Expand OpenVPN data key usage

[schwabe]

No description provided.

[reynir]

This is a bit ambiguous. It is unclear what key-id will be used. For example:

• Key id is 0
• Renegotiation attempt! Let's us key id 1.
• Oh no, it failed! So we continue with key id 0
• Retry renegotiation. We don't increment the key id. So is it 0 or 1? 0 because previous reneg failed so we don't increment. But oh no! We probably meant for it to be 1?!

[reynir]

Maybe this?

Suggested change

	key-id. If a renegotiation fails and is reattempted, the key-id
	will not be increased. Only the intial TLS session will use the key-id
	key-id. If a renegotiation fails and is reattempted, the key-id
	from the failed attempt will be reused. Only the intial TLS session will use the key-id

[reynir]

I am guessing this is a typo

Suggested change

	set by the --hand-window and --renog-sec options, which default to 60 and 3600
	set by the --hand-window and --reneg-sec options, which default to 60 and 3600

[reynir]

What if renegotiation_time is 1? :D Is this then half a second? I ask because I use --reneg-sec 1 in a test setup, and I am curious if sub second values are used.

[schwabe]

Then the implementation becomes broken and directly uses the new key since 1/2 = 0 in integer math:

From ssl.c:

static int
auth_deferred_expire_window(const struct tls_options *o)
{
    int ret = o->handshake_window;
    const int r2 = o->renegotiate_seconds / 2;

    if (o->renegotiate_seconds && r2 < ret)
    {
        ret = r2;
    }
    return ret;
}

I didn't want to include this that are more implementation bugs in corner cases into the RFC.

[reynir]

Ok, that makes sense. Thanks for the code snippet. I'll modify my test setup!