
You can however create an X25519
certificate directly for a given key:
https://crypto.stackexchange.com/questions/19452/static-dh-static-ecdh-certificate-using-openssl
with other details (names, extensions, ...) pulled from a CSR.
What can't get is proof of posession.
Oh, and I am ASSuMEing that a CA cert of ED25519 signs an X25519 client
cert. Haven't found instructions on this, but it seems reasonable...
https://crypto.stackexchange.com/questions/27866/why-curve25519-for-encryption-but-ed25519-for-signatures
Well the CA can use any algorithm that supports signing, and is widely
supported. It does not have to be Ed25519.
