> [...] my mother [...] came up with a code [...]
The problem with this is that your mother had a single secret, and had somehow arranged -- what they call "out of band" -- to transmit the code to the recipient. Once in place, it could be used.
It would be useful, in her case, only once.
http://en.wikipedia.org/wiki/One-time_pad
It would not be useful to transmit information about anything other than your planned emigration.
So: bravo to your mother; but: it doesn't scale.
Oh, and:
> You don't need encryption to keep secrets; you just need a
> willing and able partner.
Um, no ... you need -- and your mother relied upon -- encryption.
/jordan