After that case in which Brazilian government arrested a Facebook VP due to end-to-end encryption and no server storage of messages on WhatsApp to prove connection with a drug case, it's become pretty common for friends of mine to start conversations about what cryptography is and why we should use it on a daily basis. The same applies with the iPhone terrorist encryption case in which the FBI broke in.
For non-techie friends, it's easy to understand the basics of cryptography. I have managed to explain them the basics, public key x private key, what is end-to-end encryption during communication(your data is not stored encrypted, but it is "scrambled" during data exchange), all the core concepts without enter on more technical words like AES, MD5, SSL, PGP, hardware encryption acceleration, TPMs, etc. They like to have encryption on their phones, but they always come up with the following concept:
If terrorists/criminals could be caught by not having cryptography in our world, I would not blame data surveillance by governments and companies, nor the lack of cryptography in our communications/data storage.
I explained that this point of view is somehow twisted (as a knife can be used to do crimes, but its primary use is as a tool), but I didn't keep their attention.
Is there a best way to explain the value of cryptography for end-users in our modern world? (Snowden and Assange stories seems like fairy tales to them too).
Compendium: Some of the explanations/concepts that didn't work so far:
Would you let the government have a copy of your house key?
People tend to isolate data from house access, and they clearly would say "no, i do not want the government to have a copy of my house key and watch me doing private stuff. But if they are looking for a terrorist/criminal, it's fine to break the door". For them, it's okay since they don't break in your house while you are pooping. The existence of a "master key" on encryption world is fine to them. "My information is encrypted, but it could be turned into plain again in case of terrorism/crime".
Would you let others trace your life based on what you do online?
"But Google already does that based on emails and searches...". This mostly shocks me, because they are "with the flow" and they aren't bothered with data mining. Worse, people tend to trust way too much on Google.
What about the privacy of your communications? What if you are talking dirty things with your boy(girl)friend?.
"I don't talk about things that would harm others(criminally speaking) so, i don't mind on being MITM'ded.". Again, it's fine to them if a conversation about their sexual routine is recorded, if the intent is to investigate criminal activity on their city.
The Knife paradox.
You can see on their faces that this is a good one, but instead, they say that "knifes aren't as dangerous as secret information being traded between criminals so, it's okay that Knifes are misused by criminals sometimes".