Once you have created an initial network of contacts around your secushare identities, it gets easy to just adopt further people from your contacts' common friends. secushare can even suggest such contacts to you, as in "This is Linda. You have 11 contacts in common. (ADD)". This is most likely the most frequent way to expand your cryptographic neighborhood - just click on the ADD button.

Another approach is to have contact information printed in form of a QR-Code on the business card. Your grandfather will be able to hold that code in front of his webcam and poof, a cryptographically safe connection is established to you.

This is also the vehicle for business on secushare: You just print your company's contact information on your brochures and advertisements. No more risk of (foreign) governmental man in the middle, since doing a man in the middle attack on printed paper is more complicated and doesn't scale as well.

Bluetooth, Infrared, WiFi… whichever way two devices running secushare can find each other in the radio neighborhood could enable their owners to engage in an exchange of cryptographic contact information without much further ado. Just look at both screens and make sure they are showing the same graphic.

ZRTP provides a similar method for users of audio/video telephony tools to ensure their connection has no men in the middle by displaying a code to the participants which they should read to each other aloud to ensure they are seeing the same code.

There are cryptographic possibilities to establish a first secure channel between two people who know each other in real life by means of a shared secret, like a passphrase you exchange over a beer, then later use when connecting online.

OTR pioneered this method, calling it the "Socialist Millionaire Protocol."

Once the channel is established, each other's public keys can be exchanged, peer lists can be subscribed and they can start looking for further common friends to add.