[Cryptography] Explaining PK to grandma

[James A. Donald]

If Grandma needs to understand public key cryptography to use your 
product, not only is grandma not going to use it, but cryptographers are 
not going to use it either.

The barrier is not the complexity of understanding.  The barrier is in 
the complexity of use.

If you hide the complexity of use, then grandma does not need to 
understand.  If you expose the complexity of use, it is too painful to 
use even if she does understand.