[dpenning]

I'm not sure if you understood what MITM(man in the middle attacks) actually means.

I will give you a high level example of what he is talking about. your software displays a public key to perform encryption. what 'the NSA' can do is put a proxy (or use your isp) in between you and the person you are sending data to. Then they can pose as the person you are sending data to by hosting their own public key to both you and the person you want to send data to. now they can decrypt information that you send, and then encrypt it with their private key and send it to the other person. NOW THE NSA CAN SPY ON YOU USING YOUR APP.

man in the middle attacks can get much more complex than that, but this should help you understand what is going on.

If you are attempting to write security software you should really at least learn crypto AND networking. it seems like you have not accomplished either of these.

[syjer]

If I understood their code/doc, the public keys must be exchanged out of band.

So how could the proxy pass for another person?

[dpenning]

I'm not sure what you mean by out of band

If you mean that it is communicated over TCP/IP(what i gathered from reading the doc), what is stopping someone who has access to whatever is connected to your IP from redirecting traffic to that port in order to do what was already discussed.

if you mean that it is shared in person off the internet, then what is the point of this program. Diffe Hellman, ECC, zero Knowledge proofs are all dependent on the discrete log problem being hard, so you might as well just start broadcasting to their ip with the key that they gave you in person instead of going through the trouble(and increase in vulnerability) of trying to establish that the person is who they say they are. maybe I'm wrong but I don't think that math is wrong.

in any case, I feel like the problem for this program stems from the fact that validating the IP address of the person is much more complicated than it seems. Its pretty much the reason centralized databases are needed for connections between people(those are bad things in our world now).

this is pretty much what is needed for this http://en.wikipedia.org/wiki/Web_of_trust

[hepek]

I wonder if the pubkeys could be maintained in a system such as namecoin? [never used namecoin, but it sounds right]