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HOW TO PLAN A COUP D’ETAT COVERT MULTI-PARTY COMPUTATION YINMENG ZHANG ALADDIN REU 2005 LUIS VON...
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Transcript of HOW TO PLAN A COUP D’ETAT COVERT MULTI-PARTY COMPUTATION YINMENG ZHANG ALADDIN REU 2005 LUIS VON...
HOW TO PLAN A COUP D’ETAT
COVERT MULTI-PARTY COMPUTATION
YINMENG ZHANG
ALADDIN REU 2005
LUIS VON AHNMANUEL BLUM
TWO-PARTY COMPUTATION MULTI-PARTY COMPUTATIONCOVERT
ALLOWS TWO PARTIES WITH SECRET INPUTS X AND Y TO LEARN F(X,Y) BUT NOTHING ELSE
ALICE BOB
CHARLIE’S ANGEL
IDEAL MODEL
THERE ARE ONLY THREE ANGELS.NONE OF THEM KNOW ALICE.
OR BOB.
SECURE TWO PARTY COMPUTATION:YAO
F(X,Y) = 1 IF X>Y
0 OTHERWISE
$45 MILLION $32 MILLION
F(X,Y)=1
LET’S NOT GET MARRIED
JEN BEN
…
WHY WOULD WE WANT TO DO THAT?
OMGEVERYBODY!
BOB LIKES ME!
WHAT A LOSER!
BOBALICE
I ALICE
LET’S FIND OUT IF WE BOTH LIKE
EACH OTHER!
COVERT TWO PARTY COMPUTATION:VON AHN,HOPPER,LANGFORD
COVERT TWO-PARTY COMPUTATION
AFTER LEARNING F(X,Y), EACH PARTY CAN ONLY TELL WHETHER THE OTHER PARTICIPATED IF THEY CAN DISTINGUISH F(X,Y) FROM RANDOM BITS
EXTERNAL COVERTNESS
INTERNAL COVERTNESS
NO OUTSIDE OBSERVER CAN TELL IF THE TWO PARTIES ARE RUNNING A COMPUTATION OR JUST COMMUNICATING AS NORMAL
WHO KNOWS WHAT?
WE ASSUME THAT BOTH PARTIES KNOW THE FUNCTION THEY WISH TO EVALUATE
BOTH KNOW WHICH ROLE THEY ARE TO PLAY IN THE EVALUATION
BOTH KNOW WHEN TO START COMPUTING
ORDINARY COMMUNICATION
MESSAGES ARE DRAWN FROM A SET D
TIME PROCEEDS IN DISCRETE TIMESTEPS
EACH PARTY MAINTAINS A HISTORY h OF ALL DOCUMENTS THEY SENT AND RECEIVED
TO EACH PARTY P, WE ASSOCIATE A FAMILY OF PROBABILITY DISTRIBUTIONS ON D:
{BhP}
ORDINARY-LIKE COMMUNICATION
GIVEN ANY HISTORY h, P WANTS TO BE ABLE TO SAMPLE FROM THE CHANNEL Bh
P
CHANNEL ORACLE
THE WAR ON TERROR
I GUESS I CAN USE MY
BAZOOKA
HAVE YOU SEEN MY
AK-47?
YOU LEFT IT NEXT TO MY
GRENADES
THE AXIS OF EVIL SHALL PREVAIL!
MI-6 AGENT
CIA AGENT
HE WORKS FOR CIA
HE WORKS FOR MI-6
THE WAR ON TERROR
HE WORKS FOR CIA
HE WORKS FOR MI-6
THE UTTERANCES CONTAINED A
COVERT TWO-PARTY COMPUTATION
THE FUNCTION F VERIFIED THE CREDENTIALS
SINCE BOTH WERE VALID, IT OUTPUT 1K
X WAS A CREDENTIAL SIGNED
BY CIA AND Y WAS SIGNED BY MI-6
FOR ANY OTHER INPUTS, F OUTPUTS A RANDOM VALUE
SECURE MULTI PARTY COMPUTATION:GOLDREICH,MICALI,WIGDERSON
SECURE MULTI PARTY COMPUTATION:
YINMENG ZHANG???
WHAT I DID ON MY SUMMER VACATION[THE TEASER TRAILER]
COVERT MULTI-PARTY COMPUTATION
EVERYTHING IS HARDER WITH MORE PEOPLE
ALLOWS N PARTIES WITH SECRET INPUTS
X1…XN TO LEARN F(X1,…,XN) BUT NOTHING ELSE
COVERT MULTI-PARTY COMPUTATION:
THE ADVERSARY
WIMPY BUSYBODIES [SEMI-HONEST]
ALL’S FAIR IN LOVE AND CRYPTOGRAPHY [MALICIOUS]
WHAT THINGS ARE IMPOSSIBLE TO PROTECT AGAINST?
HOW MANY PEOPLE WERE COMPUTING, GOT BORED AND STOPPED[ABORT]?
HOW MANY PEOPLE ARE COMPUTING?
COVERT MULTI-PARTY COMPUTATION:WHO KNOWS WHAT?
WHO’S COMPUTING?