Key establishment question

In Internet, when two computers need to establish a secret key, the two
machines need to exchange two random numbers, e.g., R1, R2, if
Diffie-Hellman is used. How are the two random numbers exchanged? Are
the two numbers sent as TCP/IP packets? How is Diffie-Hellman
implemented in Internet? Thanks a lot.

Jack

Re: Key establishment question

Jack wrote:
> In Internet, when two computers need to establish a secret key, the two
> machines need to exchange two random numbers, e.g., R1, R2, if
> Diffie-Hellman is used. How are the two random numbers exchanged? Are
> the two numbers sent as TCP/IP packets? How is Diffie-Hellman
> implemented in Internet? Thanks a lot.
>
> Jack
>

Generally by means of a public-key algorithm. I encrypt the number
with your public key, and only a person who holds the corresponding
private key (presumably, only you) can decrypt it. Actually, I also
encrypt it with my private key. The fact that my public key decrypts
it proves that only I could have encrypted it.


Chris Mattern

Re: Key establishment question

Chris Mattern wrote:
> Jack wrote:
> > In Internet, when two computers need to establish a secret key, the two
> > machines need to exchange two random numbers, e.g., R1, R2, if
> > Diffie-Hellman is used. How are the two random numbers exchanged? Are
> > the two numbers sent as TCP/IP packets? How is Diffie-Hellman
> > implemented in Internet? Thanks a lot.
> >
> > Jack
> >

Thanks.
> Generally by means of a public-key algorithm. I encrypt the number
> with your public key, and only a person who holds the corresponding
> private key (presumably, only you) can decrypt it. Actually, I also
> encrypt it with my private key. The fact that my public key decrypts
> it proves that only I could have encrypted it.
>
Then the public key encrypted random numbers are sent as TCP/IP
packets?
I know the mechanism of Diffie-Hellman. My question is how
Diffie-Hellman is implemented in Internet.

Jack

Re: Key establishment question

Jack wrote:

> I know the mechanism of Diffie-Hellman. My question is how
> Diffie-Hellman is implemented in Internet.

Internet is a network, no protocol. So which protocol are your referring to?

Re: Key establishment question

Thanks.
>
> > I know the mechanism of Diffie-Hellman. My question is how
> > Diffie-Hellman is implemented in Internet.
>
> Internet is a network, no protocol. So which protocol are your referring to?

Such as https, scp.
Thanks

Re: Key establishment question

In article <1155394417.099599.276400@m79g2000cwm.googlegroups.com>,
"Jack" wrote:

> Thanks.
> >
> > > I know the mechanism of Diffie-Hellman. My question is how
> > > Diffie-Hellman is implemented in Internet.
> >
> > Internet is a network, no protocol. So which protocol are your referring to?
>
> Such as https, scp.
> Thanks

There isn't a separate mechanism used for exchanging keys, it's just
something that's incorporated into whatever protocol needs to make use
of it. HTTPS makes use the SSL protocol to do key exchange, certificate
checking, and encrypted communication.

--
Barry Margolin, barmar@alum.mit.edu
Arlington, MA
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