[guardian-dev] gibberbot, OTR, xmpp, android in general

[shmick at riseup.net]

thanks to all who replied

just finally, if i continue to use the older version does that mean i
should shop around for an xmpp server/provider that *does* enforce
cipher preferences (which will overide the weak android/java defaults)
*and* one that uses stronger suites preferentially, ideally those of PFS ?

with these 2 layers, being the context (xmpp) and content (otr) as lee
mentioned, which cipher suites are chosen for each layer and are they
even the same, or different ?

is it like this:

contact xmpp server - client hello
server response - server hello
initiate tls - xyz cipher suite
logged in - all aok
start sending msgs to contact on same server/provider - otr - abc cipher
suite



shmick at riseup.net:
> hello all,
> 
> i have a lot of things floating around that im really unable to answer
> critically without the required level of knowledge
> 
> essentially, i make use of your fantastic gibberbot 0.0.11-RC5 (i
> currently can't update to chat secure due to phone storage) and chat
> connected to jabber.ccc.de [1] as an example
> 
> packet traces show that gibberbot presents 35 cipher suites to offer and
> eventually my session is secured with TLS_RSA_WITH_RC4_128_MD5; an SSLv3
> suite
> 
> what i can say is that if my browser was using this suite over 'https'
> it would generally be accepted as insecure but i just don't know enough
> about jabber/xmpp et al to say when using 'OTR' whether it would be safe
> 
> does OTR always use forward secrecy and is this suite safe even though
> it's RC4 with MD5 ? i can only surmise that since the negotiated suite
> is not an ECDHE, DHE or EDH one then how would forward secrecy occur ?
> 
> why does gibberbot even need to offer RC4_40, DES40 and empty negotiation ?
> 
> i read [2] once that android and the underlying java sub system overides
> all the cipher suites 'iff' the client is not coded/created in a way
> that presents its own preferences
> 
> so i assume gibberbot does not override the android and java default
> insecure protocols or are there improvements in chatsecure ?
> 
> how could this have even been approved into android (out comes the tin
> foil hat; not taking it off just yet)
> 
> [1] http://xmpp.net/result.php?domain=jabber.ccc.de&type=client
> [2] http://op-co.de/blog/posts/android_ssl_downgrade/
> 
> 
> 
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