Expand OpenVPN data key usage #6
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openvpn-wire-protocol.xml
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| 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 |
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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?!
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Maybe this?
| 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 |
openvpn-wire-protocol.xml
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| <artwork> | ||
| min(handshake_window, renegotiation_time/2) | ||
| </artwork> | ||
| set by the --hand-window and --renog-sec options, which default to 60 and 3600 |
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I am guessing this is a typo
| 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 |
| In the default configuration of OpenVPN, the time period of promoting a key from | ||
| pending to active is calucated as | ||
| <artwork> | ||
| min(handshake_window, renegotiation_time/2) |
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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.
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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.
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Ok, that makes sense. Thanks for the code snippet. I'll modify my test setup!
Signed-off-by: Arne Schwabe <[email protected]>
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