So a warrant is required to seize an email as it travels from sender to receiver.

FORBES: That EU Privacy Directive? It's a Gag-order Killer Too

Corvis is developing new technology that uses only flashes of light to transmit data from sender to receiver.

FORBES: Corvis' IPO

The MIT mathematicians, that is, sidestepped a weak spot that had plagued cryptographers ever since the days of the ancient Greeks: How do sender and receiver hand off a key without risking that their communication channel or their courier will be compromised in some way?

FORBES: I've got a secret