Two Dumb Questions

[Dag-Erling Smørgrav]

RW <rwmaillists at googlemail.com> writes:
> There's a simple paint analogy here:
>
>  https://en.wikipedia.org/wiki/Diffie–Hellman_key_exchange
>
> that illustrates how it's possible to exchange a shared secret without
> an eavesdropper knowing what it is. The shared secret can then be used
> for symmetric encryption using something like AES.

SSL / TLS didn't commonly use DH, much less *safe* DH, until fairly
recently, and DH alone is not very useful.  You need either a shared
secret or trusted key pairs to authenticate either or both endpoints.

> Actual protocols use public key cryptography so it can be established
> that the exchange is end to end, and not broken into two separate
> exchanges.

Assuming you can trust the public key, which is what CAs are for, but
CAs can be hacked, deceived or coerced.

DES
-- 
Dag-Erling Smørgrav - des at des.no