Secure Communication among members of the Order of the Phoenix

[vedaal_nistar]

No: HPFGUIDX 152451

Hello All,

am new here ;-)

My kids love discussing Harry Potter with me,
and we are all avid fans.

It just so happens, that among my other hobbies,
I am very interested in encryption/authentication/PGP/GnuPG
and have taught it to my kids.

So, I was intrigued and pleasantly surprised to find that JKR came 
up with a very clever mode of magical secure communication:
(JKR's official site: http://www.jkrowling.com/en/thankyou.cfm
faq section // about the books // p 1 of 4 )

JKR writes in the FAQ that Dumbledore invented a method of 
communication using Patronuses [? Patroni ? ;-) ]
and says that each Patronus is distinct to its Wizard/Witch,
so there is no possibility of forgery.

I don't remember where/which book this communication was used,
anyone know where ?


Also,
[1] does the Patronus deliver a message by speaking,(unlikely),
or by bringing a written message, as with Owl Post?

[2] can the Patronus be fooled into delivering the message
to a polyjuiced imposter?

{This would be a major weakness in cryptographic protocol. ;-) }
 
But could be made 'secure' by having the message be from Patronus 
to Patronus, and then having the receiving Patronus deliver the 
message to its Wizard/Witch.

Since the receiving Patronus cannot be forged, this would 
constitute quite a secure crypto-system {and one that is 
definitely much better than current Muggle systems. ;-) }

n.b.
JKR writes in her biographical notes,
that at one point she worked for Amnesty International,
so it is quite possible that she may have been familiar
with PGP crypto communication.

Thoughts/Ideas/Comments ?  :-)

Thanks,

All the Best,

vedaal