Two Dumb Questions

Dag-Erling Smørgrav des at
Mon Sep 26 20:48:16 UTC 2016

RW <rwmaillists at> writes:
> There's a simple paint analogy here:
> 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.

Dag-Erling Smørgrav - des at

More information about the freebsd-security mailing list